IMS question.
 

Can the ims be upgraded on the boxsters as a precaution... looking at on 00 at 39k miles and don't want to have it go out as soon as i buy it...

Contact Jake Raby, board sponsor at www.flat6innovations.com or click on the big logo, upper right hand corner.

Mike, I have a '00 S with 38k. I went through all the same anxiety that you're going through. I'm a long time bmw driver and always stayed away from the boxsters for the very same thing you're worried about. Do a search of my screen name and you'll find some very good posts from other members back in January to me about my worrying about ims failures. Hopefully it will put your mind at ease.

sean :-)

Yes, no and costly
 

Can it be done, yes.

Is it cost effective, no. You currently have to split the case apart to get at the IMS bearings though someone is reputed to be working on a version that allows a replacement with merely the motor removed from the chassis and no need to go inside the crankcase.

Just like any other car...some fail. And just like any other car...drive it, enjoy it, break it and fix it in that order if it happens.

My Boxster S '01 has had lots less problems than my '01 Acura TL and none serious in trouble or $. My prior '99 Boxster had no problems. My prior 914 couldn't stay out of the shop.

Start funding your own multi-$B 'Bailout Plan' just in case, and then forget about it.

If it goes KaBoom, you have a headstart and if not, you have a nice little egg waiting for you.

http://www.lnengineering.com/ims.html

I have a very detailed explaination of all the differences between the various IMS's from 97-08, and what can be done.

You have a few options:

If it's a single row bearing IMS, yes, you can remove the bearing and replace it with our IMS retrofit kit (available from Flat 6 Innovations).

If it's a dual row bearing IMS, as posted earlier, you can only update it by tearing the engine down and sending us your IMS, which we then modify, and returned upgraded.

There isn't a good way to identify what kind of IMS you have, single row or double row, short of pulling the flywheel and doing a physical identification. At this point, what can be done regardless of model year is that you can remove the seal off the front of the IMS "sealed" bearing, to allow better lubrication of the bearing. I have an explaination of why on the page I linked to above. It's best to do this when doing a clutch job, since you have to pull the transmission as well as the flywheel to get access to the IMS.

Fire away if anyone has any questions after reading all the details on our web page.

The only other recommendations I have are that you should change your oil often AND you should use an oil like Royal Purple, or something that has a quality friction modifier, like moly. This will help improving longevity of the IMS bearing once the seal is removed from the front to allow fresh oil to cool and lubricate the bearing.

Charles:

Thank you for the excellent information. That article is so informative and so well presented that it borders on being a scholarly dissertation.

It is so refreshing to find first hand information on the internet.

Regards, Maurice.

No problem, glad you found it informative.

We just got an IMS in that was literally minutes away from failure - the 2.5 engine it came out of actually suffered a rod bolt failure before the IMS and that's why it came apart.

I'll get some video of the IMS bearing out of this one so everyone can see one right prior to failing - it's amazing!

Charles:

Did the connecting rod bolt actually break apart or did it just start to unscrew itself?

How much mileage on the engine?

Any indications of overrevs or was it another cause?

I know of another M96 engine with a similar failure and am trying to compare notes.

Regards, Maurice.

Maurice,

I just answered this same question on the ppbb forums - the bolt indeed broke.

Mileage was 115,000 mi. I'll have to ask what the computer had for over-revs.

I actually updated our IMS page again to include a more sure-fire way of identifying which IMS your engine has. I've had so many discrepancies in what an engine had versus what I thought it should have had, I can't guess which ones are single row bearing IMSs, hence the need to visually identify each one.

I also took some video of the failing IMS bearing as well as some photos of another dual row that was just sent in with 70,000 mi that completely came apart in the engine. It's posted on Youtube:

http://www.youtube.com/watch?v=xvLRMGs-Ti8

As you'll see in the video, it's physically possible to check for how much play there is in the bearing and gauge it's condition.

Charles -Jake, thanks for the great video; it really gives us an insite to how all these parts interplay. I've looked at the PET diagram, but it doesn't show the bearing housing as a separate part...should I assume this part fits into the intermediate shaft?

When you recommend removing the seal for greater lubrication, again, I assume you mean the outer one that you removed in the video?

I won't be tearing my engine down soon, but as an active club DE instructor/some times racer, I am very interested in this topic.

Yes, that's the seal I refer to removing, just like in the video.

The bearing in pressed into the intermediate shaft itself. On the dual row, there's a wire loc that you can see on the outside diameter of the bearing that expands into a matching groove in the bore of the IMS. On the single row, it has a physical circlip that can be removed externally, then the bearing can be pulled out of the IMS. Does that help?

Charles: Thanks for taking the time to give me a detailed answer. It is much appreciated.

The video is worth a million words, especially because it is so well done that it takes a lot of the mystery out of this particular weak point in the M96 engines. It is an excellent supplement to the article on your website.

Keep up the good work! :cheers:

Regards, Maurice.

That's because it wasn't my shop ;)
Happy Boxstering,
Pedro

Thanks again, Charles. As I've said before, you take alot of the mystery out of these engines with your explanations, and now the videos.

The video is worth a million words, especially because it is so well done that it takes a lot of the mystery out of this particular weak point in the M96 engines. It is an excellent supplement to the article on your website.

C'mon. Porsche will not admit that there is any "weak points" in these engines. That is just a vicious rumor spread by BMW, right?

:D

This may be a dumb question, but here goes: Surely, they don't support the whole IMS with a bearing at just one end. There is a bearing at the other end of the IMS, right? What does that bearing look like? Why doesn't it fail?

It's just a plain bearing on the other end. **Correction, as Jake pointed out, it just rides in the case on an oil film.** All the thrust is handled by the ball bearing as well.

Originally, in all the aircooled 911s, the intermediate shaft had plain bearings on both ends with one having a thrust surface, if memory serves me. Interestingly, the GT2, GT3, and Turbo use a shaft like the aircooled one since the engine is so close to an aircooled 964 that was water cooled!

There is no other bearing opposite the failure prone IMS bearing.

There is no bearing insert in the case, the bearing just rides against a machined portion of the case and is lubricated hydrostatically... The cams ride in the heads without bearing inserts as well.. Much like a 36HP VW engine or a 356 engine- No cam bearing inserts.

BTW-this technical discussion is great.

Thanks to all who are contributing.

Has anyone posted a schematic of the engine yet?

:)