I just purchased a very nice (almost mint) '99 QX4 with low miles (about 100k miles), but when started, it puts out moderate oil smoke until the engine is warm, and then no smoke at all.
I would have expected MORE smoke when warm as the oil is thinned out when warm.
Any ideas?
Thanks,
Bob
1999 QX4 Smokes until up to temperature
Re: 1999 QX4 Smokes until up to temperature
Well, blue smoke is oil burning. Either worn cylinders (oil ring not sealing) or worn valve seals.
Worn valve seals typically get "better" at idle, then blow blue smoke as you accelerate as the oil is sucked into the cylinders.
Maybe the mileage isn't right?
Worn valve seals typically get "better" at idle, then blow blue smoke as you accelerate as the oil is sucked into the cylinders.
Maybe the mileage isn't right?
Re: 1999 QX4 Smokes until up to temperature
I understand what you're saying, but normally "worn engine" smoking doesn't cease completely when a worn engine is up to temp.
When cold the engine produces a modest amount of smoke while driving, when warm, though, there is no way to make it smoke either by accelerating hard, or by de accelerating or even allowing the engine to just idle. Guide valve seals tend to smoke first at startup from oil having run down the stems after shut down when they are barely worn, and then as the problem progresses they will smoke under high vacuum conditions that's sucks oil past the seals. Piston rings tend to be similar with oil getting sucked past them into the combustion chamber under high vacuum conditions such as when letting off the throttle. Tally worn rings smoke all the time, typically worse when hot. I've had bad oil control rings make so much smoke you could foggy parking lot at idle.
My experience has been that with a worn engine, when the oil is hot it thins out and gets by the Rings and valve stem seals, etc, even better and smokes even more than when cold.
Sure, the odometer could be wrong, but there are usually tell tale signs of high mileage like we're on the steering wheel or leather cover, the pedals, the seats, and other give-away items. This car looks like a 50000 mile car and not even a 100000 mile car. I have owned about a hundred and fifty cars in my lifetime, and you can get pretty good at guessing mileage by just being around and in the car. Of course despite the cosmetics, you can always find an engine that has been run out of oil, or on the wrong oil, or just had some cracked Rings or bad parts.
Could I have been fooled? Of course. But the point is the smoking doesn't really fit with a traditional worn engine. I was wondering if a PCV problem or a oil separator could be allowing oil to get sucked into the engine and burned rather than worn hard parts. Many engines have common failure points, and I was wondering if this particular type of engine suffers from any typical "well known" problems they cause this symptom. Quite often the best place to learn about such idiosyncrasies is on a forum where people owning the same kind of vehicle gather and share information.
I wasnt sure if these particular engines are prone to any such problems.
When cold the engine produces a modest amount of smoke while driving, when warm, though, there is no way to make it smoke either by accelerating hard, or by de accelerating or even allowing the engine to just idle. Guide valve seals tend to smoke first at startup from oil having run down the stems after shut down when they are barely worn, and then as the problem progresses they will smoke under high vacuum conditions that's sucks oil past the seals. Piston rings tend to be similar with oil getting sucked past them into the combustion chamber under high vacuum conditions such as when letting off the throttle. Tally worn rings smoke all the time, typically worse when hot. I've had bad oil control rings make so much smoke you could foggy parking lot at idle.
My experience has been that with a worn engine, when the oil is hot it thins out and gets by the Rings and valve stem seals, etc, even better and smokes even more than when cold.
Sure, the odometer could be wrong, but there are usually tell tale signs of high mileage like we're on the steering wheel or leather cover, the pedals, the seats, and other give-away items. This car looks like a 50000 mile car and not even a 100000 mile car. I have owned about a hundred and fifty cars in my lifetime, and you can get pretty good at guessing mileage by just being around and in the car. Of course despite the cosmetics, you can always find an engine that has been run out of oil, or on the wrong oil, or just had some cracked Rings or bad parts.
Could I have been fooled? Of course. But the point is the smoking doesn't really fit with a traditional worn engine. I was wondering if a PCV problem or a oil separator could be allowing oil to get sucked into the engine and burned rather than worn hard parts. Many engines have common failure points, and I was wondering if this particular type of engine suffers from any typical "well known" problems they cause this symptom. Quite often the best place to learn about such idiosyncrasies is on a forum where people owning the same kind of vehicle gather and share information.
I wasnt sure if these particular engines are prone to any such problems.
Re: 1999 QX4 Smokes until up to temperature
That's odd. If your valve guides were that worn you'd probably be seeing oil smoke upon acceleration after sitting and idling for a while. Please don't be insulted by this question, but are you certain the smoke you're seeing in the morning with a cold engine is oil smoke? I have the same model year QX with 158K and on chilly mornings I routinely get water vapor coming out of the tail pipe for around 30-60 seconds upon startup.
Re: 1999 QX4 Smokes until up to temperature
Yeah, it's oil (unfortunately).
Smells like oil, and lasts several miles.
The crankcase vent hose was oil soaked, and the PCV vale pretty sludged up, so I am trying new ones to see if maybe it was sucking oil from the valve cover when the PVC was supposed to be closed.
Time will tell I guess (when I get the new parts in).
Thanks-
Smells like oil, and lasts several miles.
The crankcase vent hose was oil soaked, and the PCV vale pretty sludged up, so I am trying new ones to see if maybe it was sucking oil from the valve cover when the PVC was supposed to be closed.
Time will tell I guess (when I get the new parts in).
Thanks-