1992 f250 351 motor 4 x 4 111,000 miles

Ok so recently I noticed the temp gage slowly creep up to 3 hot this is too hot for normal but it would not over heat. It would go down to 1 hot and then back up slowly. About that same time the heater stopped working in the cab.

I thought thermostat so I changed it. Now the motor will not get hot the gage barely moves.

I have tried a few things after reading boards, ralking to friends and talking to the guy at the parts store.

I changed the blendor switch motorcraft part number yh-530. Did this thinking posible vacume problem for heat in the cab. This did not bring the heat back.

I flushed the coolant system with an at home kit. Everything in there was very dirty no chunks though seamed like no plugs. Also took the garden hose off to see how the water pump was pumping, this was on the heater hose, and it seamed to be pumping enough.

I put a piece cardboard in front of the radiator this did get the motor hot above 1/2 hot on the gage bit the heater in the cab did not get hot still.

I don't know what to do from here Please help.

 

It sounds like your new thermostat is defective, what brand was it? Only a genuine Ford thermostat is recommended. After you get the thermostat squared away, if the heater still doesn't work good you would need to flush just the heater core or if that doesn't help replace the heater core.

 

Are stant stats good?

 

I always go OEM on thermostats and radiator caps.

 

Did you burp it? If you just bolt it all together, fill it and put the lid on, you very well could have trapped air. I always run the engine with the cap off until the stat opens and the coolant circulates a little, fill it and close it up.

 

Good plan.

 

Don't be afraid to flush the system again. After 20-some years, lots of sediment, rust, stop-leak, etc. can build up in the system. I had a similar no-heat situation in my truck, a second flushing was required to get heat in the cab like it should.