Fixed my sweeping temperature gauge

[shane96ranger]

I recently bought a 96 Ranger from the original owner. It has 107,000 miles. When I got the truck it would never get up to temperature. I replaced the thermostat with a CST brand stat from Autozone. Then the thing would get to the normal temp, but the gauge would always sweep up to the half way point then come back down to normal temp. I would check the coolant every morning, but it was never low - so there wasn't air in the system. Then I decided to pull the stat back out and look at it. The spring had rotated in a manner that it was causing it to open crooked. So the brass part was rubbing on the housing on it's way open.

I actually put a Fail-Safe thermostat in there now made by motor-rad; also from Autozone. It works beautifully now. I also followed some advice I saw elsewhere on TRS to cut the little pellet out of the thermostat, which made it a lot easier to burp.

I just thought that may be useful info for someone that had the same problem.

 

[AllanD]

I have never removed a used thermostat from an engine and found that little
"Barbell" free to move...

I generall not only remove it but run a 1/4" drill bit through the hole.

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[shane96ranger]

I ran a drill bit through also

I only did 5/32" though.

 

[fireguy12117]

what's the purpose of getting rid of the ball and drilling the hole? i know you mentioned its easier to burp, but beyond that what does it do for the engine?

 

[shane96ranger]

The sole purpose for me was to burp it. IMHO, the 4.0 is the hardest engine I've ever burped. Over time that ball or pellet can get stuck and make it a pain to burp later on as well.

 

[AllanD]

The Shape and installation of the thermostat and Thermostat neck
trap air.

The object is to get ALL the air out of the cooling system.

a pocket of air near the thermostat results in a Guage that does not report
accurately because the temp sensor really needs to be submerged.

But a more typical reason for a fluctuatig guage is a dirty ground
somewhere in the circuit path....

Typically the ground wire between the back of the driver's side
cylinder head and the wiper motor.

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