Just replaced the head gasket on a 92 3 litre. Gasket was obviously bad, had it shaved and checked at machine shop. Truck was steaming prior to replacement. Once replaced the engine started and ran great. It slowly began building up temp and after idling for about 15 minutes temp gauge began to reach the red. Evidence of lots of stop leak had been in the truck prior to replacing gaskets. Replaced thermostat, no change. Fan is running but seems to running slower than it should. Would appreciate any ideas on what to look for next. Thanks

 

Remove the radiator and have it boiled out by a pro. It may just be plugged.

Now I have a bucket of failed t-stats, you could have a "new" bad one. Fans are for below 30mph.

 

Also, look for the seep hole on the water pump and see if it's leaking fluid. This would mean the inner seal is bad. It may be what skypilot said, but wouldn't hurt to check it.

 

If it's had stop leak in it,the radiator is more than likely plugged and/or has enough gunk built up on the inside of the tubes hindering heat transfer,probably both.

 

cooling system needs to be burped after working on the cooling system. Best way to do this is drive the truck up on ramps, open the radiator cap (only open this is the engine is cold!) start the engine and rev it a little, add coolant as necessary. Make sure your heater is on full hot to get any air in the heater core out.