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Old 11-21-2019, 01:09 PM   #1
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Motor is bad

So at my last event, I had the engine stall and start again. Upon driving it easily back to the pits, after a restart - it was smoking (white smoke) quite a bit. It's a 2005 3.6 motor which is an in-between the 996 and 997 (it has the large IMS that the 997 has that can't be removed without splitting the case) although it's listed as a 996.

Got it home, drained the oil and found a strong gas smell in it. Pulled the plugs and all were black but all about the same. Figured I had better pull the intake, and sure enough - ton of oil in each of the plenums as well as the throttle body. So I replaced the AOS (it has a Motorsport AOS).

After it was reassembled, I did a compression check. While all the cylinders read pretty damn high (230-245 psi) one read 95-100 on two tests - inner cylinder on the drivers side. So I put it all back together with new plugs and fired it up. Starts and runs fine and no more large amounts of white smoke - although there was a bit of white smoke from the bank with the low compression.

While I haven't done a leak down test - or checked the bore with a scope - something is obviously wrong with the one cylinder.

So - at this point I'm pretty much thinking finding a used engine. There are quite a few 997.1 3.8's out there, but not sure if they would bolt up to the trans or not. Anyone know? Also - not sure how much difference there is between them - and I would also assume the 3.8 doesn't have a dipstick etc.

Any info would be helpful.

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Old 11-21-2019, 02:23 PM   #2
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Quote:
Originally Posted by rastta View Post
So at my last event, I had the engine stall and start again. Upon driving it easily back to the pits, after a restart - it was smoking (white smoke) quite a bit. It's a 2005 3.6 motor which is an in-between the 996 and 997 (it has the large IMS that the 997 has that can't be removed without splitting the case) although it's listed as a 996.



Got it home, drained the oil and found a strong gas smell in it. Pulled the plugs and all were black but all about the same. Figured I had better pull the intake, and sure enough - ton of oil in each of the plenums as well as the throttle body. So I replaced the AOS (it has a Motorsport AOS).



After it was reassembled, I did a compression check. While all the cylinders read pretty damn high (230-245 psi) one read 95-100 on two tests - inner cylinder on the drivers side. So I put it all back together with new plugs and fired it up. Starts and runs fine and no more large amounts of white smoke - although there was a bit of white smoke from the bank with the low compression.



While I haven't done a leak down test - or checked the bore with a scope - something is obviously wrong with the one cylinder.



So - at this point I'm pretty much thinking finding a used engine. There are quite a few 997.1 3.8's out there, but not sure if they would bolt up to the trans or not. Anyone know? Also - not sure how much difference there is between them - and I would also assume the 3.8 doesn't have a dipstick etc.



Any info would be helpful.
Ummm.... sell me the one you've got?

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Old 11-21-2019, 04:33 PM   #3
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Sorry to hear of this. Wish you the best in getting her back on the track.
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Old 11-22-2019, 06:42 AM   #4
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Ummm.... sell me the one you've got?

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Well - there's a ton of stuff on the motor I'd have to keep - so essentially with most places charging a core - I'm better off keeping it and using it for that purpose. I've also not completely ruled out having it rebuilt.
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Old 11-22-2019, 07:07 AM   #5
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pretty sure the trans bolts right on. physically, you may have to revise brake booster hoses (the 3.8 probably has a tandem vacuum pump on one of the oil scavenge pumps) this is a good thing. bigger concern would be engine mgmt - don't think you want a 9x7 computer in there as they *i think* have built-in stability systems that might get confused by your car (at some point they moved to wideband o2 sensors as well iirc). better to make your current computer work, as primary impediment to swaps (variocam+) should not be an issue here. so, just a matter of getting a 3.6 computer to feed appropriate fuel to a 3.8. should work ok as-is, but an aftermarket tune would clean it up regardless (uncertain what you are running now). of course the wiring harness; assume you will have to put your 3.6 harness onto the 3.8 (could be wrong) and you may find the need for some voodoo there (changes in connector shape, etc.).
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Old 11-22-2019, 09:05 AM   #6
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Originally Posted by rastta View Post
So at my last event, I had the engine stall and start again. Upon driving it easily back to the pits, after a restart - it was smoking (white smoke) quite a bit. It's a 2005 3.6 motor which is an in-between the 996 and 997 (it has the large IMS that the 997 has that can't be removed without splitting the case) although it's listed as a 996.

