Confusing motor problem.

I'm running an SBC and started to notice white, whispy smoke out the drivers side exhaust only. It was water/coolant smoke for sure. I had just put a new head on it, so I figured I had screwed something up or the gasket didn't seat etc. I put off fixing it because the car is my daily until it started doing a weird form of dieseling upon shut off. It would diesel but it would almost sound like a steam engine with like a "chuff, chuff" noise. Strange, violent & disconcerting to say the least.

So...I checked the oil - looked fine and no water in it. Checked the water - Radiator level was down, but no oil in it. I took it off the road and pulled the plugs. They all look pretty much the same/normal to my eye. I pulled the head expecting to find evidence of the problem that had caused this stuff. Everything looks OK. No obvious problems with the gasket and all water p***ages look as if they sealed well.

Now I'm wondering WTF? I'd like to be able to figure out what caused it BEFORE I bolt the head back on and hope for the best. It is a rebuilt head so I suppose something could be wrong with it. What might cause these problems???

Any help appreciated.

Thanks,
-r

 

Most likely, after all that checking, yer' going to find a small crack in one of the exaust ports . Most do not show up until the engine heats up, and it expands !

 

Good point, If I drove the car and shut it off before it fully warmed up it would never do the dieseling thing. In fact it didn't really start the white smoke until it warmed up either.

So basically, cracked head is your guess.

Thanks.

-r

 

The cracked head theory makes sense to me. Once that crack expands it could be the source of a hot spot that would cause the pre-ignition.