Here We Go, Another 996 Ims Replacement!

[logray]

First of all thank you to everyone that has posted excellent information about this repair (shark attack over on rennlist, wayne @ pelican, etc.). I've wrenched on cars since my first VW and found this to be of a great help to be able to read other peoples experiences. It made getting this far a snap.

Started working on the car yesterday and have the trans out and flywheel off.

I ordered a bearing kit from LN. I'm also going to replace the RMS and fix a pesky AOS leak while I'm in here. The jury is still out on the revised chain tensioners.

Later today the oil gets drained, then the chain tensioners pulled, and lastly the IMS hub flange removed to reveal the bearing.

Any opinions on the clutch (35k) and original flywheel (70k miles)? I'm contemplating a new DMFW to rule out another component for an engine that wobbles a little (mostly noticable at idle), but then at the total bill, what's a new clutch cost anyways...

The flywhel snaps back into place after rotating either way per the TSB and the clutch looks like there is still some wear left on the pads, but I'm certainly no expert!

The IMS will be replaced one way or the other...

The RMS will also be replaced.

Flywheel condition look ok? It has 70k miles. Just some sandpaper and good for another 30k?

The clutch still has some pad left, about 35k on it.

The pressure plate looks a little worn.

I replaced the AOS a while back and need to get back in there with new factory clamps and a new bellows. There is also a leaking hose at the top of the unit I will replace.

Everyone seems to have white crud in this cavity, apparently due to the area not being sealed to water and the elements.

[logray]

The ims bearing... looks and feels to be in tact, although there appears to be some play around the outside of the tube outside the bearing (normal?), and some oil certainly making it's way through the bearing...

Tensioners pulled. The passenger side did not "pop out" when I removed it like the drivers side did.

Drivers side

Passenger side

[rb101]

There should be no pop as they should slide out smoothly. Replace all 3 tensioners, I had scoring on the IMS and 1-3(D), the 4-6(P) was clean, but wanted a full set of new ones. Make sure you get the older style for the IMS chain(996-105-180-54). There is a service bulletin that you can't mix the new style IMS adjuster/tensioner and the old style pad. I put the new style one in and replaced it with the older style after 3K. When I pulled it out, it looked like the piston was out of its bore and only the spring was keeping it together. Order new crush washers as they don't come with the adjusters.

[logray]

Thanks for the advice on the tensioners. Ah-hem. <clears throat>. I hope I didn't just royally screw up here, and need to retime after removing only the 2 tensioners followed by the ims cover.

3rd tensioner? Where would that be located? I removed the one accessible under drivers side facing downwards and the second one on the opposite side near the oil filter, which I had to losen a clamp for a hose to get to. Yikes.

[Dharn55]

The third tensioner is on the 4-6 bank of cylinders on the top of the head. You have to remove the airbox and loosen a clamp for the power steering hoses to get at it. I forget whether you have to remove the AC Compressor or not. It is a bear to get at. Uses the same size socket as the other tensioners, which barely fits in there. The new/replacement tensioner uses a "allen wrench" to removal, i.e. a hex head driver instead of a socket. This tensioner puts pressure on the IMS at the opposite end from the bearing/flange, but LN and Flat 6 say to remove it for the bearing upgrade.

Now as for the new/replacement tensioner for the IMS to Crank. I saw rb101's earlier post regarding this tensioner and the problems he had with the new style tensioner. However, I have spoken to both Charles at LN Engineering and Jake Raby at Flat 6 Innovations, and they both say to use the new style tensioner. Charles says he uses it in his 99 boxster engine that he races. So they both say to ignore the tech bulletin from Porsche and use the new style tensioner, However rb101's experience provides a question. To date I have not bought a new set as I am worried about the IMS to Crank tensioner.

The other challenge is that the old style tensioner is only available from Germany, at least that has been the case for the past month or two. Apparently there are only a few left in Germany. And if your order it it take 3-5 weeks to get! I think you can expedite the shipment, but that costs a bit. I checked with Sunset, Suncoast and Porscheoemparts.com and they all said it had to be rodered from Germany if you wanted the old style.

I have been waiting to resolve the question on the tensioners so that I can order them and have them on hand before I try to do an IMS bearing upgrade. Don't want to have the car apart for several weeks.

Edited May 25, 2010 by Dharn55

[logray]

...The third tensioner is on the 4-6 bank of cylinders on the top of the head. You have to remove the airbox and loosen a clamp for the power steering hoses to get at it. I forget whether you have to remove the AC Compressor or not. It is a bear to get at. Uses the same size socket as the other tensioners, which barely fits in there. The new/replacement tensioner uses a "allen wrench" to removal, i.e. a hex head driver instead of a socket. This tensioner puts pressure on the IMS at the opposite end from the bearing/flange, but LN and Flat 6 say to remove it for the bearing upgrade...

