Bough a dirt cheap 996 w IMS issue, but still running. What to look for?

Hey guys, I just bought a really cheap 1999 996 with an IMS issue. According to the owner the car is still running and makes intermittent bearing noise. The mechanic did find some metal shrapnel in the oil filter. Before I go out and by a new motor, I want to tear this one apart to see if it's still salvageable. Any tips on what I should look for an where? I would like to hopefully take apart as little as possible. Alos, can you suggest any books on 3.4L rebuild? Thanks!

How much is dirt cheap? If it's the bearing replace it, why buy a new motor. Plus with the motor out you can hit up all kinds of needed repairs.

I agree with Atrox. However, unless you've got all the specialist tools this isn't going to be a simple task. I'd start by getting the 996 Service Manual and also by looking on YouTube where there's a fair bit of info re IMS. And if the car really was dirt cheap, there could also be other issues with the transmission and chassis. Why not take it to a specialist first and get their appraisal ?

if it's making noise, the bearing has likely already failed and you will need to take the entire motor apart to see what the damage the failed bearing has caused.

I got the car for under $5k. It was from a wealthy guy who just wanted it gone after he got the bad news. I managed to talk him down from 7k.The body has 175k miles on it, but is in great sape. The tranny was replace 25k miles ago along with an engine rebuild. The brakes are all new and the interior is also in great condition. I figured this car was worth the money even if I changed my mind and just parted it out. I pulled the engine yesterday, but I'm a little hesitant to tear it down without a proper manual. Does the Bently Manual cover the engine?

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the op had another thread about him buying a boxster and doing a LS motor swap i bet if he turns these cars over they say matchbox or lego

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And you have nothing better to do than stalk my posts and talk smack.It's my money, so what do you care? I agree that I don't know many things, but this is the best way for me to learn, and this forum is a great tool to get advice from someone who knows a lot more than me.

Why not trade your bad engine for a rebuilt one from MB Motorsports? Net cost $10,000. Looks like you are plenty capable of doing the swap yourself. Even with the inevitable bits, pieces and fluids you'll want to replace, you'd be all in for about $16k for a car with a lot of trouble-free miles in its future.

Jake said before his engine assembly book is comng out in March. What AWDguy said above. If you plan to learn diassembly/assembly, that's a great opportunity. If you plan to make money out of the rebuild, it's hghly unlikely given the mileage on the chassis and the cost to properly rebuild an m96 (reads $10k+ just parts and resleeving). At 175k, the cylinders are likely ovaled badly. You need to replace at least the IMSB and the IMS, then add new rings, main/rod bearings, that's easily a few thousands already.

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I have come across this before. Why someone would do an engine rebuild on a M96 or M97 engine without updating the IMS bearing is beyond me.

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A learning opportunity is exactly what this is. I already made peace with spending ~10k on a rebuilt engine from a reputable shop when I bought this car. I don't mind spending a few dollars to learn more about these engines, and if I fail, I can always just get a replacement.

You will want to use a timing kit like this (or soemthing equivalent). It has the tools you need to hold and time the cams (don't open the cam covers before putting the engine at TDC cyl #1 and lock down the cams). The kit also has the piston wrist pin install tool for you to install the bank 2 pistons. http://www.kommentools.com/collectio...-to-b9612kplus

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Thanks, I appreciate it.

