Tapping noise - Hot and Idle.

[JFP in PA]

Geflackt, you are not alone and have just detailed essentially the same list of items I checked/replaced in my garage a few years ago based on the exact same symptoms on my '07 Cayman S.  I can appreciate the effort and learning curve you speak of.  I also did one more major thing and pulled the trans to check the DMF for excessive wear (which can make a somewhat similar noise) and found it to be out of spec.  I replaced it to no avail.  If you ever find the exact smoking gun I would love to hear what it is, but here is what I do know:

 

It is certainly related to the oil system flow/pressure conditions as I tried multiple oil weights/brands and 3 different oil filters and they change the nature of the noise.  The biggest change came from removing the LN Engineering spin on oil filter adapter with Napa Gold filter (exact filter LN recommends) and putting the stock filter system back on.  This helped dramatically.  I had also replaced the Sport Chrono stopwatch with a high quality Spek oil pressure gauge and upon putting the stock filter back on picked up more oil pressure across the board.  Following that I cut open the Napa Gold filter and found the filter element to be crushed/collapsed, presumably from over pressurization due to no bypass valve for relief (stock valve is inside the plastic filter housing, so it gets eliminated by LN's kit).  It is not my intent to blame LN whatsoever, you make your choices and accept risks, but my oil pressure data and crushed filter experience convinced me that that adapter kit is not safe and it certainly exacerbated that noise.  The last "tweak" was changing to Castrol 5W-40 which is Porsche A40 (I tried multiple 0W-40, 5W-40, and 5W-50 weight oils, some Porsche A40, some not).  The heavier the oil weight the worse it was, which is contrary to the usual advice of a heavier oil to fix a noisy lifter at cold idle, but then again this noise is always hot idle and never cold idle.

 

I'm not claiming its the best oil ever or that M1 is junk but using that oil with the stock filter essentially solved the problem.  After many thousand miles on rare occasion I hear a tap or two but nothing like it was.  Good luck, I know I pulled my hair out trying to solve it.

 

I have to say that  I am both amazed, and somewhat concerned by several of your comments for a variety of reasons.  We have many, many customers running the LN spin on set up, which I also use on my personal cars.  As we always cut open every oil filter on every car we service, I have to say that we have never seen the filter element in the NAPA filters collapsed or otherwise damaged or distorted in any of the literally hundreds of oil filters we regularly see.  As several of the cars we service utilize aftermarket oil pressure gauges, we have also not observed any significant differences in oil pressure when switching from one filter system to the other.  And as the NAPA filter internal structure is completely supported by metal rather than the entirely treated paper construction of the OEM style filter, I would expect that the OEM filter would suffer significantly more damage if used in the same oiling system.  Do you by chance save any photos of the spin on filter which failed?

 

I am also intrigued by you oil comments for similar reasons.  We have seen many customer cars with complaints of cold start noise, particularly when running the 0W-40 M1 product, that were either significantly improved or completely eliminated by moving to higher weight oils with superior film strengths compared to the M1 product.  On the basis of my shop's observations over many cars, I have obviously having some difficulties understanding what you are seeing.

[Tash]

Mine seems to have settled today, just drove it around in normal driving and took it on a steady 3000rpm run for 10mile, seems much better when warm so starting to think it is a lifter not holding, would say it's definately on bank 1-3 (drivers side in UK)

[vizor]

JFP, I certainly understand where you are coming from.  To be clear once again I harbor no ill will towards LN Engineering and Charles was kind enough to correspond with me when I first began chasing this tapping noise many years ago.  Many months later when this came to light and seemingly "fixed" the issue I shared my findings with Charles but never recieved a response.  That doesn't prove anything, but its not fair to share on the internet without giving the creator a chance to respond, etc.  I documented all my work on another forum chasing the problem from the beginning that eventually lead to this.  Further, I have a masters degree in mechanical engineering and worked professionally designing fluid systems (fuel, brakes, coolant, and oiling) for multiple professional race teams over the years, so I have a strong academic and working knowledge of these systems.  I only now brought it up in hopes of helping Geflackt because I worked at solving it for far too long, and Porsche dealerships as well as Porsche specialist indy shops that looked at my car all scratch their head.  I feel fairly confident its a little slop in the system that manifests only when the exact mechancial conditions are right, like the "right" (=wrong) tolerance stack up, no engine load, and too little oil flow, etc.  Given that modern engines use the oil just as much like hydraulic oil to run various systems as much as for traditional lubrication they have become that much more sensitive to exact oil flow conditions. 

