1989 Suburban smoking has me stumped

[cuer]

I drive a 1989 GMC Suburban 7.4L 2WD with towing package. In the last month it has started smoking only after it is warmed up and I have come to a complete stop at a stop sign or a traffic light, when I accelerate I get one large cloud of white smoke. It does not smoke when I'm idling or when I'm driving.

In the past month I have replaced the transmission pan gasket, the PCV valve, the oil sending unit, the transmission to radiator lines, plugs and wires, valve cover gasket, the oxygen sensor, the oil cooler lines and the clutch fan motor. The cylinders were checked for compression, they all have at least 150 lbs. I also changed the oil and filter and added a quart of Lucas Engine Oil Stabilizer.

All the above work has solved my oil leak and transmission fluid leak, but I'm still smoking. Perhaps wise minds could point me in the right direction. Thanks for any help.

[2000CAYukon]

White smoke is typically water/coolant in the combustion chamber. Are you loosing coolant?

Might be a good idea to get the cooling system pressure tested. Sometimes, the intake gaskets leak causing water/coolant to get into the cylinders.

//2000CAYukon

[cuer]

My coolant level is holding steady, no loss. I'll get the cooling system pressure tested, maybe that will uncover something. Thanks

[trappie]

White Smoke = coolant/water

Black smoke = fuel

Blue smoke = oil

Since it has only been doing this for a month, maybe your coolant loss is not yet noticeable. I would put money on intake gasket.

[cuer]

I had my neighborhood shade tree check the cooling system pressure and he says it looks good. I see to notice a smell when it smokes, but I almost think it smells like oil. I guess I'll replace the intake gasket anyway and see if that helps. Thanks for all the info.

[Larry Derouin]

Check to see if the smoke is actually WHITE vs. a VERY LIGHT BLUE GRAY. Leaking valve seals/guides will give this symptom and with the small amount of oil getting to the cylinders the smoke has an almost white appearance. Stick a piece of cardboard about 3" from the tailpipe at idle and goose the throttle a couple of times. If it's water you'll get clear stains and if oil.......the stains will be black and greasy.

My bet is on a couple of valve guides/seals.

Larry

[cuer]

Thanks for the tip. I'll check it out A.S.A.P.