DIY IMSB Replacement Questions

Sorry - but I couldn't find the answers to these in one place. I am planning to DIY a new IMSB for my car as preventative maintenance. I am trying to figure out the complete Bill of Material I will need. Are the pressure plate bolts one time use or do I replace them? Are the flywheel bolts one time use or do I replace them? I have the encapsulated bolts for the IMSB flange and the LN Pro installation kit. Any other special items I need? I will evaluate the clutch condition after inspection - what is the clutch disc wear limit (thickness)? TIA for the voice(s) of experience. A little nervous about this but it actually looks pretty straightforward and I have a lift so....how hard can it be?

So partially answering my own question, it appears flywheel bolts are one time use but the pressure plate bolts may be reused. And I found some info on clutch disk wear limits on Renntech though the gist of that thread is "just replace it".

Buy new pressure plate bolts....they are specialized fasteners, so if you screw one up removing it, you won't have a replacement on hand. When I had to go into my 944, I had to drill a few out, and I spent 1/2 day chasing something down that would work at local hardware stores. Just get new ones and have them on hand.

Is it necessary to drain the engine oil? Will oil run out of the IMSB flange when removed?

May I ask... And don't take this the wrong way, but... Why not just let a professional do it? You're saving 1000 dollars but have the potential to have to put out 15k invade you make one small mistake. I've put engines into cars, done turbo builds, etc. but this is something that I would leave to a professional.

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The reason why I work on my own cars is two fold. 1. I love getting out in the garage and doing the work. Gets me away from my normal life, away from a computer. 2. Why pay somebody else to do the job for you and they almost never do it as well as I do? This way I know what was done right, where there was an issue, and I learn a lot, but mostly I can't find people to do it the way I want it done. There are a lot of hack mechanics out there.

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Why pay someone else to live your life when you could live it yourself. As a first time DIY, I've already experienced that working on these cars is almost as much fun as driving them and makes you appreciate them even more.

Just buttoned up mine. Seems like you will need a power bleeder for clutch slave. I've bled many many cars the conventional "pump the pedal" way and this is a first time I stumble upon a system that needs a pressure bleeder. Correct me if I'm wrong though. Anyway, building mine out of Weed Spray Tank

Yes, I am of the Paul and Slakker attitude about this work. I have been quoted a very good price by an Indie, but it really doesn't look like a super difficult job (though I recognize it is super important to get it right). I also want the time and opportunity to evaluate the clutch, evaluate the transmission mount, and then proceed accordingly at my pace and my price. I have a bit of experience working on cars as a hobby, I have a nice shop, I have a lift, I'm retired so I have more time than money, etc., etc. Still curious about the oil thing - do I have to drain it?

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Yes drain the oil The oil level normally sits about 1/2 way up the center of the IMSB at rest. Also the heads will drip from the cam plug holes if not drained first.

I thought I had read the IMS is submerged (which makes me wonder why we need external lube or a carbon bearing that performs well when not lubricated...???). Appreciate the input and voice of experience.

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Stock IMS is sealed and doesn't take advantage of the engine oil system.

I respect and applaud everyone who tackles this on a diy setting. I don't want to come across as being douchey or anything. Just my opinion. Friggin Internet has this forum has me bitten with ims bearing night terrors haha.

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I unbolted my slave and hung it out of the way. It is much easier to unbolt it with the trans partially dropped. Same putting it back just be sure to get the rod into the pivot hole.

This might help

Also one of these really helps if you are on a lift. You can adjust the engine height and tilt a little to help with trans alignment.

I just got my 10mm triple square tool (why in hell would Porsche do this?) and made sure I could get that bolt out so it wouldn't bite me later. Thanks for the diagram. And I had forgotten about that nifty adjustable engine support. I think I have access to a lift table to put the trans on and will fiddle with engine angle using a floor jack but that support bar would be better. Anyone have one to loan or rent???

"I just got my 10mm triple square tool (why in hell would Porsche do this?) " To insure their "stealerships" will have plenty of work, or at the very least to make it as difficult as possible for anyone else to do the work...Why else?

