How to test the fan clutch?

[dremu]

having some cooling issues, namely the truck is running hot, and it occurs to me that the fan clutch may be an issue.

Background: New radiator and cap last year or two, just pressured tested the system and it held 15psi, etc.

Anyway, is there a test? Couldn't find anything in messr. Chilton, no surprise there. I have the factory books *somewhere*...

Should I just start her up and watch to see if the fan spins? Should I be able to move the fan by hand with the engine off?

-- A

 

[90_K5 Blazer]

hey dremu,

If the engine is off and the oil inside the clutch is ok, you should be able to move it by hand with a little resistance due to the oil which is normal. It should also turn when started. If not theres a major issue inside the thing

they are simple beasts to diagnose,

good luck

 

[4X4HIGH]

Does it overheat at freeway speeds or just at idle?

 

[dremu]

Does it overheat at freeway speeds or just at idle?

Well, this is the '74 K5, which doesn't like to run highway speeds yet She tends to run hot all the time, but I've not taken the time to run the IR thermometer over the hoses to see what "hot" is yet... just thinkin' out loud.

-- A

 

[ssped]

The fans are eigther good or bad. not much in between. Spin it and if it turns free more than 1 turn it is bad. if it is snug and when spun only turns about a half a turn it is good. All tests are done cold. just elaborating on what 90k5blazer said. I would shill check for hot and cold spots in the radiator too.