Gray Smoke

[jerry52]

I have a 1989 GMC C1500 with 5.0L(305 cu.in) engine. When I first start the engine there's a puff of gray smoke. It smokes for maybe five minutes after startup and then stops. I am using a quart of oil for every 500-800 miles. There's 122,000 miles on engine and it sounds and works excellent. I thought it was the valve guide seals but the mechanic seems to think it could be the throttle body gummed up and maybe the valves. He said the 1989's where famous for this and it could cause the engine to use oil. He said replacing the seals would cost about $300. Anyone agree and think it might be a slug problem...which would be the cheaper route.

[westex39]

Sounds like valve guide seals to me. You may also have some valve guide wear with that amount of mileage. What usually happens when you shut off your engine is the oil will seep down the valve stems, especially the intake valve. When you start the engine the fuel will pick up this oil and burn it causing the smoke you are seeing. I think it maybe leaking quite a bit since it is doing it for 5 minutes. Normally it's just a puff as soon as the engine fires. One other way you can check this out is to get up to speed and let off the gas for a short time and then step back on the gas. If you get the smoke under these conditions it's most likely valve seals or guides.

 

Hope this helps

 

westex

[frdfandc]

Its the valve seals. My 91 escort used to do that until I replaced the valve seals. After that, no more smoke.

[Shaners]

I agree that it is most likely the valve guide seals.