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Blue Smoke

I just bought a 1984 944. It starts and runs well. When I was entering on to the interstate (driving it home), it started to billow blue smoke for about 30 seconds, and then stopped. Then later as I was approaching a hill at 65 mph in 5th gear, it started again. Same thing lasted for 30 seconds, it did this 2 more times by the time we got home and only on hills and only if I was trying to maintain speed. If I held my throttle steady it did not blow smoke, but I'd loose momentum. Strangely it didn't do it accelerating from traffic lights.

My wife who was following me said it was coming out of the exhaust pipe. I said don't worry nothing I can't fix, maybe the car is one of those supper secrete Jame Bond editions and the smoke screen is broken. And then she told me I had bought a POS.

Anyway, I did a visual and there is seepage around the cam tower, but when they leak the smoke is constant, and this is a billing cloud of smoke, then it stops.

Any help would be appreciated.

Revis

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Revis Rose

'84 944 NSRC
Old 11-01-2009, 04:12 AM
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it's could be oil leaks dripping on the exhaust system. look on your exhaust manifold and see if there's a discolored spot right in front of the o2 sensor bung. cam tower gasket, rear cam tower gasket, rear main seal, various other places would be the culprit.

if there's no discolored spot, and it is truely coming out of the tailpipe, then it's more likely u have oil leaking into combustion chamber. valve stem seals, piston rings, would be the more likely suspects.
Old 11-01-2009, 04:26 AM
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Yes, especially check the cork gasket on the rear cap on the cam housing. That goes bad very easily and drips straight onto the exhaust system. It could also be the bolts came loose, since they're not tightened very hard or it'll damage the gasket.

Check your throttle body and intake J-boot for oil. It may be sucking oil out of the crankcase breather due to a vacuum leak somewhere on the crankcase, like AOS seals, rear balance shaft housing plugs, oil dipstick tube seals, oil fill cap o-ring, etc. That's a fairly common syndrome with these cars due to the overengineered crankcase ventilation system, and random smoke generation is consistent with it. It's also possible the piston rings are bad and letting alot of blowby into the crankcase, which will do the same thing as a bad crankcase vacuum leak and push oil into the intake. Seems like if the rings are that bad, you would also see alot more smoke when revving high and hard, and getting a good puff when closing the throttle (the vacuum of closed throttle at high rpm will pull oil past the rings into the combustion chamber).

How much oil does it use? Valve stem seals are also a possibility, but seem to be able to pass alot of oil without showing anynoticable signs. I've seen in a performance VW book that the culprit for unusually high oil consumption with not much smoke is often valve stem seals. Mine would devour a qt./250 miles without any leaks and without much smoke, and had good compression, except a little at full tilt before I changed mine, but I never actually got to see if that fixed it...left a few things behind during the operation... Ring endgaps were a bit out of spec after teardown, though, so who knows. Start with the easy stuff.
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Old 11-01-2009, 07:30 AM
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I did a compression test and got the following. (1st. bump/total)1. 105/176; 2. 95/173; 3. 100/173; 4. 70/170

Plugs 1 and 2 are oil foiled, 3 & 4 black soot.

After I checked that stuff I checked the oil. The oil level is 3/4 inch past the full line.... humm I think I found something really wrong here. I remember being told years back not to over fill 944, I think this is why I'll do an oil change and keep you guys informed.

Revis
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Old 11-01-2009, 12:08 PM
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compression isn't out of norm.

oo if oil is past full, it prob seeps past rear main. yea after oil change, go to self powerwash bays and spray down the engine bay to get all residual outside oil off. then u can tell if the oil change really helped.
Old 11-01-2009, 05:54 PM
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Sorry to take so long getting back to you guys. Once the oil was changed, the snow started flying and since I work under the clear blue sky's of NH, nothing got done till lately.

Found wires to A/C aux air valve not connected, reconnected it
No Carbon Canister and line running to plugged, unplugged it to let it suck in air
New plugs (the correct plugs at that), cap and rotor
Oil has been changed, no new smoke

It's running good, the Mobil 1 and new filter have taken some of the lifter noise out of it. I have not been able to take it out on the road to recreate the conditions that caused the smoke issue yet.

After inspection of the rest of the car, I found rusted brake lines that had to be replaced, then the clutch slave cylinder failed. Those are fixed and as soon as I get plates on the car I will do more testing and TS.

Thanks,
Revis
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Old 02-08-2010, 11:14 AM
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P.S.

Oh yeah I forgot to mention this, there was a lot of oil in the air cleaner. The Carbon Canister is missing and the line running to it was plugged with a bolt, how would the effect the PVC system? Is it possible that oil was being sucked out of the Oil Air Separator, due to increased vacuum and could this have been the reason for oil into my air cleaner? Oil was literally dripping out of the Air Flow Meter.
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Old 02-08-2010, 11:23 AM
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there's supposed to be vacuum sucking vapors out of the Air Oil Seperator. but there's supposed to be an element inside the AOS that collects the oil vapor into oil droplets and drip down back into the oil pan. most likely this element has deterioated and straight oil vapor is being sucked into the J boot and condenses along the walls which then seep back into the air filter.

to fix this, u need to either replace the AOS and the seals, or u need to crack open the AOS (very tedious to do as the cap is plastic welded on)
Old 02-08-2010, 12:05 PM
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Wow, sounds like your car had a PO of the highest order.
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Old 02-08-2010, 12:10 PM
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Don't know about the vapor canister. I have plugged the main vacuum line to the vapor recovery regulator in the past for troubleshooting possible vacuum leak induced running quality problems, but I'm pretty sure it's completely unrelated to cankcase ventilation. The AOS hose is pretty large, but the AOS has a fairly small port in the hose nipple to regulate airflow.
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Old 02-08-2010, 12:53 PM
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@ krystar

I was affraid you'd say that, I'm not going to attemp that until the spring, by the gods I finally got the feeling back into my fingers after changing the slave cylinder in 20 degree weather. Hopefully leaving the Carbon Canister line open will releave the vacuum on the AOS, it's not effecting the opperation of the engine, i.e. it's not running like it has a vacuum leak.

@ Rasta

LOL Aye that they were!

I have owned 4 924's and 5 944's and this is the first 944 I have ever seen with cancer and I mean things like the strut housings, the steel lower control arms, and rear trailing arms covered in flaking rust, the steel brake lines eaten up with rust.

The car was bought as part of the factory Tourist Pick-up program, so at one time the owner had to have cared for it. But being that it is a Black on Black NSRC Non-Sun-Roof-Coupe, with LSD and Cruse Control Delete, Sport Package, and 7" & 8" Fuchs wheels, I think this is one that's worth saving. To get it to pass the safety inspection I need to replace the hard lines to the rear brakes and I should be steetable again. It's not a great 944 but it's okay for a car that has spent it's 26 year life in the road salt of Massachuettes and New Hampshire.

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Last edited by Warwood; 02-08-2010 at 03:06 PM..
Old 02-08-2010, 02:36 PM
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