Gotcha. I am actually leaning towards not replacing the tensioners as well, price and lead time being the biggest issues for me.

I read some other posts where people have replaced their IMS bearing by only removing the two easily accessible tensioners.

At this point since I've removed my ims cover after only removing 1-3 (drivers) and the main tensioner (passenger) and leaving 4-6 intact (top of head) - for anyone who has done this procedure before - do you think I need to a.) retime at this point (I'm now leaning toward pulling the caps to check timing before firing up), b.) should I proceed to try to remove the third tensioner for 4-6, or c.) just leave 4-6 in place and proceed with pulling the bearing (as I've seen others have had success doing this).

For what it's worth I didn't hear any suspicious chain skipping noises during removal and the ims bearing cover came off with ease and I can also easily slide it back on, although I see the ims tube might be slightly off center towards the drivers side and up slightly.

[logray]

I could certainly welcome the advice before proceeding, but I "think" I might be ok here not removing 4-6 based on a couple threads...???

http://www.renntech.org/forums/index.php?/topic/29492-my-diy-nightmare/

http://forums.rennlist.com/rennforums/996-forum/549133-im-going-in-alone-lne-retrofit-bearing-7.html (sorry for post to another forum)

quoted from above "Are you replacing all the tensioners?... [reply] Tensioners: Not sure yet. I really want to get it back together But I will have to make this call after I pull them. Even so you can not get to all of them, so in a way, whats the point?"

I guess maybe he didn't realize he could get to it, you can "get to" anything with a certain amount of time and effort.

And this PIC confirming that I've removed B and C for the crank and 1-3.

[txhokie4life]

...The third tensioner is on the 4-6 bank of cylinders on the top of the head. You have to remove the airbox and loosen a clamp for the power steering hoses to get at it. I forget whether you have to remove the AC Compressor or not. It is a bear to get at. Uses the same size socket as the other tensioners, which barely fits in there. The new/replacement tensioner uses a "allen wrench" to removal, i.e. a hex head driver instead of a socket. This tensioner puts pressure on the IMS at the opposite end from the bearing/flange, but LN and Flat 6 say to remove it for the bearing upgrade...

Gotcha. I am actually leaning towards not replacing the tensioners as well, price and lead time being the biggest issues for me.

I read some other posts where people have replaced their IMS bearing by only removing the two easily accessible tensioners.

At this point since I've removed my ims cover after only removing 1-3 (drivers) and the main tensioner (passenger) and leaving 4-6 intact (top of head) - for anyone who has done this procedure before - do you think I need to a.) retime at this point (I'm now leaning toward pulling the caps to check timing before firing up), b.) should I proceed to try to remove the third tensioner for 4-6, or c.) just leave 4-6 in place and proceed with pulling the bearing (as I've seen others have had success doing this).

For what it's worth I didn't hear any suspicious chain skipping noises during removal and the ims bearing cover came off with ease and I can also easily slide it back on, although I see the ims tube might be slightly off center towards the drivers side and up slightly.

We always pull each one as well as the caps. But on a 996 that upper one is a royal PITA.

Not only did you have to remove the AC, but the power steering line as well.

On an 02 I just finished -- the tensioner had an inset hex head --- and not the normal 32mm like the rest.

Cheap piece of mind to insure the cams are still in time.

We also like to prefill the tensioners with oil by compressing them immersed in oil, and releasing.

I'd like to figure if there was a way to lock the cams in place -- and then not have to remove that 4-6 tensioner -- but

I haven't convinced myself it would work.

the downside is pretty high.

mike

[logray]

Thanks Mike. So your advice is, even though I've already removed the ims hub cover, proceed to tear apart a/c compressor/etc. and remove the upper 4-6 before proceeding.

Then pull the bearing and replace.

I am now heavily leaning towards pulling the caps at this point - even though I didn't hear anything "chain skipping like" while removing the tensioners - once I've got it back together in order to check the timing.

I guess the worst that could happen with this "insurance" by pulling the caps is that I verify the timing is off, and either attempt that procedure myself or bring it to a shop to get it timed - so I don't blow it up and make a small oops into a huge one. At the expense of a few caps.

Make sense?

[txhokie4life]

Thanks Mike. So your advice is, even though I've already removed the ims hub cover, proceed to tear apart a/c compressor/etc. and remove the upper 4-6 before proceeding.

