Overheating problems

225,000 miles on 92 vehicle. Water pump was leaking so hubby after many cuss-words, put in the new water pump. Drove it Monday, Wednesday, Thursday, Friday & Saturday. Sat. started blowing cold air but gauge was fine. Took to store, gauge would so up and blow cold air then down and blow hot. Stopped and got thermostat. Started running hot. Put new thermostat in. Drove to work Monday. Started blowing hot and cold air. On way home, overheated. Pulled over, put water in and made it to gas station. Filled up radiator and headed 6 miles home. Started going to red, then dropped down to middle of gauge. Blew cold air though. Made it home before it was just above half way on gauge.

There may be air trapped in the cooling system.

To remove any air from the cooling system try this. Get the engine up to operating temperature. With the engine idling, slightly loosen the upper radiator hose clamp. Take a small flat bladed screwdriver and slip this between the upper radiator hose and the radiator hose neck. Allow the engine to idle until all theat comes out of the upper radiator hose is coolant. Remove the screwdriver and retighten the hose clamp.


You clearly still have a leak. And air in the system.

At this point the best thing would be a system pressure test. Find and fix the leak(s), refill and air purge the system, and test it out thoroughly. At this point the radiator may be crudded up with residue, the fans clutch bad (I think the 4-Runner has a mechanical fan, could be wrong), who knows what. It needs a good going over.

Since it’s been repeatedly overheated, you may want to run a pressure leakdown test on the cylinders as well. Might as well get it all fixed properly.

If Testers idea has been checked and there is still trouble then…
It has been my experience that when a problem is fixed and more problems arise directly after and relating to the original problem then something went wrong with the original repair. This may include a faulty part, or (no offense to anyone because I’ve had several “learning experiences” as well) an improperly done repair.