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That's because the IMS is submerged or partially submerged in oil (depending on your oil level) only when the engine is off. When the engine is running, the oil gets pumped to parts all over the engine so the engine will drop some.

OK, makes sense. Oil level drops while it is circulating in the engine. Sure must be a lot of oil mist inside there at all times though. The submerged IMS should help with any startup oiling problems though.

Yes, mist and splashed oil.

Do I need any special sealants? IMS flange to engine case? I see Pelican mentions green Loctite for the stud. What did you use?

I finished this project this morning with the first startup after the IMSB replacement. I have not driven the car yet, but so far all seems well. I started and ran the engine for about 3 seconds, waited a little bit, started again and got oil pressure. No rattles either time. I had the battery connected and disconnected several times because I was also doing some work on the power seats. Perhaps because of this I got ABS and PSM failure codes. A little later I also got a CEL which was caused by me forgetting to plug in the MAF - doh! I was able to clear these codes with my OBD tool and they have not returned. My thoughts on this project in hopes it will help others; - this old thread was helpful and encouraging: https://rennlist.com/forums/996-foru...s-bearing.html - I read the LN instructions and the RND instructions and watched the Bentley video, plus all I could read. These are not specific about whether they are working on a 3 chain or 5 chain engine. I think there are differences in what you do to prep for the IMSB replacement between these two designs and it would have helped if they had been more specific (or I had been more knowledgeable??). - Confused about the 3 chain/5 chain thing, I removed the A/C compressor to access a tensioner and then didn't need to remove it. Removing this compressor is a bitch the first time but I bet I could get it off the car in 15 - 20 minutes start to finish now. - The RMS replacement is tricky without a dedicated tool. I messed with the seal trying to get it square until I ended up with it too far into the recess. I then had to buy another seal. Get a tool if you can. - At times I wished I had the support bar tool because working under the car became a PIA but I think the ability to tip the whole thing down (limited with a support bar) outweighed the benefits of the bar. Tipping the engine down really helps AOS work and tipping the assembly really helps access to the top bell housing bolt and the clutch slave. - I had trouble getting the clutch slave into the hole and was puzzled why but it turned out the rubber boot was just too tight in the hole. A little liquid soap on the edge fixed that. I used the RND roller bearing, maybe just to be different. Here is the completed job.

Well done. It is encouraging to see people complete this project as a DIY. Any notable items or issues you came across that you did not see in the other 2 guides you used? How has the car been running so far?

Not really, except I now know why all the guides show "engine removed for clarity". I think if I had it all to do over I would have dropped the engine. Would have made every single task much simpler and would also allow you to inspect or replace every hose in the AOS system, which I could not do working just from the (removed) transmission end. Even the little green cam plugs on the rear of the DS head are very awkward, both to remove and replace, with the exhaust system in the way. All I have done so far is move it around at my own property but hoping to get a real drive tomorrow and see if it behaves.

I don't know why everyone tries their best to avoid dropping the motor on these cars as it not so hard and makes working on them so much better once out Best to drop engine and box together I did this with a motorcycle jack under engine and trolley jack under box , it takes half a day to get out!! The engine and box are held in by eight bolts only!!!! After dropping oil and coolant Remove under trays and support bars below, and put jacks in place, unbolt clutch slave cylinder, unbolt box and slightly unbolt engine mounts, to give more room in engine bay Disconnect coolant pipes, ac pipes and power steering pipes then unplug the two wiring loom connectors and drop it down That's it takes half a day probably less once you have done it a few times Then working on the engine is a pleasure instead of a pain in the ****!!

How do we trick Noz1974 into revealing his true identity as KrazyK?

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I'm betting there are at least a few here that would suggest KK not give you any advice on this...

I think the advice to drop the engine is proper, regardless of the source. I was trying too hard to avoid dumping the coolant. And if I had known at the beginning I was going to replace the AOS, and how awkward it is to work on from the transmission end, it would have been a more obvious right choice. I could really tear this job up if I were to do it again, but I hope I don't need to!