IMS center bolt

[WhiteyII]

Yes that's what I found when I pulled the seal for inspection. I certainly wasn't expecting
what I found. Anybody know what appears to be a patch/repair is in the photo?
Installed the new bearing, crankcase pan, RMS, flywheel and clutch today, tranny tomorrow.....can you help me understand why low mileage could have contributed to this failure? I don't get it, but glad I didn't like the feel of my clutch, that's why I went in to try and fix that and found what I found. Probably could have gone around the block a couple more times, you think.......

[Homeoboxter]

Originally Posted by WhiteyII

Yes that's what I found when I pulled the seal for inspection. I certainly wasn't expecting
what I found. Anybody know what appears to be a patch/repair is in the photo?

Weird... My guess is somebody has already tried to pull the bearing out using a bearing puller and one of the arms of the puller broke the casting. This would explain the unusual failure of the bearing, it may have got damaged at the same time. Is it the original?

[elgyqc]

Originally Posted by WhiteyII

.....can you help me understand why low mileage could have contributed to this failure? I don't get it....

I don't get it either, but reading on this and other forums it is often said that IMSB problems happen more often in M96 engines that have not been driven a lot and not driven hard. Is there data to back this up? I don't know.

This is from the LN engineering site.

"Remember, not driving your car or worst yet, not driving it like Porsche intended can make the problem worse. Although a greatly debated subject, most experts agree that more frequent oil changes with a quality 5w40 motor oil like Driven DT40 every 6 months or 5,000 miles is a good first step. Secondly, actually driving your Porsche more often and avoiding higher gears to keep the revs above 2500-3000 rpm is another good step to take to improve the life of the ball-bearing in the intermediate shaft. Although there is limited data, the general trend is that lower mileage vehicles with infrequent oil changes or driven light-footed (as in run at low speed/engine rpms) are most likely to suffer a failure rather than those cars that are driven hard and well-maintained."

[Homeoboxter]

Originally Posted by elgyqc

I don't get it either, but reading on this and other forums it is often said that IMSB problems happen more often in M96 engines that have not been driven a lot and not driven hard. Is there data to back this up? I don't know.

One possible explanation might be that the oil that gets trapped inside the IMS and hence in the bearing is overused and dirty as it`s not replaced with the oil changes. Also, the gas that seeps through the bearing during cooling-warm up cycles is crankcase gas, which contains CO2 and other potentially corrosive chemicals coming from burnt gas and oil. Now, if you leave your car unused for years, the bearing sits half way submerged in this dirty oil inside the tube. Being half way exposed to the oil for years may cause an uneven wear pattern which might lead to future failure?

This is just a theory that I just came up with, don`t take it for granted
But for this reason I added a "drain hole" to the IMS where the trapped oil can escape.

An additional note: my car had 100k miles and spent 11 years in a garage with the engine seized. The IMSB was original and in a perfect shape. But the oil it was sitting in was black and dirty.

[JFP in PA]

Originally Posted by Homeoboxter

But for this reason I added a "drain hole" to the IMS where the trapped oil can escape.

A better and permanent fix would have been to install a plug behind the bearing, as is done in all IMS Solution retrofits. The IMS shaft tube is weak enough without drilling drain holes into it.

[Homeoboxter]

Originally Posted by JFP in PA

A better and permanent fix would have been to install a plug behind the bearing, as is done in all IMS Solution retrofits. The IMS shaft tube is weak enough without drilling drain holes into it.

Actually I drilled the sprocket through while pinning it to the shaft:



The idea is that centrifugal force is constantly pulling oil from the tube through this hole while receiving oil from the crankcase through the open end.

[piper6909]

Originally Posted by Homeoboxter

One possible explanation might be that the oil that gets trapped inside the IMS and hence in the bearing is overused and dirty as it`s not replaced with the oil changes. Also, the gas that seeps through the bearing during cooling-warm up cycles is crankcase gas, which contains CO2 and other potentially corrosive chemicals coming from burnt gas and oil. Now, if you leave your car unused for years, the bearing sits half way submerged in this dirty oil inside the tube. Being half way exposed to the oil for years may cause an uneven wear pattern which might lead to future failure?

This is just a theory that I just came up with, don`t take it for granted
But for this reason I added a "drain hole" to the IMS where the trapped oil can escape.

An additional note: my car had 100k miles and spent 11 years in a garage with the engine seized. The IMSB was original and in a perfect shape. But the oil it was sitting in was black and dirty.

While we're on the subject of drilling and modifications; From my research, I believe the best, cheapest, and simplest way to keep fresh oil in the bearing is to tap a hole in the opposite end of the IMS shaft behind the oil pump and remove both seals from the IMSB. This way oil will actually circulate.

Full disclosure: I have not done any such mods to mine, nor have I changed the IMSB. But if I decided to do it, that's the route I'd go.

Yes, I'm aware of the DOF from LNE. While it's good, it's not the simplest nor cheapest. Plus, I'm a bit uneasy about having a pressurized external oil hose. My brother had an Audi with an external oil line. Unbeknownst to him, it ruptured and within seconds of the oil light coming on the engine was toast. The oil was pumped out that quickly.

[Homeoboxter]

Originally Posted by piper6909

While we're on the subject of drilling and modifications; From my research, I believe the best, cheapest, and simplest way to keep fresh oil in the bearing is to tap a hole in the opposite end of the IMS shaft behind the oil pump and remove both seals from the IMSB. This way oil will actually circulate.

Full disclosure: I have not done any such mods to mine, nor have I changed the IMSB. But if I decided to do it, that's the route I'd go.

Yes, I'm aware of the DOF from LNE. While it's good, it's not the simplest and cheapest. Plus, I'm a bit uneasy about having a pressurized external oil hose. My brother had an Audi with an external oil line. Unbeknownst to him, it ruptured and within seconds of the oil light coming on the engine was toast. The oil was pumped out that quickly.

I personally don`t like the idea of modifying the original oil lines, regardless of being external or internal, by adding a "leak" to the system. Especially by punching a hole right at the oil pump. In general, I don`t think it`s necessary.

[piper6909]

Originally Posted by Homeoboxter

I personally don`t like the idea of modifying the original oil lines, regardless of being external or internal, by adding a "leak" to the system. Especially by punching a hole right at the oil pump. In general, I don`t think it`s necessary.

I hear ya. The "leak", as you call it, would drip back into the sump. It's the same as all the other oil passages.

Everyone has their own comfort level, and you're certainly not wrong.

[Homeoboxter]

Originally Posted by piper6909

I hear ya. The "leak", as you call it, would drip back into the sump. It's the same as all the other oil passages.

Everyone has their own comfort level, and you're certainly not wrong.

I meant a leak causing a drop in the oil pressure. An engine oil circulation system is designed such that the oil pump is able to compensate for the oil loss at the bearing/bearing journal clearances. The pump`s capacity is calculated by the engineers such that it can keep up in all circumstances, high temperature, low rpm, low viscosity, partially worn bearings, etc. Here comes the user, and hits a hole with a mallet right into the heart of this delicate system. Most likely the loss is negligible and won`t cause oil starving, still, it sounds super sloppy and unprofessional to me. But it`s just my thinking, it`s totally fine if someone is ok with it