My car blew a head gasket in the fall. A friend replaced it and rebuilt the head. The head was taken to a machine shop, was not warped but was planed just a little. The engine was put back together but it continues to gunk up the radiator with yellow gunk. We put block sealer in and it today there is gunk in the over flow bottle again. This is a 1998 Honda Accord with only 103,000 miles on it when the gasket blew. Any ideas?
Is it a browny goop? You could do a pressure test on the cooling system and a compression test on the cylinders. Both of these together will tell first if the cooling system has a leak and secondly if head gasket was done right. If the head bolts were not new and the head bolts were not torqued in the proper sequence and proper foot pounds, you could still have a head leak.
If it’s an automatic, the oil (if it is oil) could be coming from the transmission which has a cooler built into to radiator…
The next step might be cleaning the cooling system with a powerful cleaner and removing the overflow tank and cleaning it out too…