Then pull the bearing and replace.

I am now heavily leaning towards pulling the caps at this point - even though I didn't hear anything "chain skipping like" while removing the tensioners - once I've got it back together in order to check the timing.

I guess the worst that could happen with this "insurance" by pulling the caps is that I verify the timing is off, and either attempt that procedure myself or bring it to a shop to get it timed - so I don't blow it up and make a small oops into a huge one. At the expense of a few caps.

Make sense?

Thinking about how it should work -- you want to lock the crankshaft at TDC, then do as best you can to prevent any of the chains from changing their relative position.

I don't know that removing the hub cover has actually moved anything. I think the concern is that if you do pull the bearing and one chain is taunt will it somehow

cause some imbalance which cause some "spin".

Frankly I don't know....

I'm seriously considering building two cam locking tools -- putting one on each side locking the cams in place,

then locking the crankshaft in place -- then arguably there is no way anything can move unless you jolt

the chains with the IMS. And in that case the chains would be under tension and less likely to move.

I maybe have to bounce this thought off of Jake and Charles and see what they think. Would be a whole lot easier than

getting to that #4-6 -- especially on the 996 engines.

I think the real issue is -- nobody has enough experience/knowledge to know for sure what exactly is the best thing to do.

So in lieu of that -- take every precaution you can.

Mike

Edited May 25, 2010 by txhokie4life

[rb101]

The new/replacement tensioner uses a "allen wrench" to removal, i.e. a hex head driver instead of a socket.

Now as for the new/replacement tensioner for the IMS to Crank. I saw rb101's earlier post regarding this tensioner and the problems he had with the new style tensioner. However, I have spoken to both Charles at LN Engineering and Jake Raby at Flat 6 Innovations, and they both say to use the new style tensioner. Charles says he uses it in his 99 boxster engine that he races. So they both say to ignore the tech bulletin from Porsche and use the new style tensioner, However rb101's experience provides a question. To date I have not bought a new set as I am worried about the IMS to Crank tensioner.

The other challenge is that the old style tensioner is only available from Germany, at least that has been the case for the past month or two. Apparently there are only a few left in Germany. And if your order it it take 3-5 weeks to get! I think you can expedite the shipment, but that costs a bit. I checked with Sunset, Suncoast and Porscheoemparts.com and they all said it had to be rodered from Germany if you wanted the old style.

The new 4-6 tensioner is an allen wrench and I think it might clear or at least release tension without moving the A/C compressor (have not confirmed)

The new IMS tensioner piston does not have a pin to limit the maximun travel as the older style does and only has the chain pad and the spring to keep everything together. It looks from the tech bulletin diagram that the new style pad sits closer to the tensioner then the old style. When I pulled the new tensioner out after 3K miles of use, it looked like the piston was fully extened and would have been leaking oil. I know the old style tensioner worked for 105K, the new was an unknown entity. It's only $70 for some piece of mind.

I got the last one in the US mid March

Gotcha. I am actually leaning towards not replacing the tensioners as well, price and lead time being the biggest issues for me.

At this point since I've removed my ims cover after only removing 1-3 (drivers) and the main tensioner (passenger) and leaving 4-6 intact (top of head) - for anyone who has done this procedure before - do you think I need to a.) retime at this point (I'm now leaning toward pulling the caps to check timing before firing up), b.) should I proceed to try to remove the third tensioner for 4-6, or c.) just leave 4-6 in place and proceed with pulling the bearing (as I've seen others have had success doing this).

For what it's worth I didn't hear any suspicious chain skipping noises during removal and the ims bearing cover came off with ease and I can also easily slide it back on, although I see the ims tube might be slightly off center towards the drivers side and up slightly.

The 1-3 and 4-6 tensioners are in the states and I would replace them as you have everything apart. The IMS can be changed later, but I would change them all out.

If you have the engine pinned at TDC, pulled IMS and 1-3 tensioner and IMS flange, I doubt anything has jumped timing. I would pull the 4-6 before you proceed on pulling the IMS bearing so there is not tension on the other side of the IM Shaft and oil pump drive.

Edited May 25, 2010 by rb101

[logray]

...you want to lock the crankshaft at TDC, then do as best you can to prevent any of the chains from changing their relative position. I don't know that removing the hub cover has actually moved anything. I think the concern is that if you do pull the bearing and one chain is taunt will it somehow cause some imbalance which cause some "spin"...

I hear you about precautions to avoid total melt down the first time I turn the key, I suppose if I can get to 4-6 and remove it - then why not.

Removing the caps to verify timing, extra insurance.