Got it home, drained the oil and found a strong gas smell in it. Pulled the plugs and all were black but all about the same. Figured I had better pull the intake, and sure enough - ton of oil in each of the plenums as well as the throttle body. So I replaced the AOS (it has a Motorsport AOS).

After it was reassembled, I did a compression check. While all the cylinders read pretty damn high (230-245 psi) one read 95-100 on two tests - inner cylinder on the drivers side. So I put it all back together with new plugs and fired it up. Starts and runs fine and no more large amounts of white smoke - although there was a bit of white smoke from the bank with the low compression.

While I haven't done a leak down test - or checked the bore with a scope - something is obviously wrong with the one cylinder.

So - at this point I'm pretty much thinking finding a used engine. There are quite a few 997.1 3.8's out there, but not sure if they would bolt up to the trans or not. Anyone know? Also - not sure how much difference there is between them - and I would also assume the 3.8 doesn't have a dipstick etc.

Any info would be helpful.
What year is your car ?
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Old 11-22-2019, 09:06 AM   #7
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pretty sure the trans bolts right on. physically, you may have to revise brake booster hoses (the 3.8 probably has a tandem vacuum pump on one of the oil scavenge pumps) this is a good thing. bigger concern would be engine mgmt - don't think you want a 9x7 computer in there as they *i think* have built-in stability systems that might get confused by your car (at some point they moved to wideband o2 sensors as well iirc). better to make your current computer work, as primary impediment to swaps (variocam+) should not be an issue here. so, just a matter of getting a 3.6 computer to feed appropriate fuel to a 3.8. should work ok as-is, but an aftermarket tune would clean it up regardless (uncertain what you are running now). of course the wiring harness; assume you will have to put your 3.6 harness onto the 3.8 (could be wrong) and you may find the need for some voodoo there (changes in connector shape, etc.).
Yeah - it's running a full Motec harness - so that wouldn't be a big issue - and I have a guy to do a full tune. Issue would be coolant lines and vacuum lines like you said - also the issue with the dipstick, oil fill etc.
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Old 11-22-2019, 02:49 PM   #8
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What year is your car ?
It's a bastard :-) It's a 2000 Boxster S with a 2005 M96-03 3.6 swap running on a Motec ECU.

As I dig into this further - couple things on the M97 that would be an issue. Electronic dipstick. I don't know if you can simply add a dipstick like you can on some Audi's that have this or not. Complete deal breaker right there. The other is the Vario+ would require a complete retune. Last but not least - the Motorsport AOS I just bought wouldn't work - the M97 Motorsport AOS is like $1800.

SO - it's rebuild or buy a replacement.
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Old 12-08-2019, 07:52 AM   #9
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It's a bastard :-) It's a 2000 Boxster S with a 2005 M96-03 3.6 swap running on a Motec ECU.

As I dig into this further - couple things on the M97 that would be an issue. Electronic dipstick. I don't know if you can simply add a dipstick like you can on some Audi's that have this or not. Complete deal breaker right there. The other is the Vario+ would require a complete retune. Last but not least - the Motorsport AOS I just bought wouldn't work - the M97 Motorsport AOS is like $1800.

SO - it's rebuild or buy a replacement.

I have a 2001 engine rebuilt with all LN parts to make 3.6 liters for sale. I rebuilt my original engine in my 2000 Box S in 2010 the same way & love the difference. Especially the 273 ft.lbs of Torque
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Old 12-13-2019, 04:29 AM   #10
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I have a 2001 engine rebuilt with all LN parts to make 3.6 liters for sale. I rebuilt my original engine in my 2000 Box S in 2010 the same way & love the difference. Especially the 273 ft.lbs of Torque
Send me specifics at jlucchio at comcast dot net. Thanks!
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Old 12-13-2019, 09:17 AM   #11
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Send me specifics at jlucchio at comcast dot net. Thanks!
Here's the link to the build tread on Rennlist.com

https://rennlist.com/forums/996-forum/649044-3-6-rebuild.html
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Old 12-16-2019, 04:47 AM   #12
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Here's the link to the build tread on Rennlist.com

https://rennlist.com/forums/996-forum/649044-3-6-rebuild.html
At this point - I'll either rebuild what I have as a 3.8 or 4.0 or sell the car with the bad motor.
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Old 12-17-2019, 02:45 PM   #13
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At this point - I'll either rebuild what I have as a 3.8 or 4.0 or sell the car with the bad motor.

I have a extra set of ARP rod bolts I'm going to sell too.

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