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AFAIK and this question has come up before there are no factory published details regarding rebuilding a 996 engine. That is while other car makers (at least used to) publish all the tolerance and bearing fits etc. Porsche publishes nothing. Still, some (a few) DIYer's have managed this on their own with I guess good success. There is a rumor -- I haven't paid too much attention -- about a noted 996 engine rebuilder publishing a book on 996 (and maybe 986) engine rebuilding but I do not know any more than the rumor. Whether the author will publish his knowledge regarding fits, clearances, etc., I have no idea. In the case of your new engine you have to remove it and disassemble it to clean the engine of any debris it might have acquired from the failed IMSB. I recall coming across a 996 3.6l engine in for a rebuild at a dealer -- Porsche authorized rebuilds after a while -- and the tech told me he checked for any debris on the clean side of the oil system. If any debris was found Porsche would not OK the rebuild. Since the engine in question was not a high miler (there were approx. 20K miles on the engine) the "rebuild" consisted of replacing the bad IMSB, the IMS and a couple of chain guides/railes that got damaged a bit from the loose chains. Oh and giving the engine and its internals a thorough cleaning prioer to reassembly. Back to your engine: After you determine if the engine is a suitable rebuild candidate then you have to decide what needs to be replaced due to wear. This is tricky without the specifications. There are ways but they are work-arounds and bring with it some risk of getting a critical clearance wrong. You do not have to rebuild the engine. You do not have to buy a new engine although that is an option. There was a thread awhiel back about new (factory "new") Porsche engines being available for a lot less than their normal list price but I do not recall the details. If a new engine proves to be economically out of the question you can source an engine from a salvage business and install it into the car. You can of course do some engine work before you install the engine. How much is entirely up to you and how far you want to go and how far you can go given the lack of factory info regarding rebuilding these engines. Possibly of some help would be to search out threads by a few who have posted their experiences rebuilding these engines. There is at least one guy who had a number of pics along with his narative of his rebuilding.

If I only had $5k into it, I would absolutely part it. The transmission alone would get you most the way to $5k.

There is figuratively no value in a 175k mile car, even with a 'new' engine and a 'new' trans. The car shopper out there is looking at comps with 35-120k miles, and even those are barely out of the teens in value. If you want to rebuild it for your own training, or enjoyment, or to have a fun car to drive around that's fine. The 996 market is incredibly efficient. That's why you got a hi perf car for peanuts. No engine is no life, and the cost to put a rebuilt engine in makes it close to or over the value of the whole car. These aren't rare or unusual cars, so have fun/learn doing up the engine, or part it out so others will live.

scrap the motor and drop a ls motor in it drive it for another 100k

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Haha I already got an LS boxster

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Thanks for your reply. I've been collecting as many related links as I come across. I plan to filter through them and compile a rebuild document. If I get permission from the OPs, maybe I'll start a new thread to share the info with others in my situation.

Post a picture of the IMS bearing. How bad is it? Are you sure that it is the IMS bearing that is the problem? What did/does the oil pan look like? Oil pickup have a lot od debris?

You have plenty of options especially since you have a small amount of $ invested. Sounds like a good plan to me.

sell the thing to me. for what you paid.

If you have the time, rebuild it yourself! It would be a great learning experience to work and learn on these engines..

Since you already have an LS boxster, do an EJ257 (STi) 996.

Bad news! This is all that's left of the bearing (plus 4 more *****). The inner race is still inside the engine. Based on the scratches behind the cover, it seems like someone was already digging here. I still wan't to rebuild the engine myself just as a learning experience, but do you guys think this engine is still salvageable based on the bearing damage? I'm almost certain the engine did not lose timing.

Hopefully Jake Raby will chime in. 100:1 His prognosis will be bad, but more importantly, accurate! It's not that your motor can't be rebuilt, but it will absolutely require a full tear down, ultrasonic cleaning and most likely lots of new/expensive parts and tools - not to mention some real engine building skills which are not easily attainable without prior experience. If your truly interested in learning to rebuild these engines, an investment in Jake's class may be a good value. Good Luck

Is that a double row factory bearing? Whether it's salvageable depends on what "rebuild" you target at. Everything has to come part to clean out the debris for sure. The only difference is what will be done afterwards. If you just replace the damaged components (IMSB and IMS in this case so far) and put all the old parts back together, I think the engine will most likely run but who knows for how much longer. Chances are there are tons of things you want to replace while you're in there as well (e.g., timing chains, main and rod bearings, etc.). Even with minimal rebuild, the cost will be a few thousands. OTOH, if you want to do a proper rebuild (meaning engine should last >100k miles), as long as the crankshaft and cams are not damaged, other parts can be replaced and will cost $10k+.