 

To the point, here is an exploded view of an intake lifter for our cars that I made during my efforts.  You can see there are a lot of small moving parts, one is the pin that moves laterally by way of oil pressure to lock the high lift and low lift portions together.  That happens at somewhere around 3200 RPM when VC+ kicks in, its not hard to imagine the hard life this component lives and how if one were a little less than perfect you could have some issues.  Based on having rebuilt the heads on a few other 996/997 vehicles I have seen these lifters fall apart in my hand as they were removed and yet the engine still ran OK if not a little loud and rough.  JFP I'm sure you've seen this too.

 

 

At the time I only found one other gentlemen in TX experiencing the same and he said:

 

"I first noticed the noise after changing the oil, so I assumed that it had something to do with the Pennzoil Ultra 5W-40 Euro that I had just put in, or the filter and adapter that I got from LN Engineering. As you noted from the video, the sound was terrible at first; I thought the engine was about to let go!  I brought it to my local independent Porsche shop and they replaced the filter with a stock Porsche OEM unit and replaced the 5W-40 with 0W-30 thinking that one or more of the lifters was sticking and the thinner oil would help unstick it. I also added some MMO to assist in that process. The shop owner told me to drive it hard and I did (while this made me nervous with 0W-30, a UOA showed no atypical wear for the 1000 miles that the thinner oil was in).  After some time the noise got quieter. I haven't driven the car in a while, but I think the noise is gone or quiet enough that I can't hear it."

 

So, to isolate things better I only changed back to the factory oil filter and did nothing else except a little make up oil to replace what was lost in the oil filter change. The noise immediately got better.  I’m sure there must be tons of these adapters out there and if this is not common there must be extenuating circumstances required for it to manifest, however I’m still not sure what that is exactly.

Since my oil pressure gauge was installed after the spin on adapter was present, I had no reference oil pressure behavior with the factory system, but once I put the factory oil filter back on I immediately read about 5 psi higher cold start oil pressure at idle and even more pressure difference if you blip the throttle when it’s cold, easily passing 90 psi and still climbing. I don’t know how high it would go as I am extremely gentle on driving the car until its warm, in fact that’s a big reason I installed the gauge so I would know when the oil was fully up to temp (by way of a stabilized hot idle pressure) before driving it hard.  At cold start up the spin on oil adapter only allowed the oil pressure to reach 80 psi and wouldn't pass 85 psi if you give it throttle (with 5W-XX oil). While I'm not super concerned about the cold pressure behavior, I still saw an increase at hot idle with the factory filter, which did concern me since I’m sure the filter by-pass valve and the oil pump PRV are not open. 

 

To respond to your other question/concern I guess the factory paper filter element (which agreed is definately not as substantially supported as the Napa Gold) does not experience collapse because:

 

1) there is a by-pass valve present precisely to prevent this. 

2) it may have more surface area than the Napa Gold 1042 = potentially less restriction for the same oil flow

3) it may provide less filtration through a more open free flowing element = potentially less restrictive for the same oil flow

 

So with the LN adapter and spin on filter given the right combination of oil weight, cold temps, and enough revs you may produce enough pressure differential across the filter element to damage it since there are no provisions for relief.

From all this it was clear to me the spin on LN recommended NAPA Gold 1042 was more restrictive. So as mentioned I cut open the spin on filter I had just removed and found signs of collapse.  I imagine this occured when the oil was cold, but I can’t be sure as it never got that cold where I was living at the time, typical start up temps for me during the winter were around 45-50 F.  Its been a few years, this is the only picture I could find.

 

[RFM]

Interesting, instructive statement and pictures on oil choise and modified lubrication system. However it looks peculiar that in this case, the black casing/shell of the oil filter is not a little distended caused by the high oil pressure.

[JFP in PA]

JFP, I certainly understand where you are coming from.  To be clear once again I harbor no ill will towards LN Engineering and Charles was kind enough to correspond with me when I first began chasing this tapping noise many years ago.  Many months later when this came to light and seemingly "fixed" the issue I shared my findings with Charles but never recieved a response.  That doesn't prove anything, but its not fair to share on the internet without giving the creator a chance to respond, etc.  I documented all my work on another forum chasing the problem from the beginning that eventually lead to this.  Further, I have a masters degree in mechanical engineering and worked professionally designing fluid systems (fuel, brakes, coolant, and oiling) for multiple professional race teams over the years, so I have a strong academic and working knowledge of these systems.  I only now brought it up in hopes of helping Geflackt because I worked at solving it for far too long, and Porsche dealerships as well as Porsche specialist indy shops that looked at my car all scratch their head.  I feel fairly confident its a little slop in the system that manifests only when the exact mechancial conditions are right, like the "right" (=wrong) tolerance stack up, no engine load, and too little oil flow, etc.  Given that modern engines use the oil just as much like hydraulic oil to run various systems as much as for traditional lubrication they have become that much more sensitive to exact oil flow conditions. 

