Reliability of 996 Engines

[jthailer]

Johhnyreb,

Take your car to a PCA track event. You will have a whole new appreciation for what your car car do. It is not all about HP. HP is great in a straight line after that it is all about handling and braking ability.

[eso1968]

While I took my car to my mechanic for brake replacement, he had the car jacked up and noticed some oil leaking issues. I therefore asked him to look further by removing the plastic trims. From there onwards, we have noticed that some oil leaks problems.... only solution is to get it fix before it get worse.

The only solution is to have thew whole engine and gearbox removed (please see photo). After removal, we have noticed that the engine which has done 55000km of my car has been attached to the car since it came from the factory, i.e. has never been removed. Therefore, it is about time before something horrible happen.

Now, all these seals have been ordered and hopefully by the time it has been fixed, I will have a reliable car to drive for at least a few years.

[jroberts38]

I thought I would throw in my two cents on this issue. I recently had an IMS bearing failure while on a trip. Even though I shut the engine down as soon as I heard an unfamiliar noise, the bearing still damaged the snap ring ridge on the intermediate shaft. It looks like it will need a complete rebuild. I can't believe Porsche would design a sealed bearing for this application, when there is plenty of oil to be had in this location of the engine! I am considering Motormeister out of California. Are there any other quality rebuilders out there for this engine? I have a 2003 model with 60k on the clock.

[Basalt 911]

I thought I would throw in my two cents on this issue. I recently had an IMS bearing failure while on a trip. Even though I shut the engine down as soon as I heard an unfamiliar noise, the bearing still damaged the snap ring ridge on the intermediate shaft. It looks like it will need a complete rebuild. I can't believe Porsche would design a sealed bearing for this application, when there is plenty of oil to be had in this location of the engine! I am considering Motormeister out of California. Are there any other quality rebuilders out there for this engine? I have a 2003 model with 60k on the clock.

This reply might be too late too help, but the shop below has been rebuilding 996 motors well before most independent shops even knew how.

http://autostrassecorp.com/

[babylonboots]

Yes, I am working on 101 for the 996, it should be out in 2011!

Thx, Wayne

Keep us posted! Can't learn enough about these great automobiles.

Edited January 16, 2011 by babylonboots

[mountainman]

I have been a porsche owner since I bought a 356SC in 1964. Always very pleased with Porsche until recently when the intermediate shaft failed on my 46K mile 2002 C4. Checked with every Porsche dealer within 200 miles ( all were very aware of the problem and advised that many of the 996 series thru 2002 have this failure at around 50K miles. Porsche changed the design at the end of 2002, because of the problem. ) and the best I could do was $20K for a new engine. Talked with a porsche consumer rep who told me " it was a problem we were aware of and necessitated a design change, but your car is out of warrantee and it is your problem." As a long time Porshe enthusiast and currently own 2 of them, I am a little put out with situation. I am 68 years old and the C4 is my daily driver, never raced or abused and well maintained I expected much more from the car and the company than that. If that had happened to my Toyota tundra I feel sure they would have made it good. I will still tell you Porsche is the best driving car on the road but I have reservations about their current committment to the customer. Sorry for the negativity, but beware of buying the 2002 and older 996"s unless you have an extra 20 grand to spend on an engine.

[DaveFL76]

Here's a completely unscientific, statistically unsound indicator of how common (or uncommon) a 996 engine failure is:

I just read through all 155 posts. This thread has been viewed just shy of 69,000 times so far and 10 people have reported failures that resulted in a new engine. Granted, not all 69,000 views were different people but it should give us a gut feel for the rate of failure.

Can moderators get a good idea of the number of unique users have 996s or have viewed this thread? Might make it a little more statistically relevant.

[A34735]

My first P is a 1999 996.

I bought it in Sep 2010 from Fremont Porsche for $24.5K, with 62.4K miles on the clock. I got the service history from the previous owner - which was on the button. The 60K 'major service', incl a new belt, a $3.6K job in California had been done at 57K miles.

I drive it most days to work, a 92 mile round trip, have clocked up 7K in 6 months: I'm hooked...will only drive Ps till I die (hopefully 25 years from now!)

