martsink

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!

Atrox

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.

TempleCloud

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 ?

AWDGuy

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.

martsink

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?

FRUNKenstein

extanker

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

martsink

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.

FRUNKenstein

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.

Ahsai

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.

Woodruffian

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.

martsink

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.

Ahsai

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

martsink

Thanks, I appreciate it.

Macster

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.