 

To the point, here is an exploded view of an intake lifter for our cars that I made during my efforts.  You can see there are a lot of small moving parts, one is the pin that moves laterally by way of oil pressure to lock the high lift and low lift portions together.  That happens at somewhere around 3200 RPM when VC+ kicks in, its not hard to imagine the hard life this component lives and how if one were a little less than perfect you could have some issues.  Based on having rebuilt the heads on a few other 996/997 vehicles I have seen these lifters fall apart in my hand as they were removed and yet the engine still ran OK if not a little loud and rough.  JFP I'm sure you've seen this too.

 

exploded view lifter.jpg

 

At the time I only found one other gentlemen in TX experiencing the same and he said:

 

"I first noticed the noise after changing the oil, so I assumed that it had something to do with the Pennzoil Ultra 5W-40 Euro that I had just put in, or the filter and adapter that I got from LN Engineering. As you noted from the video, the sound was terrible at first; I thought the engine was about to let go!  I brought it to my local independent Porsche shop and they replaced the filter with a stock Porsche OEM unit and replaced the 5W-40 with 0W-30 thinking that one or more of the lifters was sticking and the thinner oil would help unstick it. I also added some MMO to assist in that process. The shop owner told me to drive it hard and I did (while this made me nervous with 0W-30, a UOA showed no atypical wear for the 1000 miles that the thinner oil was in).  After some time the noise got quieter. I haven't driven the car in a while, but I think the noise is gone or quiet enough that I can't hear it."

 

So, to isolate things better I only changed back to the factory oil filter and did nothing else except a little make up oil to replace what was lost in the oil filter change. The noise immediately got better.  I’m sure there must be tons of these adapters out there and if this is not common there must be extenuating circumstances required for it to manifest, however I’m still not sure what that is exactly.

Since my oil pressure gauge was installed after the spin on adapter was present, I had no reference oil pressure behavior with the factory system, but once I put the factory oil filter back on I immediately read about 5 psi higher cold start oil pressure at idle and even more pressure difference if you blip the throttle when it’s cold, easily passing 90 psi and still climbing. I don’t know how high it would go as I am extremely gentle on driving the car until its warm, in fact that’s a big reason I installed the gauge so I would know when the oil was fully up to temp (by way of a stabilized hot idle pressure) before driving it hard.  At cold start up the spin on oil adapter only allowed the oil pressure to reach 80 psi and wouldn't pass 85 psi if you give it throttle (with 5W-XX oil). While I'm not super concerned about the cold pressure behavior, I still saw an increase at hot idle with the factory filter, which did concern me since I’m sure the filter by-pass valve and the oil pump PRV are not open. 

 

To respond to your other question/concern I guess the factory paper filter element (which agreed is definately not as substantially supported as the Napa Gold) does not experience collapse because:

 

1) there is a by-pass valve present precisely to prevent this. 

2) it may have more surface area than the Napa Gold 1042 = potentially less restriction for the same oil flow

3) it may provide less filtration through a more open free flowing element = potentially less restrictive for the same oil flow

 

So with the LN adapter and spin on filter given the right combination of oil weight, cold temps, and enough revs you may produce enough pressure differential across the filter element to damage it since there are no provisions for relief.

From all this it was clear to me the spin on LN recommended NAPA Gold 1042 was more restrictive. So as mentioned I cut open the spin on filter I had just removed and found signs of collapse.  I imagine this occured when the oil was cold, but I can’t be sure as it never got that cold where I was living at the time, typical start up temps for me during the winter were around 45-50 F.  Its been a few years, this is the only picture I could find.

 

filter collapse.jpg

 

I am not at all surprised at your observed difference in cold start oil pressure with the OEM style filter vs. the full flow NAPA unit.  That is the bypass valve in operation, allowing unfiltered oil to go around the filter media.  Over the years, I have lost count of the number of OEM cartridge units we have observed with the rather flimsy bypass valve in the bottom of the housing permanently jammed open, meaning that most (if not all) of the oil is not being filtered, but generating slightly higher observed oil pressure because it is not being filtered, as there is no pressure loss across the filter media.

 

As for the 1042 filter photo, I would have to agree with RFM, the internal metal support structure on the 1042 is substantially thicker than the outer shell housing; so if enough excessive pressure was present to deform the internals, I would expect the thinner outer housing to also be "ballooned" from it as well:

 

 

I realize that does not explain how the obvious mechanical distortion occurred, but I do not believe it is from excessive oil pressure, which in any case would be limited by the relief valve on the oil pump.