I then discovered the IMS story, was seriously thinking about spending 4K to replace it with the LN replacement. Next I took it for a pre-race day inspection at Kahlers. The tech there told me the IMS fails around 30K miles: if you've gotten past that, forget it. He also said IMS failures give adequate warning, and in any case, a rebuild is only (!)$10K.

BTW...the oil (Mobil 1) is still clear, pale yellow. This is the first car I've owned where the oil isn't black....have to love those engineers!

My intent is to drive this baby into the ground, I'll post when it dies....

Edited May 17, 2011 by Loren
removed offending language

[A34735]

Few cars of that vintage were reliable...and Freddy/Ferdy designs of that era were typical.

In my 40 years of driving (first 30 in UK/EU, next 10 in US) I was stranded on the roadside too often (AA/RAC membership was always paid up before insurance). Cars #1, #2 were Mini, Austin - all piles of s**t. Car #3, a Chevette wasn't bad (despite obvious design flaw with headlights). I blew the head gasket (at indicated, but unbelievable 110 mph) on the M1 at 2am. (the only good part of this story was rescue by a dentist's daughter in an Audi Quattro - but that's another story!)

Then the Lancia - an expensive mistake! I never knew if I'd get to the destination when I set out: Most memorable was breaking down on Bodmin Moor, the A303, at 2am (Another story..) But I still have zero faith in Italian cars, wouldn't touch a Ferrari with yours...(though the new FIAT 500 looks good, may try it).

Later I went French: Citroen, Peugeot and Renault.

To date the most comfortable car I've ever owned was a Citroen. The hydropneumatic suspension was amazing. Turn on the ignition, the car rose up 4 inches. There was even a lever to jack up the car if you needed to change a tire: Monsieur Eiffel, I salute you and your descendents. (the classic 2CV was also a perfect design. My French stepgrandmother used to run over rabbits (for pate) when she wasn't rescuing downed RAF fliers (she got a Croix de Guerre for her heroism, another story!).

The DS (today still a ground-breaking design - who had the first eye level brake lights?). If I could buy one for my daily 90+ mile commute on the 680/880, I would.

Then Mercedes, BMW and Porsche reacted to the Jap invasion - quality and reliability improved by leaps and bounds (thank you Dr Demming!).

So cut a long story short. I drive my old, used 996 90+ miles a day. I've added 7K miles to the 63K on the clock. Drive it, don't worry about it. Previous poster's message:

As the owner of my third 911, a 996, I take exception to the notion that concerns re engine/reliability issues may have sth to do with a shift in buyer demographics. True, Porsche may have expanded it's market in recent years. I would suspect, however, that more of their newbies are driving Boxters, not 911's. At any rate, as the owner of a 1968 911 my father bought new, and the former owner of a 1979 911SC (my wife only lets me have 2 at a time), I can tell you that the concerns re Porsche engine reliability are real. I have driven Porsches now for 23 years. I personally am sick and tired of the many glitches, flaws, reliability concerns not covered by the factory, etc one sees with Porsches and at the prices they command. You name it - leaking engine seals, chain tensioners going bad, leaking valve covers getting oil in heat exchangers, head studs, RMS leaks, etc. the list is not a short one. I have a RMS leak now! - which the dealer will fix at my expense whenever the clutch goes bad. THis is clearly a design flaw. Whatever the excuse, they should fix it, no questions asked. I am not an apologist for the marque, as so many seem to be. It is only because these persistent quality control issues come with the extreme joy of driving one that I remain a loyal owner.

[txhokie4life]

My first P is a 1999 996.

I bought it in Sep 2010 from Fremont Porsche for $24.5K, with 62.4K miles on the clock. I got the service history from the previous owner - which was on the button. The 60K 'major service', incl a new belt, a $3.6K job in California had been done at 57K miles.

I drive it most days to work, a 92 mile round trip, have clocked up 7K in 6 months: I'm hooked...will only drive Ps till I die (hopefully 25 years from now!)

I then discovered the IMS story, was seriously thinking about spending 4K to replace it with the LN replacement. Next I took it for a pre-race day inspection at Kahlers. The tech there told me the IMS fails around 30K miles: if you've gotten past that, forget it. He also said IMS failures give adequate warning, and in any case, a rebuild is only (!)$10K.

