Fan clutch failure?

[FISHBREATH]

Fellows,

I have a 1995 Dodge van with a V6 Magnum engine. I have checked a number of posts in this section, but I am unsure what my problem could be, but I suspect the fan clutch. I replaced the water pump last autumn.

The temperature remains in normal range (normal for the entire time I have owned it since new) at idle and at 30 m.p.h.

When driving on the freeway at 65 m.p.h., the temperature gauge climbs to 3/4 hot.

As soon as I reduce speed back to 30 m.p.h., the temperature drops back to within normal range.

This has been going on for a couple of weeks. I just purchased a new radiator cap and thermostat, but as I think of it, the symptoms do not seem to indicate a thermostat or pressure cap problem. I am drifting to thinking that the fan might be blocking air flow at highway speed.

Any ideas?

P.S. I have not yet actually replaced the thermostat or cap.

 

[EL5DEMON340]

might be a clogged radiator

 

[jw133489]

Check the radiator.. The fan clutch only contributes to engine cooling at speeds under 30. At higher speed the air flow through the radiator is generated by the vehicle speed.

 

[mtandrews]

Check the radiator.. The fan clutch only contributes to engine cooling at speeds under 30. At higher speed the air flow through the radiator is generated by the vehicle speed.

 

[FISHBREATH]

Thanks, guys, I believe I will drain it, remove the radiator hoses, and run a hose through it to check for restriction. Would it make sense to use one of those canned radiator flushes beforehand?

 

[805moparkid]

not necessarily... depends what kind of clutch fan it is. there is a clutch that is rpm based and then the one with a spring that reads the temp coming from the radiator.

to test a fan clutch u put a mark on the clutch and water pump snout. then use a timing light to see if and when there is a differencial in speed.

 

[bremereric]

not necessarily... depends what kind of clutch fan it is. there is a clutch that is rpm based and then the one with a spring that reads the temp coming from the radiator.

to test a fan clutch u put a mark on the clutch and water pump snout. then use a timing light to see if and when there is a differencial in speed.

I agree...A heavy duty thermal clutch fan will still spin at highway speed if the temp is still comming through the radiator hot enough to keep it spinning..if it is bad it will not...

 

[FISHBREATH]

Am I correct in assuming that a freewheeling fan, not powered, will act like an airplane propellor on a dead engine, in that the freewheeling prop will simply block airflow? Freewheeling props can be feathered, turning the blades into the relative wind, to reduce drag.

 

[mtandrews]

we used to take a towel and try to stop the fan with it at idle. A good clutch will just kick the towel away, a bad one will stop turning (I know, I know, old school stuff but that's how I learned).

 

[mopardude318]

we used to take a towel and try to stop the fan with it at idle. A good clutch will just kick the towel away, a bad one will stop turning (I know, I know, old school stuff but that's how I learned).

haha! Ive always wanted to try this....stupid, i know...lol