mgordon18

OK. So what are we even talking about here? If you have an early 997 with the replaceable bearings, and you've paid someone to drop the transmission and pull out the IMS, are you really going to just remove the seal? You're going to replace the unit with one of the aftermarket "solutions."

Done and done.

gpjli2

I'm with you. Op's recent round of threads gives me a headache. Other than in the 05's, where replacement bearing makes sense I guess, ims failure just doesn't happen often enough to warrant this much anxiety. Painful to read this stuff. I hope op gets past this. Or sells it. There are some things you just will never have control over.

user 72902

I think the IMSB seal can be removed from all model years. It's the seal facing the transmission that is removed.

Lvt19672

What is IMS???

voda

Then don't read it! This is a 997 forum. This is a 997 question/thread. If you don't like to look at facts and would rather bury your head in the sand, then by all means do. You're the one choosing to click the mouse to select the topic and read the thread. Solution for your headache is easier than the solution for IMS issues.

Flat6 Innovations

Sure. Remove the flywheel, remove the IMSB flange and the seal is staring right at you.

Time has proven that the M97 engines only suffer IMSB failures when tracked. There's a reason for this and the fact that the M96 IMSB fails more on the street and less on the track.

As we disassemble more and more M97 specimens due to other failures we see fewer and fewer worn IMSb units in the M97 engines that have not gone to the track. Unless its a track car, religiously change the oil and IF you do a clutch, then remove the seal. Otherwise drive.

mgordon18

Interesting Jake. Thanks. Good to know.

So it seems that you are saying that the Carrera S engines are less prone to failure than the base Carrera's? Why would that be?

And how much track time are we talking about here? A few track events per year? A dedicated track car? How much is too much?

Flat6 Innovations

No, base models and S models share the same internals. The only differences are found with bore size, chamber volumes and camshafts, in general. Either of them has the same IMSB and the same deficiencies.

Don't confuse what I stated here as meaning that we do not see IMSB failures with M97 engines, because we do, BUT they are much, much, much less than the M96 engines. Funny thing is I can count on one hand what the internal differences are between the M96 and M97 engine, as it is virtually the same.

The M97 engines have now been in service for over 8 years. The IMSB failures that we see 8 years in with these engines barely registers on the scale with what we saw at 8 years, or even 6 years time in service with the M96 engines. Back in those days we were the only guys researching the IMSB failure and developing fixes for it and comparing the figures today tells us the story.

With an M97 engine I'd be much more concerned with cylinder scoring, broken rod bolts and failed valve seats than any IMSB failure. This is because these are the things that are filling our facility with work today, from the M97 family.

Here is a 2008 997 Base engine with 16K miles on it, female owned and driven with perfect maintenance, never tracked. Yes, that wasn't a Type O, its 16,000 miles on the engine.

myw

JAke is that d chunk failure ?!!

Flat6 Innovations

No, rod bolt failure.. The rod bolt stretched and loosened.. It just fell out and was laying in the sump unharmed.

When the opposing bolt broke, it became Kathleen's Kataclysmic Kalamity.

mgordon18

Jake - with all due respect... This is your business and I'm just some schmoe sitting in my living room watching Jimmy Fallon... but it sounds like you're implying that the M97 has the larger bearings and the M96 has the smaller bearings. In other words, the M96 came first with the small IMSB and the M97 came 2nd with the upgraded IMSB.

I'm hoping you're not saying that. We know that the M96 and M97 engines were produced concurrently - that the M96 was the 325hp base engine and the M97 was the 355hp S engine. And that they both received upgraded IMSBs at some point in early 2005.

Now I assume you really meant that the upgraded bearings are less prone to failure, right?

16K miles on the failed engine doesn't surprise me, actually. I think we've come to some sort of consensus on this board that putting real miles on the engine helps prevent damage, and that "if it's going to fail, it'll fail relatively early in the life of the engine."

I assume the failure above was from a IMS bearing failure? If it is, then it'll be the first one we've had hard, first-person evidence for on a post 2005 car.

------ UPDATE after reading the posts that came in while I was writing this -----
Wait - that 2008 car is NOT an IMSB failure? Why are you using it as an example here?

Flat6 Innovations

There are M96 engines with an M97 diameter IMSB, these are the base models that you refer to. Trust that the case code is the only thing that makes them an M96 engine, and that their internals are almost always the same as the M97, to include the IMSB. It gets very confusing AND thats what the factory/ marketing wanted.

Its simple:
Larger diameter bearings feature higher surface speeds which unload the IMSB at lower engine speeds.
Smaller diameter bearings favor higher engine speeds as they have reduced surface speeds.

No matter what the case code on the engine may be, what matters is the diameter of your IMSB, one of which is 26% larger in overall diameter than the other. In 2005 the car can have either bearing and EVERY directive that you will find about VIN and case codes refelctibg what bearing an engine may have is inaccurate. A visual inspection is required, as we face this over and over again. Even the factory diurectives are proven wrong at least on a monthly basis here.

mgordon18

Gotcha. I understand your terminology now. Thanks for the clarification. Turns out we were both saying the same thing in different ways.

So... what is it about the track that makes the "M97 bearings" more prone to failure? And how much track time are we talking about?

Flat6 Innovations

The higher surface speeds that help the larger diameter IMSB at lower engine speeds also hurt it at higher engine speeds by over-speeding the bearing.

It can happen from one track day, or 100.

mgordon18

Perfect.