Problem with water vapering fast.

[ChevyRay07]

I have 1985 Chevy Scottsdale rebuilt a 350 motor of a 79 suburban double time chain. I just notice that theres thick white smoke coming out the exhaust and is to much of it when the motor is warmed up already it still has some coming out of it and I was wondering if it's my head that are bad or the gaskets are maybe broken and they also told me that the heads got hot but still were good. So I'm wondering is it the gaskets or the heads or maybe the carburetor that's causing that because it's never been changed.

[winky]

white smoke usually means coolant is getting burnt... there are a few ways coolant can get into the combustion chamber. cracked head, warped head/ block, bad head gasket, cracked block, possibly the intake (i doubt) i dont think your carb is the problem. who told you the heads got hot but were still good? a machine shop? or the previous owner?

[ChevyRay07]

The machine shop told me the heads were good. It done it before cause they didn't seal it right so they took the heads out and took it to the machine shop and checked them and were say they were good so they reseal them and it stopped smoking like that anymore and then I changed the thermostat because the hose will get hard and blow up like a balloon so I'm think that the heads got hot again?

[bd]

Remove all the spark plugs - keep them in order by cylinder number.  Check the electrodes and insulators to see if any are wet with coolant.  Unplug the 12-volt ignition power lead from the distributor.  Use a radiator pressure tester to pressurize the radiator for about 15 - 20 minutes.  Then while watching the engine, have an assistant crank the engine a couple of revolutions to see if water sprays out through a spark plug hole.  Try to determine which cylinder.  You may have to repeat the process a couple of times.  In addition, run a compression check and write down the readings.  The idea is to determine whether the problem is restricted to within the cylinder, or leaking internally from another location and finding its way into the cylinder(s).

What transmission are you using?

[ChevyRay07]

I have a 700r4 in it.

[mike357]

Has the motor ever ran without smoking? The reason I ask is: I just stuck a rebuilt motor in my '77. It blew smoke as well. I was getting coolant in #5. I just figured the head was cracked. But when I started to remove the head I realized the head wasn't torqued.

[Stewart G Griffin]

Do you have dual exhaust?

First thing to check is unplug the vacuum modulator at the modulator  and see if  the smoking stops.

[bd]

Do you have dual exhaust?

First thing to check is unplug the vacuum modulator at the modulator  and see if  the smoking stops.

Stewart, the 700R4 doesn't have a vacuum modulator.

I haven't pursued this thread, because the OP hasn't responded.