 

The NAPA 1042 is slightly more restrictive compared to the OEM style filter as the media has about a 30% finer pore diameter and is a "full flow" design (read no bypass) so that 100% of the oil is filtered 100% of the time in order to improve the effectiveness of the unit in cleaning the oil.  The difference in oil pressure you observed is not unusual (85 PSIG vs. 90 with throttle application when cold), but at least in my opinion is not enough to explain the difference in the engine sounds, particularly as most engine noise complaints we see are at warm idle, when both filters are similar in oil pressure.

 

As for you lifter observations, yes, we have seen very much the same thing, but with one additional observation:  Both the VarioCam and VarioCam + system lifters are an oil passage "dead end" design (read there is no oil flow through the lifter to clean it, it enters the lifter and simply stops, leaving behind very old and dirty oil, varnish and any debris circulating within the oil system).  This has always been considered a limitation of this design.  It is not unusual to remove the lifters from an otherwise internally clean engine that when placed in a bath of clean thin oil and then pumped by hand immediately puke out some very black and foul smelling ugly crud.  This burnt and fouled oil is the reason that these lifters develop problems, including internal wear that allows them to simply fall apart when removed, much like the burnt oil often found trapped in the IMS bearings when the rear seal is removed.  Considering the dead end design, it is not at all surprising that some people have found that running thinner oil helps with the noise, but unfortunately does not offer the high temperature/ high shear protection of a higher weight oil.  It also explains why some engines that are quiet at cold start, when the oil is thin, become more noisy as the oil thickens with temperature.

[vizor]

To the OP, apologies if this turned into a thread hijack.  I just wanted to give a tip to make the noise go away based on my and another gentlemen's experience.  Especially since you've covered so many items already, I would suggest experimenting with oil filter and oil brand/weight before anything else.

 

JFP,

This is good conversation, perhaps we should take this to another thread?

I am not at all surprised at your observed difference in cold start oil pressure with the OEM style filter vs. the full flow NAPA unit.  That is the bypass valve in operation, allowing unfiltered oil to go around the filter media.  Over the years, I have lost count of the number of OEM cartridge units we have observed with the rather flimsy bypass valve in the bottom of the housing permanently jammed open, meaning that most (if not all) of the oil is not being filtered, but generating slightly higher observed oil pressure because it is not being filtered, so there is no pressure loss across the filter media.

I suspect you're generally correct, and like everyone else I would prefer 100% filtration, hence the LN adapter and spin on filter.  However I don't know for sure when the factory filter bypass valve is in operation.  If you have Porsche specs that detail what pressure differential across the filter media (the only pressure this valve references) causes the bypass valve to open I would love to know.  I think a typical number in the industry is around 10-12 psi.  Then we need to instrument both the high and low pressure side of the oil filter media to find out under what operating conditions this pressure differential really exists to open the bypass valve.

 

 

As for the 1042 filter photo, I would have to agree with RFM, the internal metal support structure on the 1042 is substantially thicker than the outer shell housing; so if enough excessive pressure was present to deform the internals, I would expect the thinner outer housing to also be "ballooned" from it as well:

I realize that does not explain how the obvious mechanical distortion occurred, but I do not believe it is from excessive oil pressure.

Nice one!  What filter is that and what total system pressure caused that level of damage to the casing?  Does that filter have the bypass valve built into it or is it in the block of the car engine like many cars?

 

Second, the filter casing sees the maximum total pressure in the system whereas if the filter bypass valve is sized adequately it can keep the pressure differential across the element low enough to prevent damage to it (once again that's pretty much its job).  This is why you can split a filter canister open or blow out its seals and the element may still look OK.  The critical difference between the above and our situation is the Napa Gold 1042 has no internal bypass valve, and our engine block does not have it either (because its built into the bottom of the factory reuasble plastic filter housing) so by using the spin on adapter you have changed the base system.  So I believe its possible in this condition to produce enough oil flow (presumably at cold oil temps) to create a pressure differential across the filter to hurt it all while the total system pressure remains low enough that the outer casing does not deform or fail.  I don't have the data to prove it explicity, but I believe its easily plausible.

 

 

The NAPA 1042 is slightly more restrictive compared to the OEM style filter as the media has about a 30% finer pore diameter and is a "full flow" design (read no bypass) so that 100% of the oil is filtered 100% of the time in order to improve the effectiveness of the unit in cleaning the oil.

True, however I bet all the applications that call for this filter from the book have a filter bypass valve built into the engine block. I can't imagine any filter media designed to withstand a pressure differential across it equal to the total system pressure.

 

 

The difference in oil pressure you observed is not unusual (85 PSIG vs. 90 with throttle application when cold), but at least in my opinion is not enough to explain the difference in the engine sounds, particularly as most engine noise complaints we see are at warm idle, when both filters are similar in oil pressure.

