3000GT....smokes at idle

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Hello everyone!

Here goes....

I have a 94 Mitsubishi 3000GT that started smoking after I had the oil changed. When it was changed, they put in 5W30 oil. It started to smoke pretty bad. I complained that I wanted 10W30 like the manual says. They changed it back to 10W30, now it only smokes after the engine has warmed up and is idling. It will not smoke as long as the RPM's are up on the car, like when accelerating or when I first start it up. It's wierd. It's a whitesh smoke, which is usually a hint of coolant, but the car never gets hot, and no coolant or water is in the oil, or has any been consumed. It uses no oil either. Just the smoke. When it is idling, the RPM's drop to about 750, and the oil pressure drops very low on the gauge. I accelerate, the car blows out some smoke. After the rpm's and oil pressure have built back up, the smoke clears. The car does not knock or ping, it actually runs great. Purrs like a kitten.

Anyone have any ideas?

posted by  steel609

Does anyone have any ideas?

posted by  steel609

It happens all the time, only after the engine has warmed up, and only when it is idling.

No signs of water in the oil at all.

posted by  steel609

also to add...

uses no coolant or oil. Both are completely full. Oil light has never came on.

posted by  steel609

Did anyone ever figure an answer to this one? I'm having a similar problem :banghead:

I just changed oil and spark plugs in a '98 Honda Accord LX L4, automatic shift....

I didn't notice the smoking right after the oil change, although, it was at night. Also, I mixed a little bit of 5W30 and 10W30, it was mostly 5W30 that went in, though. I just needed an empty can to put the used oil and didn't want to waste the remaining 10W... Honda recommends 5W30 on the Engine oil cap.

After changing the spark plugs today was when the smoking was really horrible. It starts just from the exhaust pipe, white but a lot of it, like it becomes a small floating cloud after a while. Then it seems like it starts coming from underneath the engine and everything.

The old spark plugs were drenched in oil, because about 7 qts of oil had been previously forced into the engine. Where do you think the oil came from, above, from the spark plug boots, or beneath, from the cylinders? I always thought it was from the cylinders, but I don't know if the smoking is resulting now because some oil got into them. In which case I'm totally puzzled. How can it react so badly when it was soaking in oil before?

Does anyone have any suggestions? Thanks.

posted by  JaneiR36

Coolant was also slightly beneath the minimum in the reservoir but I topped it off today.

Some mountain Dew may have also gotten into the oil. It was an empty bottle, but I did put some oil into it and then into the engine because I needed an empty bottle to store some clean oil :oops: If this is the cause, how long can I expect the engine to keep smoking?

posted by  JaneiR36

White smoke out the exhaust... oil drenched plugs... sounds like classic head gasket failure. I've had the same deal happen to me.

posted by  DodgeRida67

BTW I just wanted to say, when you have white smoke out your exhaust you are burning coolant. When this happens, do not run your engine until it is fixed. If you do, the chance is great that after doing so a major rebuild will be in order.

posted by  DodgeRida67

Turbo leak?

posted by  E36DJ

Thanks, I appreciate the info. We should have someone come look at it shortly.

posted by  JaneiR36

More than likely your valve stem seals are leaking oil straight into the exhaust bowl that then migrates to the manifold. If you have a turbo then your seal is probably knackered.

The blue smoke you expect with oil burning is only the stuff that's burnt with fuel in the combustion chamber, otherwise it will be a lovely billowing white cloud that covers the neighbourhood if the leak is big enough (e.g. a turbo seal gone kaput).

Believe it or not getting the alignment of the planets correct for white smoke production due to coolant leaking into the combustion chamber is a pretty mean feat, especially at idle. Chances are the rings and bigends will give out sooner from the acid and you will have a lovely oil smell in the cabin, than any white smoke.

posted by  Wally

Is there an easy way to visually check out any of this stuff? My manual's not telling me much (or maybe I just don't know where to look).

Wally, it is a.... lovely billowing white cloud! It just kept on going and wouldn't stop, I had to shut off the engine.

posted by  JaneiR36

Do you have a turbo? If so you need to lock the impeller so it can't move and remove the oil line bango to the turbo and use a set screw, copper washers and steel washer under a nut to seal the oil flow. Start engine and if smoke clears you know it's your turbine seal.

The leaking valve stem seals will probably show up on a vacuum gauge as a rapid flutter over 4"ish Hg as you gradually increase the revs (this can also be caused by gasket leaks, burnt valves, ignition misfire and weak valve springs, but the smoke would be a strong indicator of valve stem/seal wear).

You'll get me into trouble having me post technical stuff on this board. :laughing:

posted by  Wally

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