BTW...the oil (Mobil 1) is still clear, pale yellow. This is the first car I've owned where the oil isn't black....have to love those engineers!

My intent is to drive this baby into the ground, I'll post when it dies....

I have personally seen four IMS failures.

30k, 60K, 92k, 105k

two manuals and two tips. 2.5L, 2.7L, 3.2Lx2

I know of several others in/around Austin/Houston/Dallas.

I have also seen many other failure modes.

cracked cylinder liners, hydrolock (aos?), multiple spun bearings, d chunks, water pumps, broken timing chains, old fuel.

I'm sure Jake has even more anacdotal evidence to support the numerous engine failures, and relative random nature of mileage

and configurations.

Mike

[Cefalu]

I have a 1999 C2 Cab with 61,000 miles. Has been well maintained and has been pretty trouble free. I had a relay go bad in the secondary air injection and that is the only problem I have had. It was a $20 fix

However, it needed a new clutch, so I installed a new RMS, LNE ceramic IMS bearing and a new AOS.

The old RMS was not leaking but I wanted to upgrade to the newest 997 version. The old IMS bearing was not exhibiting any signs of failure and the upgrade was purely for peace of mind. The IMS bearing flange seal was leak free. In fact there was no oil between the flange and the bearing. The old bearing was in perfect condition, tight and the seals were good.

The AOS was not showing any signs of failure either, but it is very difficult to get to, and while I was in there replacing the clutch it made sense to swap it out.

All done now and the car runs great (again)

[2003996C2]

I hope I am doing this correctly - first timer. I'm in the process of having my 03 996 C2 motor rebuilt and am hoping to do it in a way that will reduce the possibility of having to do it again soon. I use it primarily as a track car at HMS, PBIR, Sebring & Daytona. Tires are Sport Cups, StopTech ST40 brakes PF-1 pads (front), Fabspeed headers, sport cats & cold air intake. No software tweaks. My engine apparently spun a bearing at a Chin event at HMS. I got it shut down and to the shop without catastrophic damage. The 4-5-6 bank scavenger pump was torn up and the valves, piston and related hardware on cylinder 5 were damaged. I had an X51 oil pan (pan & baffle only) put on the car a couple months before. I've spent many hours reading on the LN Engineering, Flat 6, Accusump websites and many forums and haven't been able to reach a consensus about how best to address the high lateral g-load oil starvation and general M96 reliability issues. I've committed to the following:

LN IMS retrofit kit

LN deeper sump spacer kit, magnetic, plug, etc.

AASCO LWF w/Sachs Spring loaded clutch disk

160 degree t'stat

Items I'd like input on:

Is the LN sump spacer kit compatible with the X51 pan? LN has a low opinion of the X51 pan w/out the full X51 engine mods?

Has anyone used an Accusump system and / or the Motorsport two chamber AOS to deal with oil pressure fluctuations while cornering?

If so, what were the results?

Any other ideas?

Thank you.

[JFP in PA]

I hope I am doing this correctly - first timer. I'm in the process of having my 03 996 C2 motor rebuilt and am hoping to do it in a way that will reduce the possibility of having to do it again soon. I use it primarily as a track car at HMS, PBIR, Sebring & Daytona. Tires are Sport Cups, StopTech ST40 brakes PF-1 pads (front), Fabspeed headers, sport cats & cold air intake. No software tweaks. My engine apparently spun a bearing at a Chin event at HMS. I got it shut down and to the shop without catastrophic damage. The 4-5-6 bank scavenger pump was torn up and the valves, piston and related hardware on cylinder 5 were damaged. I had an X51 oil pan (pan & baffle only) put on the car a couple months before. I've spent many hours reading on the LN Engineering, Flat 6, Accusump websites and many forums and haven't been able to reach a consensus about how best to address the high lateral g-load oil starvation and general M96 reliability issues. I've committed to the following:

LN IMS retrofit kit

LN deeper sump spacer kit, magnetic, plug, etc.

