My DIY IMS Bearing Upgrade and AOS Replacement

I bought a 2000 996 Cab this summer with 65k miles on it well aware of the IMS issue. I planned all along to do the LN Engineering upgrade over the winter and the time has now come to do it. I'll post as much detail as I can as I go along and I welcome and encourage everyone's support, advise and assistance. I am planning to replace the AOS at the same time and will look at the wear pads, chains and chain tensioners as I go along. I replaced the water pump a few weeks ago. I believe in proactively addressing weak points with any car I have. For example, I recently sold a 2001 Jag XJR that I replaced the secondary chain tensioners on. Like the M96, the 4.0 liter supercharged V-8 Jag engine suffered a potentially fatal flaw. The original secondary chain tensioners had a plastic body that was prone to cracking and loss of tension resulting in catastrophic failure. Jag refused to replace them except when the engine failed and then only under warranty. Owner outrage, talk of class action lawsuits, etc. Same as the M96. I found that both of my secondary chain tensioners were badly cracked at 60k miles and would have failed eventually. Jag upgraded the secondary chain tensioners 3 times during the production of this series. The final chain tensioner body that I installed was metal. (If you think Porsche parts are expensive, price out some OEM Jag parts!) I love my 996 and look forward to many happy years with it. Again, everyone who has done the IMS upgrade themselves, please jump in. I'd really appreciate any help you can offer.

hey pter - there's one very well done DIY post on this board by shark attack. Lot's of pictures included and he made his own tools. Last year we did a Porsche Club tech session over at SCAN where the IMS bearing was replaced, too bad you missed it, that would have been helpful I would think. Getting the transmission out is the hard part. The bearing replacement is relatively simple in comparison. Good luck, I'm sure there's a club member or two out here that would like to come and have a look/lend a hand if your interested. Me being one.

Sounds like you're doing an engine out job. Good stuff.

I've just done IMS & AOS as well and documented the job/notes/tips/trivia at this link. http://www.oz951.com/public/enginedrop.htm Good luck.

Thanks OZ951 for the link!!

I have a link in my sig as well for IMS.

Quotes source posts: 8143485, 8143503

The first thread I saw on this was Kyle's and he is an inspiration for this job. Many thanks to him for his excellent documentation. I was hoping to do the AOS from the bottom with the tranny off. Anybody done this?

Quotes source post: 8145105

lots of people - Almet is a good source of info, that is the way he prefers to do them IIRC -

Quotes source post: 8145105

Yes it can be done but it's pretty hard on a Mk1...you said you're going to look at wear pads and chains so I thought you're going to pull the engine.

Pic 1. First thing. Get the car in the air. I was dubious about doing a bunch of work and relying on jack stands alone. I just wasn't comfortable with it and I wanted more room to work. So I built up some wheel stands to get the car in the air. I'll put the back on jack stands with the wheel stands as back-up. Pic 2. Since I had to wait for my jack stands to show up, I skipped unbolting the transaxles for now and got on with the other items. Unhooked the linkage. Pliers to squeeze clips and remove linkage from brackets. Two flat head screw drivers to pry linkage from ball sockets. Pretty easy. Pic 3. Removed the clutch slave. It was a pain, but not too bad. I found a 13 mm wrench worked best to get the lower bolt started. Long extensions and swivel and lots of patience. Pic 4. Drained the tranny fluid and the engine oil. During my first oil change 3000 miles ago I installed a magnetic drain plug on the oil pan. This was my first look at it. It had a light coating of fine metal powder on it. No shavings, just a very fine powder. Any thoughts? I then loosened the transmission bolts and brackets and got ready to drop the tranny when the jack stands show up. They showed up late tonight (borrowed from a friend) but I had a commitment to do some charity work so that was it for today.

Quotes source post: 8145192

I will look at the upper pads by pulling off the cam covers and call it from there. If she has to come out, she will come out.

Upper pads don't tell the true story. At least in my case.

Whew! Getting the engine and tranny separated was lot more work than I expected. Based on the shallow depth of the IMS flange, it looks like I have a double row bearing. The RMS is not leaking but the IMS flange is. The RMS and clutch were replaced by the previous owner earlier this year and look good. (Too bad they didn't do the IMS upgrade) I'll post more pics tomorrow. Thanks to everyone for their help! Much appreciated!

