Is my fan clutch working?

[CoachWagner]

Does anyone know how to test if a fan clutch is working other than just listening for it? I don't think it ever worked since I had it for the last year, so I don't know what I am supposed to hear.

[slagona]

I didn't hear my fan clutch engage (becase it didn't) for over 45K miles/15 months. It hasn't engaged since! When/if it engages, you will know!!!!

If your temps don't get above at least 200 *F, your clutch probably will not engage. Mine engaged while pulling an 11K lb trailer up a mountain pass (big hill) on an 80*F day. Engine temps were a little over 200*F, EGT's were just under 1100*F pre-turbo, trans temp was under 210*F - don't remember exact temps.

The clutch engaged twice during that trip from NY to FL - both near the top of a long hill. Coming back with the empty trailer, it did not engage.

So, unless your towing, it's quite possible your fan will never engage.

--Scott

[john8662]

I hear my clutch on my 1995 every time I start it once its been sitting hot. When I take off to accelerate I hear the fan whine for a while then spool down. The clutch was engaged because of the heat soak under the hood (its really freaking hot under the hood of these trucks just after shutdown).

Ditto on the pulling and hearing the clutch. Mine won't engage pulling a trailor steadily down the highway until the water temp gets to about 215 with the A/C on. Thats why I'm going to the Kennedy Clutch, its not that there is anything wrong with my clutch, it just engages too late. I was pulling a 4-5% grade two weekends ago in New Mexico with 4k in trailer behind me. By the time the clutch kicked in I was already nervous about temps. But when it did, temps soared downward. This is with exhaust guage sitting at 1100 degrees steady running 40mph (yeah the semi's passing were probably laughing at me!!!!) but I kept everything in safe limits. I would like the temps to stay low to have a larger safety margin, which a better clutch will give you. If you don't pull, and have a stock degree stat, then don't worry about it upgrading, just make sure your clutch works. I also have the dual stat upgrade.

[HANK1948]

Yep mine is the same way, loud as all hell most of the time then eventully quieting down after I speed up. Iam sick of the noise it would be great if I could here the turbo and the engine instead of the fan, my old relieble 6.2 doesnt make any noise, thats why Iam going to get a D-MAX fan and quiet her down.

[Scooby]

You could check the fan after driving the vehicle a while, then parking and letting it sit for a while. The heat coming off the radiator after you park shuld engage the clutch. Try spinning the fan by hand, and you should find quite a bit of resistance. If it freewheels, or turns real easily, it is bad. This is a crude check, cause it will find only clutches with little or no silicone, or lockup left in them. I do a lot of A/C work, and I have found if it is over 5 years old, and the A/C is not cooling well, replacing the fan clutch helps get the air moving across the condensor coil, and the A/C works much better.
Bill Heath sells a severe duty fan clutch that is supposed to lock up earlier than the stock one did, and help with cooling problems caused by low airflow and late clutch lockup. I bought one, but have not had a chance to put it on yet.

[TurboDiverArt]

If you are using the A/C it will also come on faster as the air coming through the condenser of the A/C unit is hot after pulling the hear from the Freon. I notice on a day above 90 degree with the A/C on, on the highway (cruise control 70 MPH) that the fan will occasionally come on. When towing with the A/C on the fan will cut in and out on the highway. You'll hear it when on. My truck's never been above about 205 but I do hear it some on at about 195 or so.

As far as I know I have the stock or replacement clutch fan. I've never changed it but I'm thinking of going to a JK unit depending on how the truck does towing in August heat.

Art.