AASCO LWF w/Sachs Spring loaded clutch disk

160 degree t'stat

Items I'd like input on:

Is the LN sump spacer kit compatible with the X51 pan? LN has a low opinion of the X51 pan w/out the full X51 engine mods?

Has anyone used an Accusump system and / or the Motorsport two chamber AOS to deal with oil pressure fluctuations while cornering?

If so, what were the results?

Any other ideas?

Thank you.

There is no reason the LN pan spacer would not fit, only question is does the pickup spacer lower the pickup enough to get it near the sump floor. As for the X51 package, just adding the sump will do little other than increase the sump’s holding capacity slightly. The full X51 added an additional scavenger pump in the heads and a “northwest passage” oil line to get the oil from the extra pump back to the sump quicker, which is a major plus. Someone is making a similar kit to retrofit non X51 engines, but it requires removing and machining the cam cover for the bypass line, which can be tricky as the cam covers are matched to the heads and not easily replaceable should the process get screwed up or need to be removed. The kit is also very expensive.

The Accusump is a major benefit when cornering causes oil starvation, but it is not a guarantee, engines with them still can and do fail but usually for other reasons. It also requires running a smaller filter that needs to be changed more frequently.

[c70Pete]

the x51 oil pump and line is what is needed for sure...

don't mean to hijack the thread here but I understand that adding a LWFW can potentially damage out your crank! have you looked into this?

[JFP in PA]

I have, and I would definitely recommend against using a light weight single mass flywheel unless the rotating assembly, and the flywheel, are fully balanced as a unit before the engine is assembled.

A lot of people seem to think that they can simply slap on an X51 sump cover and all is well, when the reality is that the sump cover is probably the least important component in the upgrade.

[c70Pete]

I have, and I would definitely recommend against using a light weight single mass flywheel unless the rotating assembly, and the flywheel, are fully balanced as a unit before the engine is assembled.

A lot of people seem to think that they can simply slap on an X51 sump cover and all is well, when the reality is that the sump cover is probably the least important component in the upgrade.

dumb question here... what exactly is the rotating assembly... is that not on the flywheel... is it a separate component?

as for the X51 baffled pan.. its does provide *some* benefit that's for sure... but I definitely agree that it is only the 1st (and IMO necessary step) in upgrading the oiling system... I'm curious if there are folks who have done both X51 AND deep sump pan (which holds about 1/2 quart extra only) that have seen more stable pressures in corners where oil pressure was previously unstable. I know of an outfitter here in Canada that makes a sump kit that holds a *complete quart* of oil with spacing hardware and that would certainly help to ward off starvation a bit better than just 1/2 a quart; if the oil your engine needs is suspended in one corner of the engine during a high g corner it will never make it back to the sump and hence never pumped to where it is needed... (this is where complete X51 oiling kit comes into play - pumping it back into sump) and the theory of having a full extra quart means that it was never pumped and is ready as "reserve"... many are doing this but I haven't heard any feedback that shows a change in oil pressure; I have an X51 pan only and *think* I see a SMALL difference but I will do more testing this summer that's for sure as I have made less than scientific observations.

[Loren]

"rotating assembly" is the crankshaft, rods, front pulley, and flywheel.

I always have these balanced (weight matched, and lightened) when rebuilding an engine. It will add years and RPM to the engine.

[JFP in PA]

I have, and I would definitely recommend against using a light weight single mass flywheel unless the rotating assembly, and the flywheel, are fully balanced as a unit before the engine is assembled.

A lot of people seem to think that they can simply slap on an X51 sump cover and all is well, when the reality is that the sump cover is probably the least important component in the upgrade.

dumb question here... what exactly is the rotating assembly... is that not on the flywheel... is it a separate component?

as for the X51 baffled pan.. its does provide *some* benefit that's for sure... but I definitely agree that it is only the 1st (and IMO necessary step) in upgrading the oiling system... I'm curious if there are folks who have done both X51 AND deep sump pan (which holds about 1/2 quart extra only) that have seen more stable pressures in corners where oil pressure was previously unstable. I know of an outfitter here in Canada that makes a sump kit that holds a *complete quart* of oil with spacing hardware and that would certainly help to ward off starvation a bit better than just 1/2 a quart; if the oil your engine needs is suspended in one corner of the engine during a high g corner it will never make it back to the sump and hence never pumped to where it is needed... (this is where complete X51 oiling kit comes into play - pumping it back into sump) and the theory of having a full extra quart means that it was never pumped and is ready as "reserve"... many are doing this but I haven't heard any feedback that shows a change in oil pressure; I have an X51 pan only and *think* I see a SMALL difference but I will do more testing this summer that's for sure as I have made less than scientific observations.