I also experienced slightly higher oil pressure at warm idle with the stock oil filter.  This of course is not a real surprise if the Napa 1042 is more restrictive...it will be at all conditions to varying degrees.  And it was with the exact same oil since I kept the oil and only changed the filter.  I also have Durametric so I know the oil temps were also equal when I referenced the pressure, which is critical for an accurate comparison.

 

As for you lifter observations, yes, we have seen very much the same thing, but with one additional observation:  Both the VarioCam and VarioCam + system lifters are an oil passage "dead end" design (read there is no oil flow through the lifter to clean it, it enters the lifter and simply stops, leaving behind very old and dirty oil, varnish and any debris circulating within the oil system).  This has always been considered a limitation of this design.  It is not unusual to remove the lifters from an otherwise internally clean engine that when placed in a bath of clean thin oil and then pumped by hand immediately puke out some very black and foul smelling ugly crud.  This burnt and fouled oil is the reason that these lifters develop problems, including internal wear that allows them to simply fall apart when removed, much like the burnt oil often found trapped in the IMS bearings when the rear seal is removed.  Considering the dead end design, it is not at all surprising that some people have found that running thinner oil helps with the noise, but unfortunately does not offer the high temperature/ high shear protection of a higher weight oil. 

 

 

To be clear I am not advocating running the thinnest oil you can stand and still sleep at night, you can take that too far and do some real damage.  From my experience the thicker HOT weight was the wrong direction, ie 0W-40 or 5W-40 was better than 5W-50.  Agreed a lower HTHS is not preferable on one hand, but it does support a slightly lower viscosity was still directionally correct to stop the noise, and if you're one of the unfortunate few with this affliction, that aweful noise does not seem so preferable either!  :cursing:   I am certainly not here to sell Castrol or a particular oil weight, just report what worked for me and what data and experience I have to support it...if one finds something that works better for them, use it!

 

Agreed the lifters are a dead end design, but they still require a non-zero flow rate to operate properly.  They all experience some small amount of leak down in operation and when sitting with the engine off.  The switchable lifters on the intake side even more so because the lock pin is dependent on oil to actuate.

 

It also explains why some engines that are quiet at cold start, when the oil is thin, become more noisy as the oil thickens with temperature.

This is not true and a common misconception about multi weight oils.  In the case of a 5W-40, the oil behaves like the viscosity a SAE 5 weight oil would at the cold test temperature, but at the hot test temperature it behaves like the viscosity of a SAE 40 weight oil.  This does not mean the actual viscosity when cold is thinner than when hot.  If this were true you would see your idle oil pressure rise as the engine warms.

 

When the oil is cold you need a lightweight oil so it remains thin enough to flow adequately, but if you were to use that same oil when it gets really hot it would become "thinner than water."  But of course if you have a 40 weight oil to solve the hot running condition its so thick when cold it just won't flow adequately.  (This was the case way back in the day and you might have had to change your oil on a seasonal basis to compensate.)  Multi weight oils transition their behavior from that of a thinner (ie SAE 5) oil to a thicker (ie SAE 40) oil as they warm BUT their actual viscosity trends thinner and thinner with increasing temperature.

[JFP in PA]

To the OP, apologies if this turned into a thread hijack.  I just wanted to give a tip to make the noise go away based on my and another gentlemen's experience.  Especially since you've covered so many items already, I would suggest experimenting with oil filter and oil brand/weight before anything else.

 

JFP,

This is good conversation, perhaps we should take this to another thread?

I am not at all surprised at your observed difference in cold start oil pressure with the OEM style filter vs. the full flow NAPA unit.  That is the bypass valve in operation, allowing unfiltered oil to go around the filter media.  Over the years, I have lost count of the number of OEM cartridge units we have observed with the rather flimsy bypass valve in the bottom of the housing permanently jammed open, meaning that most (if not all) of the oil is not being filtered, but generating slightly higher observed oil pressure because it is not being filtered, so there is no pressure loss across the filter media.

I suspect you're generally correct, and like everyone else I would prefer 100% filtration, hence the LN adapter and spin on filter.  However I don't know for sure when the factory filter bypass valve is in operation.  If you have Porsche specs that detail what pressure differential across the filter media (the only pressure this valve references) causes the bypass valve to open I would love to know.  I think a typical number in the industry is around 10-12 psi.  Then we need to instrument both the high and low pressure side of the oil filter media to find out under what operating conditions this pressure differential really exists to open the bypass valve.

 

 

As for the 1042 filter photo, I would have to agree with RFM, the internal metal support structure on the 1042 is substantially thicker than the outer shell housing; so if enough excessive pressure was present to deform the internals, I would expect the thinner outer housing to also be "ballooned" from it as well:

I realize that does not explain how the obvious mechanical distortion occurred, but I do not believe it is from excessive oil pressure.

