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Greetings, new to this forum, not new to forums.....great tools!

I'm the lucky one in this story, my neighbor across the street is not. He has owned since new, a 2002 996 now with 22000 miles and yes, his IMS blew out. He is a pretty decent wrencher and race car driver. As it stands the car is worth just about nothing. He is not in the mood for the $18000 fix. The engine was replaced by Porsche under warrantee after just 7000 miles, and his faith in the marquee is, well, damaged. But, he is willing to throw a grand at the LN kit and try to fix this.....

This is where I come in, I have the lift, and more tools.

So, we have removed the tranny and some of the parts of the bearing...... this is where we are at:

IMG_0308.jpg

IMG_0311.jpg

Yes I know.... the LN website has a picture just like it on it and it says...."If it looks like this, give up."

But, it's pretty much a lawn ornament as it is, and before selling it for scrap or parting it out he, again, is willing to throw a grand at it. So, at this point all I am looking for is some help on the following.

We know about the tensioners, back off the bolts BUT DONT TAKE THEM OUT as you may lose timing. So how far do they come out? Enough to center the shaft?

And this is the big one.... what is the best method to remove the outer race at this point? I don't think the LN puller will help anymore.....my thought is to carefully dremmel it out. I know, crude but better than a lot of banging. There is a slight lip on the race, I thought about fabricating some kind of hooked slide hammer bit..... any thoughts?

Yes, there's crud in the engine. We pulled the pan and found some of it. Notice there's 5 out of the six balls from the bearing in the picture, one is awol.....and so are all the pieces that separated them. We plan on putting a hose on the "out" fitting of the oil filter (haven't done the autopsy on that yet, hope most of the crud is in there) and then with a pump forcing a flushing medium through the engine and just letting it drop out of the bottom before we replace the pan, fill with oil replace filter and install a magnetic oil plug. Run for a minute or two, change oil and filter again.....

Any more thoughts?

Edited by Oscarvan
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The caps are two bright green rubber plugs that are on one end of the cylinder heads. You will find one set on each end of the engine, they look like this: I really need to caution you on attemp

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A couple of serious questions:

  • What year was the new engine installed? Reason I ask is any replacement engine installed after 2005 has a unique "final solution" IMS bearing (has a 22MM center nut) that cannot be removed or replaced with the engine assembled (outer race is larger than the opening in the case).
  • This looks like it failed while running; if it did, are you sure the engine is worth saving? Most are not......
  • If the engine is 2005 or earlier, and the engine is actually salvageable, you may need to very carefully cut the outer race in a couple places with a Dremmel tool using the smallest cut off wheel in order to get it out. This will require using a combination of magnets and a good shop vac to catch as much of the cutting debris as possible so it does not remain in the engine. This may be your only way to get it out, if you (and the engine) are up for it...........

Edited by JFP in PA
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Thanks for the reply....

The engine was replaced March 2005.....

No we're not sure whether the engine is worth trying to save..... It's worth a grand to him to find out.

OK, one vote for the dremmel with small wheel......

Edited by Oscarvan
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Thanks for the reply....

The engine was replaced March 2005.....

No we're not sure whether the engine is worth trying to save..... It's worth a grand to him to find out.

OK, one vote for the dremmel with small wheel......

Problem is that when the IMS begins to "wobble", the car often jumps cam timing, resulting in bent or broke valves, pistons, etc. At that point, spending anything on the IMS retrofit is a waste of money; the engine needs to either be pulled and rebuilt, or replaced as it is "non-serviceable".

Before moving forward, we would pull the plugs and bore scope the engine to be sure you are not throwing good money at what is otherwise a boat anchor. If the engine shows any signs of piston/valve contact, you would be wasting your time and his money.

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Sorry to hear this and see the photos. In spite of what is being said on other popular Porsche forums... IMS failures do occur--and far too often. I have personally met two 996 owners whose cars have suffered catastrophic failures due to IMS bearing failure. In one case the engine was replaced (out of warranty) with a MY06 m96 in October of 2005 at a partly-Porsche-subsidized cost of $13,000+. The owner thought this was a nice upgrade and in fact the engine does run great. Unfortunately it is a "big bearing" motor with the 22mm IMS center nut and thus is not a candidate for the LN Eng retrofit. The owner does not know this and is not particularly interested in the topic.

The second car suffered a total failure as the result of an IMS bearing failure while cruising on the interstate at 70 MPH. The motor shut off and the car coasted to a stop. $15,000 for a rebuild out of warranty, including the IMS retrofit. To add insult to injury... the owner of that car had just spent $3000 on a new clutch months before--and could have added the LN Eng upgrade for less than an extra $1000 while the transmission was off. Now that owner has $35,000 invested in a car that has a resale value of something like $19,000 to $22,000. He has stopped driving the car and is trying to sell it for way more than the market will bear.

