Where does your temp gauge sit?

[Dirtyowlnumber4]

Someone put water in this trucks rad and left it for like 10 years, so im going through the motions to try and get it fixed.

 

I bought a duralast thermostat for it, because autozone is right next to my house, and it opens up when the temp gauge is about halfway. it seemed like previously it tried to open just above the second tick mark right above C, but it was pretty erratic.

 

 The water is fine on the highway or in the night but if i try to go up a hill in the daytime it boils pretty much immediately. 

 

i dont have a laser thermometer so i can’t tell how hot the coolant is when its operating normally, but if it is supposed to hang around or just below the middle normally ill start to look at other causes.

[datzenmike]

Maybe a needle width above 1/2 on the marked 'run range'. This is with a 180-185F thermostat. My 620, 720 and two 710 gauges were this way.

 

Over heating can usually be one of two categories. Not enough air flow or not enough coolant flow.

 

Lack of air flow...

1/ Rad exterior fins blocked with peeling paint, bugs, dirt or debris.

2/ Rad shroud missing. Increases fan efficiency at low speeds.

3/ Clutch fan slipping too much. Should turn freely but give it a hard spin and it should stop immediately

4/ Rad not sealed to rad support air going around or over it. Seal with foam rubber strips

 

Lack of coolant flow...

1/ Rad interior tubes crusty with hard water scale. Remove, cap on, pour jug of CLR in to dissolve scale over night.

2/ Soft lower rad hose collapses from pump suction when revved up. Watch and rev engine.

3/ Faulty thermostat. Don't waste time testing, it's out anyway, just replace. If doesn't help keep old one as spare.

4/ Leaking heater is by passed by joining the two hoses together (big no no) If joined together flow MUST be blocked!!!

 

Also ran...

Retarded timing

Faulty sender or gauge. Shoot thermostat housing with IR gun to confirm.

Low water. Get a coolant recovery tank and special rad cap.

 

Definitely flush the block and heater out. 

[Dirtyowlnumber4]

ah the heater hoses were joined together. didn’t know that was illegal

[datzenmike]

lol It's not illegal but this is hot water from the head being routed directly back into the engine without ANY cooling. If they were connected to the heater core the water is shut off when not in use. The heater hose probably flows about 1/3 of the water that would flow into the rad. This is a lot of water by passing the rad and puts a strain on the cooling system.