1937 Pontiac 6 High Speed Overheating Solved

[Bob Stein]

My 1937 Pontiac had a mild heating problem when I bought it back in 2012.  It would start to overheat at speeds over 50, but did fine below that.  I tried many things over the years, from the obvious radiator check and water pump replacement to more obscure items like replacing the distributor.  As time passed, the problem only got worse, and recently it started losing coolant, something it had never done before. After the third water pump and second radiator, I discovered some oily black residue in the thermostat housing just a hundred miles after I had flushed and cleaned the system.  I decided the head gasket must be leaking - when I went to pull it, I discovered the head bolts were barely more than finger tight!  I had never thought to re-torque the head bolts after I bought the car, which had been used for tours and many long drives by the previous owners.  When I pulled the head, I found coolant  between the gasket and the block.  After having the head resurfaced, I installed a new copper sandwich head gasket and torqued it all down to 70 foot-pounds.  A test drive at 55-60 brought the car up to 195 degrees where it stayed, dropping back to 180 after I got off the interstate.  No coolant loss, no leaks.  The head gasket issue crept up on me with none of the obvious signs - no bubbles in the coolant, no coolant loss until near the end, no external seepage around the head gasket, and a not a drop of water in the oil or vice-versa.  This last was likely because of it being a flathead engine with no oil passages in the head.  Anyway, the highway speed overheating problem that has plagued the car as long as I owned it appears to be solved!

[Guest]

Nice of you to share the resolution to your problem.

Happy Touring