Nice work. Did you lower the front of the engine by that one inch to gain better access to the top bolt on the transaxle? I see a bit of oil there under the IMS flange. Assume that's a leaking flange seal? More pics !!! kinda just kidding though...I know how hard it is when you're in the middle of the job to just stop and photograph...especially with oily hands and all. In fact any pics and documentation is well appreciated

@oz951, You did all that in this weather with the UK at a stand still. Well done m8.

Quotes source post: 8148613

Cheers, yeah, I've adjusted to the concept of sub zero wrenching now. To be honest I think I like the fact that it's too cold to rain and since the conditions haven't been great for driving on the weekends it hasn't been so bad getting these improvements done on the car. Looking forward to the first drive though, it's going to be like a new car!

Quotes source post: 8149418

Sweet page(s) OZ! Well done.

Here are some more pics. Pic #1 My stand set-up. The engine and rear are supported by jack stands with the wheel stands underneath for additional safety. The front is still on the wheel stands. It ends up with the car about 28" off the ground and level. I had to put the Harbor Freight transmission jack on top of a row of 4x4s to reach the tranny, but was able to roll the tranny out on the stand after lifting it off of the 4x4's. Pic #2 The tranny bolt organizer. They are all different and this keeps them in order. The extraction kit has arrived but I was only able to order the retrofit bearing today so it will be several days before I get to pull the bearing and replace it. I also ordered all the bolts, filters, tranny fluid etc. I will need plus a new AOS and AOS boot. The AOS is sitting right there in front of me so I'll be tackling that next.

wow is that clean. I dont like that drain blug goop at all. That actually scares me a bit. Reminds me of the oil in my 928 when i had thrust bearing failure (TBF). I think you are doing this in the nick of time.

Good Job, That stack of wood under each wheel is crazy...

Quotes source post: 8149739

I blame it on all the Behavior Based Safety Training at work. They would be so proud!

Be careful when you put the slave back in, make sure it's exactly aligned on the fork and you can install it before you lift the transaxle back into position.

Quotes source post: 8150005

Amen to that

Quotes source post: 8150005

I've been trying to decide whether to put the slave on the tranny prior to installation and do a clutch bleed after or install it once the tranny is back on. I don't have a motive bleeder but I will need one eventually anyway to flush my brake lines out. That was going to be one of my next projects.

After reading about Rodgers experience I triple checked the slave cylinder rod was properly seated in the arm - ie even though it can be a bitch to get it bolted in place I did so then undid it and checked that the rod had the optimoly lube on the end (which was picked up from the fresh blob of lube I had applied to the throw out arm - and it did) so I went ahead and re-seated it again knowing it was seated correctly.

Quotes source post: 8150225

put the tranny on the jack. Get it back under the car. get it almost up into place. Leave room to put the slave back on... then complete tranny install... no need to un hose it....

Quotes source post: 8150454

Yeah, that sounds like a great plan. Thanks!

Alright, AOS is out. Hate those F'n clips. I don't know how you get this sucker out from the top. All my clip tabs were facing towards the front of the car. Even with the tranny off and good access it was a pain. Probably took me 2 hours, mainly fiddling with the clips and the squeeze and pull connectors. I hate squeeze and pull connectors of any kind. I always struggle. Even the MAS connection on the air box gives me grief. Anyway the AOS is out and that is last time those hose clips will get used. I also pinned the engine at TDC. Waiting for the LN bearing to show up and then out with the old and in with the new. Hopefully that will happen early next week. Pic #1 AOS in Pic #2 AOS out Pic #3 AOS Pic #4 Engine pinned at TDC. You can where the pin nestles into the engine in this pic.

Awesome write-up and pics. Thanks for sharing and I hope everything goes back together nice and easy.

Good luck with the re-installation of the AOS - re-fitting the AOS is fiddly, especially getting the part with the brown O-ring/seal inserted into the block properly (and that was with a gods eye view with the motor out of the car). You might want to use one of those small flexible inspection mirrors to look at that part to be sure the thing is seated correctly.

Nice write up. I am going to drop my engine and transmission next month and go through everything. As mine is a tip and needs an AOS, plug tubes, etc... it makes more sense to drop everything. If I had a manual, after reading your write up, I would probably just drop the transmission like you did. Nice work!

Quotes source post: 8154813

The WSM are not very helpful. Rennlisters, on-line posts and some Pelican Parts articles have been the most useful. I just ordered a copy of the 101 Project for Your Boxster in the hopes that I'll get some useful information from that too.