Nice one!  What filter is that and what total system pressure caused that level of damage to the casing?  Does that filter have the bypass valve built into it or is it in the block of the car engine like many cars?

 

Second, the filter casing sees the maximum total pressure in the system whereas if the filter bypass valve is sized adequately it can keep the pressure differential across the element low enough to prevent damage to it (once again that's pretty much its job).  This is why you can split a filter canister open or blow out its seals and the element may still look OK.  The critical difference between the above and our situation is the Napa Gold 1042 has no internal bypass valve, and our engine block does not have it either (because its built into the bottom of the factory reuasble plastic filter housing) so by using the spin on adapter you have changed the base system.  So I believe its possible in this condition to produce enough oil flow (presumably at cold oil temps) to create a pressure differential across the filter to hurt it all while the total system pressure remains low enough that the outer casing does not deform or fail.  I don't have the data to prove it explicity, but I believe its easily plausible.

 

 

The NAPA 1042 is slightly more restrictive compared to the OEM style filter as the media has about a 30% finer pore diameter and is a "full flow" design (read no bypass) so that 100% of the oil is filtered 100% of the time in order to improve the effectiveness of the unit in cleaning the oil.

True, however I bet all the applications that call for this filter from the book have a filter bypass valve built into the engine block. I can't imagine any filter media designed to withstand a pressure differential across it equal to the total system pressure.

 

 

The difference in oil pressure you observed is not unusual (85 PSIG vs. 90 with throttle application when cold), but at least in my opinion is not enough to explain the difference in the engine sounds, particularly as most engine noise complaints we see are at warm idle, when both filters are similar in oil pressure.

I also experienced slightly higher oil pressure at warm idle with the stock oil filter.  This of course is not a real surprise if the Napa 1042 is more restrictive...it will be at all conditions to varying degrees.  And it was with the exact same oil since I kept the oil and only changed the filter.  I also have Durametric so I know the oil temps were also equal when I referenced the pressure, which is critical for an accurate comparison.

 

As for you lifter observations, yes, we have seen very much the same thing, but with one additional observation:  Both the VarioCam and VarioCam + system lifters are an oil passage "dead end" design (read there is no oil flow through the lifter to clean it, it enters the lifter and simply stops, leaving behind very old and dirty oil, varnish and any debris circulating within the oil system).  This has always been considered a limitation of this design.  It is not unusual to remove the lifters from an otherwise internally clean engine that when placed in a bath of clean thin oil and then pumped by hand immediately puke out some very black and foul smelling ugly crud.  This burnt and fouled oil is the reason that these lifters develop problems, including internal wear that allows them to simply fall apart when removed, much like the burnt oil often found trapped in the IMS bearings when the rear seal is removed.  Considering the dead end design, it is not at all surprising that some people have found that running thinner oil helps with the noise, but unfortunately does not offer the high temperature/ high shear protection of a higher weight oil. 

 

 

To be clear I am not advocating running the thinnest oil you can stand and still sleep at night, you can take that too far and do some real damage.  From my experience the thicker HOT weight was the wrong direction, ie 0W-40 or 5W-40 was better than 5W-50.  Agreed a lower HTHS is not preferable on one hand, but it does support a slightly lower viscosity was still directionally correct to stop the noise, and if you're one of the unfortunate few with this affliction, that aweful noise does not seem so preferable either!  :cursing:   I am certainly not here to sell Castrol or a particular oil weight, just report what worked for me and what data and experience I have to support it...if one finds something that works better for them, use it!

 

Agreed the lifters are a dead end design, but they still require a non-zero flow rate to operate properly.  They all experience some small amount of leak down in operation and when sitting with the engine off.  The switchable lifters on the intake side even more so because the lock pin is dependent on oil to actuate.

 

It also explains why some engines that are quiet at cold start, when the oil is thin, become more noisy as the oil thickens with temperature.

This is not true and a common misconception about multi weight oils.  In the case of a 5W-40, the oil behaves like the viscosity a SAE 5 weight oil would at the cold test temperature, but at the hot test temperature it behaves like the viscosity of a SAE 40 weight oil.  This does not mean the actual viscosity when cold is thinner than when hot.  If this were true you would see your idle oil pressure rise as the engine warms.

 

When the oil is cold you need a lightweight oil so it remains thin enough to flow adequately, but if you were to use that same oil when it gets really hot it would become "thinner than water."  But of course if you have a 40 weight oil to solve the hot running condition its so thick when cold it just won't flow adequately.  (This was the case way back in the day and you might have had to change your oil on a seasonal basis to compensate.)  Multi weight oils transition their behavior from that of a thinner (ie SAE 5) oil to a thicker (ie SAE 40) oil as they warm BUT their actual viscosity trends thinner and thinner with increasing temperature.

