'93 Sierra Whitish Exhaust on Startup

[TaterTots]

Hi everyone,

I'm new to the forum and have a quick question. I have a 1993 GMC Sierra (1/2 Ton 4wd -- 350 -- 190k miles) and recently when I turn the pickup over in the morning I'm greeted by a hard idle and clear/whitish exhaust. About a week ago, the pickup was overheating, so I changed out the thermostat. Otherwise, it's been running great. Now, with the hard idle and whiteish exhaust, I'm worried that I have a blown head gasket. However, the exhaust does not smell like coolant, the oil is clean, and the white exhaust stops once the vehicle is warmed up...so...maybe it's eroded valve stem seals?

Anyone experience anything similar?

TIA--looking forward to learning from y'all.

 

[steve53]

Blue smoke is burning oil, black smoke is a fuel problem, white smoke is from burning water/anti-freeze. You have a water leak somewhere that is getting into the internal part of the motor. More than likely its the head gasket. I don't know if this will work but maybe try stop leak, for a cheap fix.

 

[98trck]

i have used bars stop leak but the high dollar ($60plus) one that has kevlar fibers in, it worked for a slow water leak that was probably intake gasket which is a common problem on the vortec motors (i had replaced gasket once before)so if you try stop leak do it right, don't buy the $10 stuff
PETE

 

[TaterTots]

Thanks for the insight!

 

[TaterTots]

Update

Finally got desperate enough to take it to a shop that I trust--and I found out that it's eroded valve stem seals...