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As you start tearing it down you are going to find more and more damage. I can't believe it was still running Ahsai and AWDGuy have already chimed in here and are going to be you best sources of DIY knowledge. Look up their build threads and keep following them. I expect Jake will chime in from time to time as well as he has done for them. As has already been mentioned, look up Jake's classes and get into them if you can as that will be a big benefit to you (of course it does significantly raise the cost of the rebuild too). Now I guess you need to start thinking about if you want to rebuild it to stock or bump it up to a 3.8 or 4.0 Good luck and please keep us posted.

At this point, I'd take a cam cover off, and look at a cam journal and also the lobes. It's a quick indication of how badly the fouled oil has messed up the engine. If you have a borescope it would be useful to look at the condition of a cyl bore, but if not, have a look at the cams and maybe figure from there. If the cam lobes and lifter face are ruined, it's a do-over. If they don't look too bad, you might be able to get away with a oil gallery flush, and quicky 'rebuild'. Not what I'm recommending, but worth a look.

Just from your prior ls boxster swap exp and the speed in which you accessed the bearing, I'd say your more than capable to address what this engine needs. Obviously the engine was operating with this failure so a thorough flush would be wise. You got this man!

Martsink, I suggest you address this specific question : " How much does a comprehensive DIY M96 rebuild cost(parts,tools,machine shop) and what skill level is required ,and what specs./ techniques are available ? " Very few DIYers have rebuilt an M96 successfully because the answer to the question above is deficient in $,skill,tools,knowledge. Even so-called engine rebuilders can fail unless they have had lots of experience of this specific engine. If you did Jake's engine class, different story. More power to you do the rebuild w/o knowledge but please promise you will share the outcome with us in view of all the advice given. The short version is exactly what the smart guys already said - use a good used engine from a reliable source. Whatever, I hope you enjoy the project and share your progress. FYI, my cost in parts and tools was around $7500 and I have a fully equipped shop with all facilities & years of Mech.Eng . auto experience. It was way more exacting and expensive than I anticipated because I did not ask the question above on this Forum before I started work. A very technically humbling,financially foolish but fascinating project for me.YEMV -I hope :-).

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This, and you never know how much or how little damage was done or what the engine would need anyway.

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Well that's the thing. It's not really like rebuilding an american V8 or something that's more common and cheaper. It's almost to the point where it's quicker and easier, with the dollar amounts of the parts involved, to take it to someone else and pay them - or at least build a relationship with a shop where they could check over work.

Agreed. Key questions -"How will you find all the debris ? " "How will you find any c/s bearing damage?" Answer : Without a complete dismantling and hot tanking ,you won't.

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A person could get a decent idea by looking around though. But again, the problem is there isn't really a "good" "cheap" fix to these, so at that point you may as well tear into the whole deal and start replacing stuff. Totally different story if cylinders and pistons and stuff could be found cheaper than one of my paychecks. Then a person could be cheap with it, fix stuff as needed, and really learn on it. IMO

The price of a replacement c/s is eye watering, so checking 'cheap' shell bearings seems wise.

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And again, with the cost of some of the parts, would it really be worth trying to reuse bearings or shafts if they are just approaching or just out of spec? Although, if a person did have the time and money, wanted to learn, and liked working on these, there wouldn't be any harm in trying to be cheap or only fixing what needs fixing - wouldn't help resale value though.

Thanks a lot guys, I really wasn't expecting this much positive and helpful input. I think the plan for me now is to tear the engine apart and see what the damage is like. If its beyond repair, at least I can get a visual on how the engine is put together and how it operates. If its not looking too bad, I will only try to replace the parts that are damaged and hopefully get it running for a little while (at this mileage, I don't think a full rebuild is worth it). If it fails in a month, then its my loss, if it lasts, thats great! Meanwhile I will keep an eye out and do some research on purchasing a low mileage engine or possibly a fully rebuilt one from a reputable shop. I'll be sure to post updates on my progress and hopefully get you guys to chime in. For now, what special tools should I be purchasing? So far I've noted an IMS tool and timing tool set.

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Put in a cheap new IMSB, get a really big magnetic drain plug, change the oil a few gazillion times, and just run it until it dies. Then part it or sell it as a roller. Could probably turn into the best $5,000 911 ever.

Actually, even though you have an LS Boxster ... you should go LS for this car and add turbos. There is a TON of room for them behind the rear wheels.