For the best insurance of locking the cams out I've looked at this zdmak tool (engine installed?) and this one (engine removed?), but seriously $200? I'm would lean towards making my own tool as well.

[logray]

I got a pm from a guy that replaced the IMS on his 996 without touching the 4-6 tensioner. Then again it sounds like he might be more of a gambling man than I - as he didn't pull the caps to verify timing or lock out the cams.

Over on this boxster thread there are two people that said they did not pull the third tensioner, and they seem to suggest the most important one to releave tension is the crankcase tensioner (passenger side).

"...One must remove the chain tensioner on the back right side leading from the IMS to the cam shaft as well as the chain tensioner from the crank shaft to the IMS..."

and

"...one each for the chains from IMS to the heads, and one for the chain from the crank to the IMS. If you had loosened the tensioner for the IMS drive chain, this would have been pretty easy..."

and

"...loosened the two chain tensioners (the Crank-IMS one and the IMS-Cam one, on the transmission side of the engine). I left the tensioner on the opposite side alone..."

In that thread they (including Jake Raby) also go on to explain that the damage is done once the hub flange is removed... if the tensioners have not been removed or relieved of tension.

I would think if I could at least get to the 4-6 tensioner and give it a few spins to release the tension (as recommended by Wayne's pelican DIY versus removal - which even he does not describe losening a third), I would be better off. I'll poke around today and see if I can get to it without dropping the engine.

Edited May 25, 2010 by logray

[logray]

...When I pulled the new tensioner out after 3K miles of use, it looked like the piston was fully extened and would have been leaking oil. I know the old style tensioner worked for 105K, the new was an unknown entity. It's only $70 for some piece of mind. The 1-3 and 4-6 tensioners are in the states and I would replace them as you have everything apart. The IMS can be changed later, but I would change them all out.

Sorry for my confusion, I thought you were recommending the new style tensioner? It sounds like you had issues with the new, perhaps because you did not replace all three at the same time? And the old tensioner lasted you 105K?

If you have the engine pinned at TDC, pulled IMS and 1-3 tensioner and IMS flange, I doubt anything has jumped timing. I would pull the 4-6 before you proceed on pulling the IMS bearing so there is not tension on the other side of the IM Shaft and oil pump drive.

Yep that's where I'm at - I agree on trying to release tension on 4-6 - like it was said earlier - extra insurance when I start banging around on the bearing and shaking things around a bit.

[logray]

Hey would you look at that! 4-6 tensioner!. I can see how people skip this one. The A/C definately comes out or loosened off to get at this.

Funny thing is I can get an extension in there, but the 32mm socket would be impossible without moving things.

On the flip side I've been innundated with people who have been successful with the ims replacement without touching it.

[rb101]

...When I pulled the new tensioner out after 3K miles of use, it looked like the piston was fully extened and would have been leaking oil. I know the old style tensioner worked for 105K, the new was an unknown entity. It's only $70 for some piece of mind. The 1-3 and 4-6 tensioners are in the states and I would replace them as you have everything apart. The IMS can be changed later, but I would change them all out.

Sorry for my confusion, I thought you were recommending the new style tensioner? It sounds like you had issues with the new, perhaps because you did not replace all three at the same time? And the old tensioner lasted you 105K?

If you have the engine pinned at TDC, pulled IMS and 1-3 tensioner and IMS flange, I doubt anything has jumped timing. I would pull the 4-6 before you proceed on pulling the IMS bearing so there is not tension on the other side of the IM Shaft and oil pump drive.

Yep that's where I'm at - I agree on trying to release tension on 4-6 - like it was said earlier - extra insurance when I start banging around on the bearing and shaking things around a bit.

I would recomend to replace all the tensioners with new. Only the IMS tensioner changed in style the other two are the same type with minor updates. At 105K, both my IMS and 1-3 tensioners were badly scored and didn't operate smoothly. I really didn't need to replace 4-6, but did anyways. I feel that that using the new style (997) IMS tensioner with the older style chain pads is a bad idea. Porsche put out that service bulletin for a reason.

[logray]

Interesting, didn't notice this wear on the ims flange cover until I cleaned it up. Someone ran it with low oil? Also a few bits of what looks to be sealant inside the ims bearing tube placed to right of pitted area for your viewing pleasure...

New RMS went in.

With my custom tool.

Edited May 25, 2010 by logray

[rb101]

That's an interesting picture. There is nothing that touches the IMS flange at that location, might have been a bad casting that was too low for the machining to remove.

