IMS flange/cover off..how to check bearing?

[car]

I'm in the process of replacing clutch and RMS. I'm tempted to replcace the IMS bearing, but have decided that if the old one is ok, then I would leave it alone as I'm concerned about the extracting process. I have the flange off, have loosened both the chain tentioners and tried to see if there were any play in the bearing from moving the bolt. Is that the correct way to check for play? I have a 2000 C-4 double row bearing with 84K miles. Thanks in advance.

[phillipj]

Call Jake Raby at "Flat 6 Innnovations". Google it...

[car]

After 2 hours iof search and some interesting reading, I've found the answers below. Thanks.

And from Jake Raby

"The bearing can be inspected by simply "parking" the engine @ TDC, removing the chain tensioners and the IMS bearing flange. The tensioners must be pulled or the IMS will have no support and will become off center in the engine making reassembly more difficult.

Once the flange is removed the bearing can be checked for play/ wear and tight spots that indicate the races/ rollers are beginning to fail. At the same time the outer grease seal can be removed to allow the engine's lubricant to reach the bearing to more thoroughly lubricate it. "

Edited January 11, 2010 by Loren
made video viewable here

[car]

BTW...bearing checked out great! No play whatsoever and turns smoothly at 84K miles. I'm just going to replace the flange seal and call it good.

Edited January 11, 2010 by car

[phillipj]

Awesome...Thanks for the update....

[jthailer]

BTW...bearing checked out good at 84K miles so I'm just going to replace the flange seal and call it good.

I have read a lot about IMS, but I don't really know what it actually does. Can someone explain it.

Thanks,

[rb101]

BTW...bearing checked out good at 84K miles so I'm just going to replace the flange seal and call it good.

I have read a lot about IMS, but I don't really know what it actually does. Can someone explain it.

Thanks,

The IMS essentially takes the timing from the crank and send it out to the cams. The IMS sits below the crank in the engine. There is a chain that goes from the crank to the IMS. The IMS has two other chains that transfer the timing to the cams. The back one (by the bearing, flywheel side) that goes to the exhaust cam on cylinders 1-3. The other end of the IMS has a chain that goes to the exhaust cam on cylinders 4-6 (this end also runs the oil pump). If the bearing fails, the IMS has no support in the rear and the chains can/will jump timing. This timing jump causes the pistons to strike the valves and mayhem ensues, causing a total engine failure.

Rick

99 996C4

87 944S

[Dharn55]

When I had the engine out of my 2000 C4 to fix the intermix problem (cracked head) the new tool for extracting the dual row bearing was not yet available. I did the check of the bearing described, and replaced the flange/seal with the newer style, and removed the outer seal on the bearing. The bearing did not appear to have any problems. Actually the last time I had the engine out the tool was available, but I was struggling with an oil pressure problem and did not want to spend the $600 for the updated bearing not knowing if I was going to solve the other problem.

I have now solved it and kink of wish I did the bearing upgrade. Next time I have the engine or trans out I think I will defintely do the upgrade. The $600 is notheing compared to the cost of an engine.

[car]

I hear ya buddy....and it was a tough call for me not to do it. The cost was never the deciding factor, but rather "if it ain't broken don't mess with it." I must be lucky cause after 84K miles, that bearing was like new. Gives me no reason to think that it can't do another 40K. Besides....dropping the gearbox was not that bad (my first time). If better data on the failure rate comes out in the future, I can always invest another 6 hours to do it then. Thanks all!

Edited January 12, 2010 by car

[sehorntx]

I also have my engine out currently repairing cracked cylinder head (both sides). 1999 C2 76K. Removed IMS flange this weekend and mine looks good as well. No play or unusual sound. Spins well. Still contemplating retrofit from LN Engineering.

[rb101]

I also have my engine out currently repairing cracked cylinder head (both sides). 1999 C2 76K. Removed IMS flange this weekend and mine looks good as well. No play or unusual sound. Spins well. Still contemplating retrofit from LN Engineering.

I replaced mine a few weeks ago @ 105K miles. It looked fine in the engine with no wobble. I now have it sitting on my computer desk, without the seals and dry of engine oil, it rattles a lot if I shake it and if I spin it really fast, it some times makes a buzzing. I think it would have survived for another 30K. But, if you have your engine or transmission out for another purpose, you might as well replace it. I see $600 as a cheap replacement for a critical part.

Edited January 12, 2010 by rb101

[jthailer]

BTW...bearing checked out good at 84K miles so I'm just going to replace the flange seal and call it good.

I have read a lot about IMS, but I don't really know what it actually does. Can someone explain it.

Thanks,

The IMS essentially takes the timing from the crank and send it out to the cams. The IMS sits below the crank in the engine. There is a chain that goes from the crank to the IMS. The IMS has two other chains that transfer the timing to the cams. The back one (by the bearing, flywheel side) that goes to the exhaust cam on cylinders 1-3. The other end of the IMS has a chain that goes to the exhaust cam on cylinders 4-6 (this end also runs the oil pump). If the bearing fails, the IMS has no support in the rear and the chains can/will jump timing. This timing jump causes the pistons to strike the valves and mayhem ensues, causing a total engine failure.

Rick

99 996C4

87 944S

What have they changed in the 987/997 engine design that eliminates this problem?

[JFP in PA]

BTW...bearing checked out good at 84K miles so I'm just going to replace the flange seal and call it good.

I have read a lot about IMS, but I don't really know what it actually does. Can someone explain it.

Thanks,

The IMS essentially takes the timing from the crank and send it out to the cams. The IMS sits below the crank in the engine. There is a chain that goes from the crank to the IMS. The IMS has two other chains that transfer the timing to the cams. The back one (by the bearing, flywheel side) that goes to the exhaust cam on cylinders 1-3. The other end of the IMS has a chain that goes to the exhaust cam on cylinders 4-6 (this end also runs the oil pump). If the bearing fails, the IMS has no support in the rear and the chains can/will jump timing. This timing jump causes the pistons to strike the valves and mayhem ensues, causing a total engine failure.

Rick

99 996C4

87 944S

What have they changed in the 987/997 engine design that eliminates this problem?

They eliminated the IMS shaft entirely in 2010............

[1schoir]

What have they changed in the 987/997 engine design that eliminates this problem?

The entire Intermediate Shaft and its bearing have been designed out of the latest iteration of the engines.

Porsche has never admitted that there is a serious problem with the IMS bearing itself, which, from my understanding, suffers from two fatal flaws: wrong bearing for this application, and sealed bearing which, when it loses its lubrication, quickly fails.

Regards, Maurice.