I just replaced the head gaskets on my 5.0. Now it smokes (grey smoke, not really white or blue) but only after it warms to operating temperature. I got the motor from somebody and don't know if it did this before. When I had the heads off, there appeared to be very little wear inside. there wasn't even a ridge at the top of the cylinders. I have not driven the truck at all only had it running in the driveway for a total of maybe an hour. What might be causing this smoke problem?

 

Moved to proper forum.

 

So, if I understand it correctly, this is not the engine that was in your truck before, you just replaced the head gaskets on this motor and dropped it in? What was the problem with the old motor? My thought is that it might have leaked some fluids into the exhaust that are still in there and have to finish burning out.

 

That thought did cross my mind. Also, I pickled the motor by greasing the cylinder walls while the heads were off to keep them from rusting. I thought that the grease would have burned completely off in the first few moments of combustion. The previous motor suffered from a broken crankshaft.

 

I would think that grease is long gone, but I'd go ahead and drive it, keeping a careful eye on the vital signs. See if the smoke clears up.

 

I also thought that when it gets to operating temp and there is pressure in the cooling system, there could be water getting past the head gasket and seeping into the combustion chamber. How many miles do I need to drive before it's time to retorque the heads? Is a retorque even necessary? I have heard that this is required when changing a head gasket but I'm not sure.

 

They used to say 500 miles, but these days gaskets have improved so much that most do not require retorquing at all. It's been years since I retorqued heads.

As far as the water goes, you can go to any decent radiator shop and they can very quickly check for the presence of hydrocarbons in the coolant. You could do it yourself, but the test equipment ain't cheap! Although, I seem to recall there being a litmus strip type of thing for checking that, but I don't know if it's readily available.