Edited May 25, 2010 by rb101

[Wayne R. Dempsey]

Hi guys. I have a *great* new method for replacing the bearing that doesn't involve removing the tensioners or using the camshaft tool. I've discussed it at length with Charles (LN Engineering), and he also agrees that it's very clever and should work pretty well. We're testing it right now on a 996 with a busted IMS bearing. The balls on this bearing were completely loose - I had only seen one with this much damage. The car only has 31,000 miles on it too. I've got a photo posted right here: http://forums.pelica...-check-out.html . Tomorrow I'm going to try to remove the bearing with Charles' tool - we're hoping it will come out, but since the bearing race is completely gone, it may get stuck in there and require some other persuasive techniques to remove.

I'll keep everyone posted, and I should have a new article up on the web next week that will simplify the entire process. I'm excited about the method, but I don't want to let the cat out of the bag until we fully test everything.

Oh, I also have a complete article on the chain tensioners that some of you may find useful: http://www.pelicanparts.com/techarticles/Boxster_Tech/16-ENGINE-Camshaft_Swap_and_Chain_Tensioner/16-ENGINE-Camshaft_Swap_and_Chain_Tensioner.htm

-Wayne

Edited May 26, 2010 by Wayne R. Dempsey

[logray]

Wayne I can only guess that a new tool is in our future!

I chickened out a little but want to make sure this is as trouble free as possible. That and since I'm still waiting on the bearing...

I checked the WSM and it says to install a new sealing ring on the ims shaft flange, you have to roughly:

1.) lock @ TDC.

2.) turn primary chain tensioner out of the left hand crankcase.

3.) turn secondary chain tensioner out of the right hand cylinder head (1-3)

4.) then proceed to remove the shaft flange.

So even for the sanctioned procedure to remove the hub flange there is no mention of removing the chain tensioner for 4-6 behind the A/C.

I removed the cam caps and marked current position (note that for some positions there are already marks on the block and end of the shaft indicating you are at TDC). Some of the caps are a real bear to get at.

Hey does anyone know if the caps go on dry or should I put some sealant around the outside lip? It seems to be a pressure fitting and might not require sealant.

Edited May 26, 2010 by logray

[txhokie4life]

Wayne I can only guess that a new tool is in our future!

I chickened out a little but want to make sure this is as trouble free as possible. That and since I'm still waiting on the bearing...

I checked the WSM and it says to install a new sealing ring on the ims shaft flange, you have to roughly:

1.) lock @ TDC.

2.) turn primary chain tensioner out of the left hand crankcase.

3.) turn secondary chain tensioner out of the right hand cylinder head (1-3)

4.) then proceed to remove the shaft flange.

So even for the sanctioned procedure to remove the hub flange there is no mention of removing the chain tensioner for 4-6 behind the A/C.

I removed the cam caps and marked current position (note that for some positions there are already marks on the block and end of the shaft indicating you are at TDC). Some of the caps are a real bear to get at.

Hey does anyone know if the caps go on dry or should I put some sealant around the outside lip? It seems to be a pressure fitting and might not require sealant.

At TDC -- both sides exhaust should be in line with the cylinder head/valve cover line. One side is at 12 oclock, the other at 6 oclock.

Once around the horn on the crank and you'll be at 6 oclock / 12 oclock-- note the slot is actually slightly

off center relative to the case and this is how you can tell 12 oclock from 6 oclock.

I can never remember which side is which -- on the Boxsters I have a tool which shows the alignment -- and I'll note that the other side is

either horizontally in or out relative to the cylinder head/valve cover line.

One more full turn and you will be back at 12 oclock/ 6 oclock..

The plugs dry fit with a solid tap of a rubber mallot.

m

Edited May 26, 2010 by txhokie4life

[logray]

So in other words, once the ims bearing and tensioners are back in, two full cranks (720 degrees) and the marks I made in pen should line up again?

[txhokie4life]

So in other words, once the ims bearing and tensioners are back in, two full cranks (720 degrees) and the marks I made in pen should line up again?

yes -- 2 crank revolutions is 1 cam revolution.

mike

[Ahsai]

With my custom tool.

Nice custom RMS tool! Could you please share how to fabraicate it?

[logray]

Nice custom RMS tool! Could you please share how to fabraicate it?

Check out this post, that has a link to a site with the specs... other than that get creative at your local hardware store with a 3" outside diameter PVC fitting and another section of pipe to fit inside as a stop... there are other threads out there describing what parts to get. Then you can gently tap in place with a dead blow until it reaches the stop.

Optionally place a plank of wood on the back side of the tool, drill some holes that will fit into the shaft, and use bolts to draw the RMS in similar to how the factory tool does it.