The “rotating assembly” is the pistons, rods, rings, bearings, wrist pins & associated hardware; plus the flywheel.

The X51 sump cover and baffles assembly does add about ½ quart of capacity, or about 5% of the total. While the extra oil is a good thing, if you stop and think about the fact that it is such a small portion of the total available oil. A properly done competition oil system works with three factors: The quality of the oil (the rating or grade of it), the condition of the oil (its temperature, shear condition, viscosity), and the location of the oil (where it is inside the engine). Because these cars are capable of tremendous cornering forces, if the oil is hot, thin, and most of it is trapped up in the engine assembly; what is left can easily get stood up (literally) on the sidewall of the engine cases, and your pump momentarily runs dry. Not a good thing. Because of the “boxer” design of the engine (flat opposed six), a lot of the oil trying to drain back into the sump gets “stuck” in the cylinder bank towards the outside of a given corner, and the oil in the sump stands up on the same wall of the sump. Not a good thing.

The full X51 system helps collect that oil and get it back into the sump, lessening the change of the pickup becoming uncovered, and bearings being without oil; which is obviously a very good thing.

[c70Pete]

I have, and I would definitely recommend against using a light weight single mass flywheel unless the rotating assembly, and the flywheel, are fully balanced as a unit before the engine is assembled.

A lot of people seem to think that they can simply slap on an X51 sump cover and all is well, when the reality is that the sump cover is probably the least important component in the upgrade.

dumb question here... what exactly is the rotating assembly... is that not on the flywheel... is it a separate component?

as for the X51 baffled pan.. its does provide *some* benefit that's for sure... but I definitely agree that it is only the 1st (and IMO necessary step) in upgrading the oiling system... I'm curious if there are folks who have done both X51 AND deep sump pan (which holds about 1/2 quart extra only) that have seen more stable pressures in corners where oil pressure was previously unstable. I know of an outfitter here in Canada that makes a sump kit that holds a *complete quart* of oil with spacing hardware and that would certainly help to ward off starvation a bit better than just 1/2 a quart; if the oil your engine needs is suspended in one corner of the engine during a high g corner it will never make it back to the sump and hence never pumped to where it is needed... (this is where complete X51 oiling kit comes into play - pumping it back into sump) and the theory of having a full extra quart means that it was never pumped and is ready as "reserve"... many are doing this but I haven't heard any feedback that shows a change in oil pressure; I have an X51 pan only and *think* I see a SMALL difference but I will do more testing this summer that's for sure as I have made less than scientific observations.

a lot of the oil trying to drain back into the sump gets "stuck" in the cylinder bank towards the outside of a given corner, and the oil in the sump stands up on the same wall of the sump. Not a good thing.

yes but I thought with x51 with the walls built in *around* the tube it forces a much smaller perimeter and keeps the oil in place during high g cornering so the pick up tube has something to suck in... it also has the baffles that open and close to trap oil in that little box round the pickup tube... in a non-x51 pan I can see the oil being cornered on the far wall away from the pick up tube but I don't believe this is happening with x51 pan... unless of course that corner is so long and sweeping and you are generating serious g force for a long time so that it picks up all the oil the x51 pan has collected and now its stuck on top of one of the heads waiting for the g-forces to stop so it comes back down... <- that can definitely happen and from what I'm told will blow the motor; so the question is whether putting in an extra litre of oil with a deeper sump pan makes that condition less likely and I think it does..

btw ... I never knew the x51 pan with baffling allows an extra 1/2 litre of oil... interesting...

[c70Pete]

"rotating assembly" is the crankshaft, rods, front pulley, and flywheel.

