I have a 96 camaro rs. I just replace the heads and the gaskets because the car had overheated. I change the milky oil out and put new oil and filter. I also put new plug and wires. I put everthing back together with new gaskets and now the car is running rough or mis fire. All coils are new. After putting water in the engine and letting it run rough nothing happen. When I push the gas it clears up but it mis when its idling. I check my oil afterwards and it was milky again. What could be the problem? Could it be a crack block?

 

Did you have the heads tested before putting them back?

 

Yes they are used but in good condition

 

By tested, I mean pressure tested for cracks ,and resurfaced so that they are straight and seal properly.

 

Overheating an engine can result in a possible warped head(s), cracked head(s), or cracked block. Everything should have been gone over with a fine tooth comb.

 

They were rebuilt

 

Was water missing from the radiator after you filled it and run the engine? If so, you could have cracked block or intake/head gasket leak. Are you sure you got them torqued down properly? White smoke coming out the exhaust?

My son overheated his and when we had the heads test, one was cracked.

 

Did you use new head bolts...I hope?

 

New bolts are required on the heads, though I usually suggest moving to arp head studs just to be safe. Same price, and re-usable.

 

I drain the oil and there was alot of oil and water mixture. It was draining for a least 15 min to 20 min. Could this be a sign of a cracked block. I did put new head bolts.