Excellent post, Thank you for sharing.

Quotes source post: 8154839

Yup, all the info you need will be in there (a 996-specific book will be coming out sometime in 2011). I also have articles online for the replacement of the Air-Oil Separator and the Intermediate Shaft Bearing (IMS): http://www.pelicanparts.com/techarti..._Separator.htm http://www.pelicanparts.com/techarti...ft_Bearing.htm -Wayne

Quotes source post: 8155529

Thanks Wayne. I am looking forward to receiving your Boxster book. Your technical articles are much appreciated and very helpful. Your 996 book will be most welcome by all of us!

The new AOS is installed. Cam plugs are out and the cam positions marked. The bearing is here and ready to be installed. I wasn't sure whether I needed to remove the outer seal on the LN bearing prior to installation. Some of the pictures on the LN website of the bearing installed look different from the bearing as you get it. There is a cage on the outer side of the bearing. An email to Charles at LN was quickly responded to, even though the office was closed for Christmas. Now that's service! Many thanks Charles! The bearing should be installed as received. On Sunday or Monday I'll do the bearing extraction and installation. Lots of pictures to come. Merry Christmas to all. I wish you a very happy, healthy and prosperous 2011!

You mean 2011 ?

Quotes source post: 8159206

Oops! Yes 2011! Corrected.

Here are photos of the cam plugs removed and the cam position marked.

Tensioner removal. Here is a picture of the driver's side the chain tensioner still installed and one post removal. Both tensioners appear to be in good condition.

IMS Bearing Extraction Pic#1 Old bearing in place. Pic#2 Extraction tool installed Pic#3 Oil gushing out after bearing extracted. Th oil had a burnt smell and there was a lot of it Pic#4 Old bearing with seals removed. The entire bearing was filled with oil. From what I can see so far, the engine oil was lubricating the bearing pretty well. I'll do a complete disassembly later to look for wear or corrosion.

Houston, we have a problem! I have run into a problem inserting the new dual row bearing. The bearing is stuck half way in and has shifted slightly crooked ~ 1/16". I can not get it out or get it in farther right now. Very disappointing. I had it in the freezer overnight but it was hard to get in right from the start. I am not sure what to do next and am waiting for input from LNE. I can't extract it using the extraction tool because the spindle size is larger than the old bearing. I don't dare hammer on it any harder than I already have and already fear I may have hammered too hard. Everything had been going very, very well up until this point. Maybe LNE makes an adaptor for the extraction tool that fits the new spindle. Here are two photos showing how the bearing is crooked. I made a mark on a piece of wire to show the difference from side to side.

Could use something like this? Put a double nut on the threaded stud and used a nut extractor. Just a thought. http://www.getcotools.com/sec_9_internal_extractors.htm

Hopefully LNE has seen this before and can walk you through a fix...fingers crossed for you. That was a lot of dark oil in pic #3 above. Is that a normal amount of oil with other IMS replacements?

Quotes source post: 8161331

What you see is what was left after most of it gushed out! There was a lot of oil and I had to scramble to position my bucket. By the time I was able to grab my camera most of the oil had flowed out. Based on what I saw it is conceivable that the IMS was pretty much full of oil. Yes. I hope LNE will be able to help.

HUH, Well, I would be on my way to lowes and see what I could find to mod the puller. You cant tap the one side in to straighten it back out? I can see how you got it that far in and then it all go wrong. I am afraid you pull on it you are going to stretch the carrier and also put a stress on the bearing it was simply never made to have. What did they say about the seal?

Quotes source post: 8161366

I will wait to see what Charles has to say on getting this bearing out or in properly. I have tried tapping on the one side of the bearing driver to straighten it out but no change. It just won't budge. I don't understand how it could be half in and then get crooked. Charles emailed me on Friday and he said to leave the seals in. Install it as received.

Well, Charles just replied to my email. He doesn't have an adaptor for the extraction tool that will fit the new spindle. He suggests tapping the new thread into the existing adaptor. Bother. I don't have any tapping tools.