Back to your car... The center nut does not appear in your photo... 13mm or 22mm? I have a few comments and concerns:

  1. I think I'm pretty good with a Dremel and those amazing carborundum cutting wheels... but how will you get that bearing out with out ruining the bearing seat? Maybe a thin brass or steel liner to protect the seat? What about damaging the end of the IM shaft itself? How will you retrieve the pieces that fall as they are cut free?
  2. LN Eng suggests installing the new bearing with Loctite (presumably "red") when the seat to bearing fit is compromised.
  3. The LN kit requires the cams be locked in position before beginning the bearing removal process. Even if you got the old bearing out and get a new ceramic hybrid bearing back in... I think the motor would have to be R&R to confirm cam timing before you could spin the crank and cams. Is there another way?

In any case, good luck. I will be watching for updates on what you learn or what progress you make.

...j

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  1. I think I'm pretty good with a Dremel and those amazing carborundum cutting wheels... but how will you get that bearing out with out ruining the bearing seat? Maybe a thin brass or steel liner to protect the seat? What about damaging the end of the IM shaft itself? How will you retrieve the pieces that fall as they are cut free?

I learned this trick from Jake Raby, and it works. From time to time, you encounter an OEM IMS bearing that falls apart when you try to extract it, leaving the outer race behind. You need to very carefully cut the outer race with the Dremel, usually in more than one spot, in order to get it out. Strong magnets and a good shop vac collect most, if not all, of the debris during the process, pulling the sump cover and flushing clean oil downwards get the rest. While not pretty, the method works; and I have yet to see an alternative way that is better.

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Good info! Thanks.

The failure happened at low RPM/Speed. When last shut down the engine was running fine, except for the "funny noise". We are cautiously optimistic that timing has not been lost.

Tuesday is dremel day.... I have a few large magnets.

Will post results.

Edited by Oscarvan
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You might check the timing before you commit to the IMS replacement by pulling the green plugs on back side of the cams and

see if they line up at TDC with the notch on the heads. Note you make two revolutions of the crank for one complete cam revolution.

This assumes that you can turn the crank and the ims tube will rotate -- but this could be risky.

Alternatively, pull the plugs and put a boroscope down each tube -- you should be able to see the impact of the valves with the pistons (it will look like

shiny half-moons on the pistons) -- if you see this -- something has jumped timing.

If not, you maybe in luck.

Mike

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I just threw 19k into a 2003 C4, borderline whether it was worth it or not. Gotta love Porsche to part with the dough in these cases, that's for sure. My 993 was bulletproof compared to the 996. Still, I live and never learn ;-)

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OK, we are progressing. Managed to cut the outer race about 80% using dremmel and carbide cutting bit. Will post picture of bit later for those that come behind..... Finally figured out the "lay of the land". There was a snap ring, the groove is now obvious. Snap ring is gone.... More work tomorrow. Oh, did open the oil filter.....much "silver dust"......

Edited by Oscarvan
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$19,000 for repairs to your MY03... makes me think about a guy at the autocross that had the fastest, nastiest sounding Lotus Europa I had ever seen or heard. Later in the day I walked over to his "pit" and was stunned to see no engine under the hood--how'd he pull it out so fast I wondered... Then I noticed a blue anodized adapter ring attached to his transaxle, and a tiny, gallon paint-can-sized Mazda 13B rotary bolted to the adapter. My guess is that the Mazda "transplant" was cheaper than rebuilding the Lotus/Renault/Cosworth twin cam 4 the Europa came width. I guess you have more affection for Porsche than he had for Lotus :) I hope you get many issue free miles from your rebuild.

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OK, we are progressing. Managed to cut the outer race about 80%.... Finally figured out the "lay of the land". There was a snap ring, the groove is now obvious. Snap ring is gone.... More work tomorrow. Oh, did open the oil filter.....much "silver dust"......

Take your time; when doing one of these, there is no advantage in trying to rush it.

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Agreed....

OK, another question... the chain tensioners.... a few threads did nothing.... a few more and they came out.... is that bad? Sprockets are now centered, and we certainly aren't going to turn the engine or horse it around until the tensioners are back in....

Wish I had a good service manual......

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Have you boroscoped the cylinders?

you really want to know if the valves have been bent which would be an indication of having lost timing.

mike

When the noises started, my friends wife was driving. She pulled over and shut it down. The car was trucked to the dealer for assessment. When it came back to my friends house he started it, briefly, before he put it in the garage. At that point it ran fine. Based on that we are assuming there is no MAJOR damage. What long term effects the debris from the failed bearing may have is another story.

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Agreed....

OK, another question... the chain tensioners.... a few threads did nothing.... a few more and they came out.... is that bad? Sprockets are now centered, and we certainly aren't going to turn the engine or horse it around until the tensioners are back in....

Wish I had a good service manual......

Not really. I do need to ask if you locked the engine at TDC, and locked down the cams before pulling the tensioners?

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Agreed....

