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Smokey Situation

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Hey All - Sorry for the long post, but this one has me puzzled and I don't know how worried I should be.

I've had my 96 Deville for about two months now without a problem, bought it with 57k. Took it on a 2000 mile weekend trip without a hitch. Yesterday I was out running some errands around town and stopped at the ATM to deposit some checks. I idled for probably 4 minutes or so filling out the deposit envolope. As I was leaving I happened to glance in the mirror to see a huge plume of smoke behind me. At first I wasn't sure if it was steam, smoke, or even the Caddy for that matter!

I immediately parked (hadn't got out of the parking lot yet) and sure enough I was blowin smoke out the pipes. Checked under the hood, couldn't hear anything strange, and naturally didn't see anything unusual. I killed the engine for fear of a ring or valve seal problem to minimize damage. Checking the oil, it was low, not even on the dipstick. Changed it 2500 miles ago with Mobil 1 (not synth) and hadn't checked it since. Added oil and I was a full 2 quarts low. Reluctantly started it again, had a bit of smoke, probably just residual in the exhaust and things were fairly clean, but still a little coming out. I babied it getting home, another 30 miles, and it seemed to clean right up after the first few miles.

Today I took it out for 50 miles, getting into things as best as traffic (and the wife) would allow and all seems ok.

I know the Northstar sips oil (well some of them it seems) and I don't have a problem with that, but any ideas on the smoke??? I didn't pay too much attention to notice if it was blue, or even if it smelled like oil, and the wind was blowing pretty good anyway even if I was paying attention. I haven't given it a good run since vacation (a Caddy at 112 is a wonderful thing), but I wouldn't expect the smoke to be that bad pulling out of a bank!!!!!! Any suggestions on things to look for or check? Thanks!

Caddies for ever!

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Well, it SOUNDS like it might be oil smoke, but some more diagnosis is certainly necessary. If the coolant is still full, you can probably figure the head gaskets are fine and rule those out. Do a compression test on all the cylinders to see if you can find anything (leaking rings, or valves/seals, etc). If you ever see it again, note the color and smell if you can.

And as bbobynski would recommend, take the car out for some aggressive driving. Get out on an empty road and put the gear selector in 2nd. Run the car way up to near redline and let off the accelerator. Let the car coast back down to 30 or 40 mph and go full throttle again, back up to near redline and then coast back down. You'll likely see a LOT of smoke out the back, but that will clean and help exercise the piston rings and possibly unstick one that might be sticking.

Older modular Ford V-8s had the exact problem you're having. No smoke at startup, but HUGE plumes of it if you let it idle and then take off, like in traffic, at the ATM, or in a drive-thru. The problem was commonly valve seals gone bad. I haven't heard of any Northstar with bad valve seals, but the symptoms here are exactly the same as those with the modular Fords.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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I idled for probably 4 minutes or so filling out the deposit envolope. As I was leaving I happened to glance in the mirror to see a huge plume of smoke behind me.

First thing I would check is the fuel pressure regulator. Remove the engine beauty cover, pull off the vacuum hose, cycle the ignition on for a few seconds (to run the fuel pump), then look for signs of liquid fuel. I was following a mid-'90s SLS the other day that put on a noticeable smoke show after idling for 1-2 minutes while stopped at a traffic signal!


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Thanks for the suggestions guys. I'll be able to give it a good run this week on the back roads to work. Gotta watch for Rosco though... The car came from one owner in Fl on a corp lease, so I don't imagine it was hot rodded to often. I on the other will take care of that B). I'll check the pressure regulator and see what's up there. It has only done it once thus far (that I've noticed anyway), so maybe its just a sticky ring. Let's hope anyway!

Thanks again!

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