Checking a fan clutch

[Sasquash]

How do you test the fan clutch to make sure it's working properly?



I'm having a problem of getting too hot while towing my 5th wheel. If I'm empty the gauge never goes over 190*f. but if I'm towing up any kind of incline the truck will peg out very quickly. I replaced the coolant already. I do hear a additional fan (or air) noise as it gets hot but don't know if it is correct.



Thanks in advance for any info,



Dan

 

[chuck3]

Maybe a bad thermastat, some of the fellows have had some proplems in that department.

 

[Steve M]

If you're hearing the fan, chances are it's fine. You probably have a thermostat not opening properly. The older style thermostat opened and closed great but owners complained about the temp gauge swinging from 180-160 under light load. So the engineers came up with a soft seat thermostat to stop the gauge action. Now there's a problem with the gauge not opening properly due to the rubber seat. I don't know if we can get a normal thermostat for our ISBs. But replacing the thermostat with a new one will likely cure the heat problem. That's what I'll do first if mine starts running hot. It already acts like the thermostat isn't opening when it should. My previous two Dodge Cummins never even got to the 190 mark. This one does occasionally.

 

[work2muchplay2little]

Check for play (say greater than 1/8") top to bottom and side to side, more is not good. Check to see if you can spin (more than 1/8 to 1/4 turn) the fan by hand (with engine off of course ) if you can spin it it's bad.

 

[trning]

fan clutch

The fan clutch has a thermostat inside. When the air around reaches a certain temp it gets harder to turn. Usually if you get the engine warm and shut off the eng the fan will stop right away. If it doesn't you need a fan clutch. Most likely you just need a thermostat.

 

[Steve Campbell]

It used to be if they failed, they failed in the "on" position. So I agree with Steve M, if you hear it working, it is probably fine.