OK, another question... the chain tensioners.... a few threads did nothing.... a few more and they came out.... is that bad? Sprockets are now centered, and we certainly aren't going to turn the engine or horse it around until the tensioners are back in....

Wish I had a good service manual......

Not really. I do need to ask if you locked the engine at TDC, and locked down the cams before pulling the tensioners?

Nope, asked my bud to get a shop manual, he doesn't have one. Found out about that after the fact. Let's just say we are very careful not to move anything.

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Being careful not to rotate the motor may not matter, the engine internals move due to the spring pressures on the cylinders with any open valves trying to unload, and there will always be open valves. This is why the correct procedure is to lock the engine at TDC with a pin thru the front crank pulley, then pull the cam plugs and attach the cam locking fixture before releasing the tensioners. I think you are already in trouble. I have had a couple cars flat bedded into the shop after their owners pulled the tensioners without locking the motor down; the result was always the same, the cam timing had moved and needed to be "re-allocated" in Porsche speak........ Three chain motors are more susceptible to this problem than five chains; but the five chains can jump time as well.

Edited by JFP in PA
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Being careful not to rotate the motor may not matter, the engine internals move due to the spring pressures on the cylinders with any open valves trying to unload, and there will always be open valves. This is why the correct procedure is to lock the engine at TDC with a pin thru the front crank pulley, then pull the cam plugs and attach the cam locking fixture before releasing the tensioners. I think you are already in trouble. I have had a couple cars flat bedded into the shop after their owners pulled the tensioners without locking the motor down; the result was always the same, the cam timing had moved and needed to be "re-allocated" in Porsche speak........ Three chain motors are more susceptible to this problem than five chains; but the five chains can jump time as well.

In order for it to jump time a chain would actually have to skip teeth on a sprocket right? Not having seen them, I am assuming the teeth are 1/4" to 3/8" deep? It would take a lot of movement to skip a tooth over the entire sprocket.... Or am I missing something here?

On a side note..... how involved is "re-allocation" ? I'm assuming it is done on the top end?

Edited by Oscarvan
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Yes, there are multiple places (sprockets) where this can happen, depending upon if it is a three or five chain motor.

I think you need to pull the cam plugs and look at where the cams are in relation to each other. One of the biggest issues you face is that the engine has only one position (TDC) where the slots in the cams line up, and with the IMS removed, you cannot rotate the engine. You may be forced to have to pull the cam covers, remove the cams (to unload the valves), and then try to get everything back to the TDC position, then start reassembling. But at this point, you do not know if it will even run (or for how long) in its current state.

At this juncture, I really think you need to stop, bore scope the engine to see if it shows signs for piston to valve contact, which is a common phenomenon when an IMS dies. If that is in fact the case, you need to pull this engine and take the heads off anyway, so going through the cam allocation set up would be a total waste of time as it will need to be done a second time when the engine is reassembled outside the car, if it can be reassembled........

Edited by JFP in PA
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"On a side note..... how involved is "re-allocation" ? I'm assuming it is done on the top end? "

Camshaft "allocation" is an overly complicated process on the M96/97. In a nutshell, it requires holding the four cams in a fixed position in relation to the crankshaft, and then installing the cam drives (the OEM service manual takes about 15 or so pages to describe how to do it and the fixtures and tooling required, depending upon the model year). Not for the faint of heart; and it requires some pretty specific tooling. It is hard enough on and engine stand, a nightmare with the engine in the car. If one or more of the chains was damaged when it jumped, or if the sprocket was damaged, you are far better off pulling the engine................

Edited by JFP in PA
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Thanks, JFP I appreciate you taking the time to answer my questions. So, how "tall" are the teeth on the sprockets and how easy is it for them to jump? We are pretty sure timing was good when we started to disassemble, and other than the releasing of the tensioners there hasn't been any movement.

It's not my call, but my friend wants to install the new bearing. I will insist we check the marks on the cams before we fire it up. I deduce from what you say that if the timing is off there can/will be piston/valve contact.

One more question: Standing behind the car looking forward, which cylinder is #1?

Edited by Oscarvan
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The teeth are about 3.5 mm tall. On three chain engines they can jump more easily. 5 chain engines it is much less likely. It is still worth removing the cam caps to verify the timing marks regardless.

Yes, if the timing is off, you can have piston/valve contact and possible meltdown.

Here is the cylinder designation for you:

cylinders.png

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The teeth are about 3.5 mm tall. On three chain engines they can jump more easily. 5 chain engines it is much less likely. It is still worth removing the cam caps to verify the timing marks regardless.

Yes, if the timing is off, you can have piston/valve contact and possible meltdown.

Here is the cylinder designation for you:

cylinders.png

Cool, how do I know how many chains I have? And, do you have a diagram showing where the caps are? I would have to manually pull the engine to TDC to get the cams lined up.... I guess I would feel it if it was locking up...

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