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As much as I like that idea, I'd like to stick to the stock engine. The boxster conversion was enough for me

Hey guys, I'm still deciding whether I should crack this thing open or not. Once I get all the invoices from the owner, I will see what was done during the engine rebuild 25K miles ago. That should help me decide whether its worth it or not. So far this is my minimum cost breakdown. If they did a proper rebuild, all the regular wear items should have been replaced less thank 25k miles ago. Please let me know if I should add anything: LN IMS Bearing (forum member changed his mind and wants to sell it) $600 Head Bolts $230 IMS tool rental $100 Timing Tool $200 Head Gasket $100 Used IMS Shaft $100 Misc $200 Also, a question about the intermedia shaft. How is it supported on the opposite end? Since the bearing was completely shattered and I'm assuming there was some play in the shaft. What is the possible damage to the shaft and the other support?

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my 2 cents (and I am NOT a mechanic by any stretch of the imagination): best way to thoroughly assess/discover damage (specially COLLATERAL) is a full disassembly. Then price each damaged part you discover and then you should have the BEST ESTIMATE for parts (new, used or repair). Best of luck.

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Agreed and given the damaged IMS, you need to split the case to replace it anyway. The other side of the IMS is a plain bearing riding on the main gear pump. Do you know what kind is the broken bearing? Looks like steel ***** in the photos. It lasted only 25k miles? The reason for the previous rebuild was also the IMSB?

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To be honest, I really don't know. It is possible that the previous owner opted out of the IMS bearing replacement during the rebuild. I'm trying to get my hands on the invoice to see exactly what the rebuild entailed.

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That's possible but unlikely... unless that bearing had been replaced previously before the rebuild. Can you tell if the ***** are steel?

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I just checked with a magnet, the ***** are ferrous.

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Sounds like the stock bearing. Not sure if there are others but I know FVD has a double row sealed replacement bearing (steel *****). Curious to see what you find on the rebuild invoice.

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Here is the rebuild invoice. Looks like they did change the IMS bearing. Any idea what could be the reason for such quick failure?

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Do we know why it was "rebuilt" previously? (I thought you said in a previous post, but I don't see it in a quick scan) $7500 and that parts list is more of a refresh rather than a rebuild. If that was done because something (like the IMSB) had failed it would also suggest that the motor was not completely cleaned out. If that was the case then another failure was just a matter of time. Either Ahsai or AWDGuy have a good pic in their build thread that shows how well the debris can get hidden up in places that flushing won't get out. Eventually it becomes unstuck and has its way with your "rebuilt" motor.

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can you call UFP and ask them? I am really curious now what they did with the IMS....

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The owner said he had it rebuilt due to higher mileage, but all I have is his word.

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I'll try giving the shop a call tomorrow. Do you think this is the kind of information the shops can disclose?

I don't see why they can't tell you the kind of IMS that was used in their rebuild. who knows though...

I did the $7500 UFO rebuild and could not have been happier. I did it for a failed stock dual row IMS. Their $7500 rebuild comes with some no name after market bearing. They said at the time they never had a failure. Guess this is number 1. I had them put in the LN bearing for an extra charge. At the time I was not sure if it was a good decision. Guess it was a good call. Not sure of the timing of the split, but the two guys who ran it separated and one started 9xx motorsports so you may want to call them.

There's a decent set of clips a guy did rebuilding his boxster on YouTube if you search 986fix, engine is the same as 996, it will give you some insight into what you are facing, I've just rebuilt my 996, there's a lot to learn and as others have said its not cheap, you will spend two grand just on consumable parts like new shells , stretch bolts , gasket set , rings !! Rings are expensive!! Valve guides , new ims don't forget, then tools , don't want to put you off just know it's a commitment !!

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Thanks for the info

Can you post some better and more close up pictures of the IMS bearing? If it was an aftermarket unit, there should be a spacer to make up the difference between the stock bearing width and the aftermarket unit. Take it all apart and have a good look how the engine looks like on the inside, then make a decision what to do. There are a few of us here that either rebuilt them or did extensive repairs to them. I have mine half way done and in the process off re assembling it...has been sitting idle while I finish another project.