 

Let's try and take this in order:  The bypass valve is not rated to my knowledge.  What I am sure of is that they fail over time, either opening sooner than they should or sticking completely open, either of which results in unfiltered oil getting into all parts of the engine, including the dead end lifters.

 

The ballooned filter is a similar NAPA Gold unit that was on an LS engine in a Corvette.  The final pressure was unknown as it destroyed the pressure gauge as well as the filter and several other seals in the engine.  But interestingly, the filter's internals were fine, just the shell was ballooned.  As to your question about bypass mounted elsewhere, total non bypass engines are fairly common these days in several domestic and most Asian vehicles.  With modern synthetics, the severe high cold oil pressures are pretty much a thing of the past, and the OEM's are quick to remove anything the engine does not need in order to save money, even a fifty cent plastic bypass valve.

 

Lighter weight oils:  Better cold flowing oils are able to get into the fouled lifters more easily than heavy weigh oils, giving the impression that thin oils are the answer to lifter noise.  Problem is that the lighter oils do not pack the HTHS protection of the heavier oils, which puts other component's at risk.  There is not such thing as a free lunch when it comes to oils, everything is a compromise.

 

When I refer to cold start viscosity, I am thinking of the Kinematic standard in wide use, which is a measure of the fluids resistance to flow, as opposed to dynamic viscosity which is the fluid's resistance to a torque  force exerted upon it.  As most motor oils viscosities are measure using the capillary tube viscometer, they are kinematic in nature.  This procedure is described in ASTM D445 and ISO 3104.  So when I refer to "thin", I am thinking of its kinematic, or flow characteristics.

[vizor]

But interestingly, the filter's internals were fine, just the shell was ballooned.

I realize this may not seem so, but this supports what I wrote above as to how one can easily destroy the casing without hurting the filter media when a oil filter bypass valve is present, which to my knowledge the LS engines have in their block.  It does not mean the opposite can't be true when a oil filter bypass valve is not present.

 

 

total non bypass engines are fairly common these days in several domestic and most Asian vehicles.  With modern synthetics, the severe high cold oil pressures are pretty much a thing of the past, and the OEM's are quick to remove anything the engine does not need in order to save money, even a fifty cent plastic bypass valve.

 

Are you talking about the oil filter bypass valve or the oil pump pressure regulating valve (PRV, sometimes called bypass too)?  I am aware that many cars (including the newer Porsches) have an ECU controlled variable volume oil pump which disconnects the long standing history of oil pump output being tied directly to engine RPM.  In these cars, you can rev it all you want hot or cold but the ECU is in control of the resulting oil flow instead of a passive PRV.  If this level of control can adequately protect the filter media and eliminate the oil filter bypass valve, then cool!  One less cost engineering rant I have to sit through everyday.

 

If you know of a traditional oil pump with a passive PRV that does not have an oil filter bypass valve I would like to look at it and see what accomodations they made, seriously.

 

 

Lighter weight oils:  Better cold flowing oils are able to get into the fouled lifters more easily than heavy weigh oils, giving the impression that thin oils are the answer to lifter noise.  Problem is that the lighter oils do not pack the HTHS protection of the heavier oils, which puts other component's at risk.  There is not such thing as a free lunch when it comes to oils, everything is a compromise.

Agreed, no arguement about HTHS, that's why I was happy that what seems to be the optimum set up to alleviate the noise (which may or may not be a lifter, I still don't know for sure what it is... for a while there I was certain it was timing chain slap) was an oil that is Porsche A40 and therefore meets their HTHS requirements.  And FWIW, its also the oil that Charles and/or Jake were recommending at one point I think, maybe they still do if you're not buying their oil.

 

 

When I refer to cold start viscosity, I am thinking of the Kinematic standard in wide use, which is a measure of the fluids resistance to flow, as opposed to dynamic viscosity which is the fluid's resistance to a torque  force exerted upon it.  As most motor oils viscosities are measure using the capillary tube viscometer, they are kinematic in nature.  This procedure is described in ASTM D445 and ISO 3104.  So when I refer to "thin", I am thinking of its kinematic, or flow characteristics.

To be honest I think that is talking around the subject without coming clean on an error.  The kinematic viscosity is what's published on all the oil spec sheets per the ASTM D445 you reference.  So read it, it clearly shows the kin viscosity is higher (= "thicker" = more resitant to flow = produces more oil pressure at a given oil temp and flowrate) at the cold 40C test temp than it does at the hot 100C test temp.  Look at the M1 0W-40 PDS sheet.  The kin vis drops over 5.5 times for only a 60C temp rise.