If your bearing is half way in it cannot be that cocked. I would venture to guess it isnt that far in yet and that you may be able to tap it straight, but gently, if there is such a thing

My $0.02 is you need to pull it out and refit. tapping on the side sticking out is going to push on the opposite side. Don't hit that shaft either, you'll be putting a force on the inner race that could damage the bearing cage. Go to a nut and bolt shop (industrial) with the nut that goes on the new IMS bolt. You'll be able to find what you need there for the new tapped thread for the extraction tool. http://www.pacificfasteners.com/ <-----(Burnaby, BC) http://www.lelandindustries.com/productcatlg.asp <-----These guys might be the right guys....(Port Coquitlam, BC )

I have a solution! Tap the center spindle from the stuck bearing gently into the IMS with your plastic hammer. Insert the "easy out" tool that comes with the IMS kit through the center of the bearing. Unscrew the hex fitting from the extractor tool and screw the small inner threaded shaft into the "easy out" nut. Reinstall the extractor tool and extract the stuck bearing. It took very little effort to extract the stuck bearing. Fish out the spindle from the IMS and press back into the bearing. Bearing is back in the freezer. Next attempt to install will skip the Loctite bearing goop. That was probably the problem since it is obviously a tight fit without it.

Jeezuz that was a scare....and it isn't even my job. Is the race that the bearing fits into marred up at all? Nice fix Pat. Good luck on the next attempt.

Good that you got her out! Doublecheck the bore where the bearing installs into is clean and free of swarf/shavings from your first bearing install attempt.

Quotes source posts: 8161744, 8161748

Yeah, I was sweating. Nothing is marked up at all. Its all good. Whew. I am glad that I stopped and thought things out so that I can make a fresh attempt. I really wasn't comfortable trying to force it in. I really think the problem was the Loctite goop making the fit too tight and making it end up crooked. Fingers are crossed for the next try.

Glad to see that you got your issue sorted Pat... there's got to be a bit of drama with a big job eh

Well done, good luck on the reinstall.

Quotes source post: 8154839

Glad you got everything straightened out. (Sorry, couldn't resist!) I was on pins and needles all the way over the pass from Eastern Washington, waiting to hear that you got everything taken care of. Congrats on the fix. LOL, my car is a Tip... hence the "manual" reference. I have the WSMs... Point well taken, however. Your write up is going to be really helpful in the very near future. Keep the great photos and writeups coming. Cheers, Tom

All done! After another night in the freezer and without the bearing mounting goop, the bearing tapped in nicely. For those who end up with a stuck bearing like I did, here are a couple of photos of how to extract the stuck bearing using my old bearing as an example. After all the tapping and extracting I checked the cam positions to make sure that I hadn't moved the cams. They hadn't budged. After I installed the bearing and IMS flange fully, I reinstalled the tensioners and rotated the engine by hand several times. When back at TDC the cams were in the same position as before. Pic #1 is the extraction tool with the hex end removed to show the inner shaft and the "easy out" tool. Thread the "easy out" tool through the center of the stuck bearing. Pic #2 is the extraction tool shaft threaded into the "easy out". Now you can reassemble the extraction tool and remove the stuck bearing just like you did the original bearing. Pic #3 is the new bearing almost home. A couple more taps were required to seat it fully and expose the groove that the cir-clip fits into.

How was the original bearing? Well, the IMS shaft was full of a lot of burnt smelling oil. The smell of that oil still permeates my garage 2 days later. The bearing races, cages and ball bearings all look fine. There was no grease present in the bearing but it was chock full of oil. There are no signs of wear that I can see. It seems like the seals on bearing were allowing enough oil in to keep the bearing lubricated. Never-the-less, I did this job for peace of mind. Pic #1 Original bearing as removed inner seal Pic #2 Original bearing cages removed

After installing the bearing I put everything back together. The flywheel, clutch and pressure plate were easy. After refilling the tranny with Swepco 201 I jacked it up close to the engine and installed the clutch slave cylinder. With more room to work it went on with relative ease. Then I wrestled with the tranny for a long time getting everything lined up and getting it seated. That was a drag. After refilling the engine with oil came the moment of truth. With the car still on the stands I fired it up. Everything sounded good and the clutch and gearbox worked fine. I have taken it for a short test drive today and will be going out for a longer drive in a bit. I want to thank everyone for their support and in particular want to thank Shark Attack, Eharrison and Charles at LNE for help! This is a great forum for getting help. I hope that my posts will help someone else too.

What do the cages look like? Were they all metal?

Quotes source post: 8165890

The cages are metal and look to be in perfect condition.

Great thread, Thank you and Congratulations

Quotes source post: 8165708

Congrats on getting her back on the road again. Your write up will definitely be a help when I tackle mine. Nice work!