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And the shop's word for that matter...That invoice is for all intents and purposes useless/meaningless!!! No parts prices, no labor prices nothing...There is no way in hell I would ever pay on an invoice like that...

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Meh, I paid one like that for all the work I had done this summer. He wrote out the details and itemizations in the estimate, but we negotiated a significantly lower price. My final invoice was a bit more detailed than that one, but not much.

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I spent about $2500 on bolts alone. Wish I was kidding. Got another $500 or so to purchase also....

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Argh.....It just happens to be one of my pet peeves. In my business dealings when I get that type of estimate, they don't even get a call back unless I'm in a particularly surly mood...needless to say it's not a "friendly call". If they seemed decent/hard working/good people, I usually try to make it "a learning moment" I would NEVER present a potential client/customer with that sort of written "estimate" no less an "Invoice". It's really an insult.

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As I said the details were in the original estimates. They were only off the final invoice. Given that I am sure of the quality of the work and parts for the difference of a bit over $10k vs almost $14k he could have written "did work" on the invoice and I would have been happy I can show a prospective buyer the estimate and the final invoice together, of course the obvious question would then be "where is the 'missing' ~$3500?". Some of it was the difference of the estimate quoting each job independently rather than packaging it and some of it was the owner being a good guy and cutting me some slack given the size of the whole job.

Further to Ahsai & AWDGuy: All 99's have double row steel bearings which supposedly seldom fail (ex. due to lube problem?). Its twice as unlikely that a replacement OEM double row bearing would fail after a (proper) rebuild. There's too much fishy here. The cost of the car plus a proper engine is still less than current retail. Go for it.

Does anyone know what the difference is between these two intermediate shaft part numbers is: 99610501563 99610590100

0.99999911116880332586243759236599

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Mfg Part # 99610590100 Brand Genuine Porsche Previous Revisions 99610501557 99610501558 99610501559 99610501563

I finally had the time yesterday to finish up the engine tear down. Everything seems to look really good. I did not find any damage or scratches. The current IMS shaft is welded, though it doesn't look right (see pic below). I'm not really sure at this point whether I should keep this shaft or purchase another used one from a wrecked car. Are they known to bend if the bearing fails? Whats the best way to clean up the oil passages in the block? Is this something that can possibly be done at home, or should I got to a shop? Can anyone recommend a place in the Bay Area?

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The IMS should be replaced if the IMSB failed. They extra slop will destroy the IMS. You may want to check with LNE for a rebuilt IMS and IMSB options.

"Whats the best way to clean up the oil passages in the block? Is this something that can possibly be done at home, or should I got to a shop?" Ultrasonic cleaning is recommended - I think it's actually the only way to loosen and remove potential metal particles in small/tight oil passages/corners etc. Unless you've got an ultrasonic cleaner with a tank large enough for your engine components, it's a job for a "pro shop". Search the web, I'm sure they're out there. Good Luck

Hey guys, I've been pretty busy the last couple of weeks, but I'm ready to begin working on the engine again. I plan to take the blocks and heads for ultrasonic cleaning and resurfacing. Does anyone have clearance specs for this engine? Anything would help. Is there enough clearance between the combustion chamber and piston at TDC to have the block resurfaced?

I rebuilt my M96 some time ago. I was humbled by how difficult and exacting it is. I am familiar with rebuilding 'normal' engines and machinery ,have all the tools ,equipment ,skills,experience and facilities. None of that was adequate. I spent (frugally) well over $7000(maybe more?) on parts , better equipment and specialized tools and Machine shop work. And I still had missing data on specs ,clearances and tolerances and techniques. I was fortunate to have one of the most experienced and capable Machinists to help me. The math just doesn't pencil out compared to buying a good used engine. But it was very interesting - and humbling. Until Jake publishes a book on rebuilding the M96 ,it seems like a fools errand. But it was really interesting !

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Yeah, I can definitely see it now that I have the engine apart. I think I used the wrong terms in my previous posts, I'm looking more to repair the worn parts, rather than do a full rebuild. I really don't have the required knowledge, experience, or money at this point to blueprint the engine. Maybe one day in the future...