I always have these balanced (weight matched, and lightened) when rebuilding an engine. It will add years and RPM to the engine.

so unless you take apart your engine to balance all the above parts *with* the new LWFW your saying don't do it?

[Loren]

"rotating assembly" is the crankshaft, rods, front pulley, and flywheel.

I always have these balanced (weight matched, and lightened) when rebuilding an engine. It will add years and RPM to the engine.

so unless you take apart your engine to balance all the above parts *with* the new LWFW your saying don't do it?

I would not. But everyone must weigh the risks and make their own decision.

[c70Pete]

"rotating assembly" is the crankshaft, rods, front pulley, and flywheel.

I always have these balanced (weight matched, and lightened) when rebuilding an engine. It will add years and RPM to the engine.

so unless you take apart your engine to balance all the above parts *with* the new LWFW your saying don't do it?

I would not. But everyone must weigh the risks and make their own decision.

ok... thx for clarifying... that's why lots of the engines that have this mod added eventually give out early.. but not all though... its a crapshoot

[2003996C2]

I hope I am doing this correctly - first timer. I'm in the process of having my 03 996 C2 motor rebuilt and am hoping to do it in a way that will reduce the possibility of having to do it again soon. I use it primarily as a track car at HMS, PBIR, Sebring & Daytona. Tires are Sport Cups, StopTech ST40 brakes PF-1 pads (front), Fabspeed headers, sport cats & cold air intake. No software tweaks. My engine apparently spun a bearing at a Chin event at HMS. I got it shut down and to the shop without catastrophic damage. The 4-5-6 bank scavenger pump was torn up and the valves, piston and related hardware on cylinder 5 were damaged. I had an X51 oil pan (pan & baffle only) put on the car a couple months before. I've spent many hours reading on the LN Engineering, Flat 6, Accusump websites and many forums and haven't been able to reach a consensus about how best to address the high lateral g-load oil starvation and general M96 reliability issues. I've committed to the following:

LN IMS retrofit kit

LN deeper sump spacer kit, magnetic, plug, etc.

AASCO LWF w/Sachs Spring loaded clutch disk

160 degree t'stat

Items I'd like input on:

Is the LN sump spacer kit compatible with the X51 pan? LN has a low opinion of the X51 pan w/out the full X51 engine mods?

Has anyone used an Accusump system and / or the Motorsport two chamber AOS to deal with oil pressure fluctuations while cornering?

If so, what were the results?

Any other ideas?

Thank you.

There is no reason the LN pan spacer would not fit, only question is does the pickup spacer lower the pickup enough to get it near the sump floor. As for the X51 package, just adding the sump will do little other than increase the sump’s holding capacity slightly. The full X51 added an additional scavenger pump in the heads and a “northwest passage” oil line to get the oil from the extra pump back to the sump quicker, which is a major plus. Someone is making a similar kit to retrofit non X51 engines, but it requires removing and machining the cam cover for the bypass line, which can be tricky as the cam covers are matched to the heads and not easily replaceable should the process get screwed up or need to be removed. The kit is also very expensive.

The Accusump is a major benefit when cornering causes oil starvation, but it is not a guarantee, engines with them still can and do fail but usually for other reasons. It also requires running a smaller filter that needs to be changed more frequently.

Thank you. I think I have a good handle on everything but would really like to hear from someone with personal experience installing and using the Accusump system. I've read their and LN's postings and have talked at length to folks at both companies but can't find any feedback from someone using it on any M96. Thanks again.

[JFP in PA]

We have several customer's running the Accusump system, some which we installed. Is there something specific you want to know?

[JFP in PA]

"rotating assembly" is the crankshaft, rods, front pulley, and flywheel.

I always have these balanced (weight matched, and lightened) when rebuilding an engine. It will add years and RPM to the engine.

so unless you take apart your engine to balance all the above parts *with* the new LWFW your saying don't do it?

I would not. But everyone must weigh the risks and make their own decision.

ok... thx for clarifying... that's why lots of the engines that have this mod added eventually give out early.. but not all though... its a crapshoot

+1 on Loren's comments. This is what was left of a factory X51 motor running a lightweight flywheel.............