 

Mobil 1 0W-40

Viscosity, cSt (ASTM D445)

75 cSt @ 40C

13.5 cSt @ 100C

 

All that aside, for anyone interested the HTHS is more analogous to the real operational viscosity in the engine than the kinematic viscosity, because the HTHS test includes pressure on the fluid sample which effects the apparent viscosity.  So even if two oils have the same 100C kin vis your oil pressure gauge will read higher with the oil that has the higher HTHS.  Is this why Castrol 5W-40 seemed to be slightly better than M1 0W-40 at mitigating the noise?? I don't know but from the PDS I can find online it does have a slightly lower HTHS than M1 0W-40, so maybe it tickles all the nooks and cranies just right.

[JFP in PA]

I was referring to the oil filter bypass, not the pump pressure regulation valve, which is a different item entirely.

 

I read in the trade press that some LS engines use a block off plate in place of the block mounted filter circuit bypass unit, but off hand I do not remember which ones.  Likewise, there are a couple Toyota and Nissan engines that use full flow oil filters and supposedly do not have any other filter circuit bypass; which may be related to ultra light factory oil spec of 0W-20 full synthetics for these engines.  I think this configuration is used in their hybrid models.

 

Porsche uses both a variable oil pump system  and a thermal control network on the 9A1 engines which alter both the oil flow and engine coolant temperatures based upon throttle demand.  A similar technology has been around for along time in aftermarket dry sump systems which show higher oil pressures at low RPM's, which seems counter intuitive to the way oiling systems normally function.

[Geflackt]

Slight Update:  No definitive solution/cure yet on this noise.  I have swapped the cam solenoids and screen/check valves side-to-side.  Plus I have driven approx 300 miles in the last week or so.  

The noise is not completely gone, but is either quieter or non-existent.  There are times I've pulled into the garage and idled the car for over a minute with no sound.  Occasionally after a drive, the tapping sound is present, but not as loud, sometimes fading out.  With the solenoid swap, I can't quite tell if the tap has moved from Left to Right - I've not put the car back on the lift but on the ground it's still sort of left-sided.

 

The car is running strong, fuel mileage is good, no oil consumption that's noticeable yet - and the car seems happy to be driven.  It's been fun exploring the upper RPM range, too!

[Tash]

Geflackt, what do you think sorted it in end? The cam solenoids

Edited April 14, 2015 by Tash

[Geflackt]

Geflackt, what do you think sorted it in end? The cam solenoids

I don't believe swapping the solenoids did it.  The noise also isn't completely gone, but it does happen less often now that I'm out driving the car.  Again, when I got the car last year it had barely been driven, then I went at solving the noise without really driving the car.

I swapped the solenoids to see if the noise would follow - such as if the solenoid spring was weak or the filter/check-valve under the solenoid was restricting flow.  Looking for a possibility of the intake came sprocket to be "clacking" due to lack of pressure or flow.

[Tash]

Thinking of changing to Shell Helix Ultra 0w40 oil, recently had change to Petronas 5w40 which did make a difference.

Car doesn't get out much, sits all week and on weekend does minimal miles, the noise does quieten as the temperature rises but never fully goes, from outside an audible tick can be heard on both sides but would say it is louder on bank 1-3.

[Tash]

Bought the 0w40 shell helix ultra to give this ago, will post how I get on.

[Pete54]

I bought a 1999 Boxster with 17,000 miles on it several years back. The engine sounded perfect until the first oil change. After that I started getting a tappet noise which DOVE ME CRAZY! The local Porsche dealer did the oil change.  I brought it to another garage that specializes in Porsches and they ran lifter cleaner through it which did not help.

 

The problem was this: when the engine was cold it was quiet but after I drive it for a while I could hear tappet noise with the top up, or when I was at an idle with the top down. When I revved the car the noise would go away for a short while.  Finally, after this problem drove me crazy for three years I added  Lucas synthetic oil stabilizer. If you are old enough to remember STP additive it appears similar to that, basically a really thick additive. I started the car after the oil change when Lucas was added and the lifter noise was gone. I stored the car last year and when I picked it up this year and since then, no lifter noise. Okay, maybe a couple of tappets are noisy for a second after starting but then quiet.

 

I use 0-40 Mobile One synthetic. My guess it an increase in viscosity is allowing the lifters to operate like they are supposed to. I would guess that you can use any additive that increases viscosity as long as it is a synthetic additive. 

 

Looking back it makes sense. The old owner probably put an additive in the oil to quiet the lifters. When I had the oil changed it had stock oil and the lifters were noisy. When the car was warm the oil wasn't thick enough to make the lifters operate properly so they were noisy.. Also when I revved the engine the oil pressure would increase quieting the lifters.

 

I would guess that a thicker oil may make it harder to keep oil in the IMS bearing? So use any oil additive at your own risk.