Bough a dirt cheap 996 w IMS issue, but still running. What to look for?
02-07-2016 | 11:23 PM
#17
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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.
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.
02-08-2016 | 12:39 AM
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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.
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.
02-08-2016 | 01:26 PM
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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.
02-08-2016 | 01:40 PM
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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 
02-08-2016 | 02:08 PM
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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+.
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+.
02-08-2016 | 02:11 PM
#29
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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.
02-08-2016 | 02:15 PM
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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.