running hot, bad clutch on the fan?

[HANK1948]

How do you know if the clutch on the fan is engaging? my truck seems to run hot just driving on the e-way today it was 80deg (outside temp) and driving 75mph it was running about 215 and if push it up a hill it will climb to 230 no problem thats with no load behind me, and if i run the a/c it will keep climbing :confused:

[CareyWeber]

I have allways been able hear my fan when the fan clutch engages. By 230

[Cooperrw]

With the 97 cooling mods on my 96 the temps never get over 200 deg (with out a load) even with the outside ttems hitting 110 and the A/C on. The new fan is much quiter but I can still here it coming on. :cool:

[Peter J. Bierman]

When driving 75 MPH I doubt if the fan would do any good, the wall off air you try to push through the radiator is more the any fan would pull through.

Check the radiator for bugs and leaves and check all other cooling components, I think there is some thing else that couses the heat problem.

Peter

[Kennedy]

Actually, driving 75mph across the plains EMPTY coming back from the 99? Rendezvous is what motivated me to build my clutch. Truck ran hot, AC pretty much not existent etc.

Lots of factors like aerodynamics, and static pressures to consider.

[Turbine Doc]

Hank,
before condemning the fan clutch thermostat if you havent done so already flush the rad & ac condensor fins from back side LOTS of stuff gets in there after a while. THe JK clutch is a good mod if you still have cooling probs after you verify the heat exchangers are free to flow air. maybe too a radiator flush is in order if you weren't 1st owner and know coolant was regularly changed

[JohnC]

The fan clutch should be engaged when you first start up in the morning. If you pull away immediately you should hear the fan for a half a mile or so, then suddenly the noise level will decrease as the fluid gets evenly distributed. If you don't then the clutch could be bad. Also, with a cold engine there should be noticable resistance to spinning the fan by hand (engine not running...)

The temp gauge is of questionable accuracy and the clutch is only indirectly related to water temp. (It reacts to the air temp around the clutch). Anything that allows cold air to get around the radiator could delay clutch engagement. Also, there are reports that the clutch will engege if the rpm difference is momentarily reduced (back off the throttle for a second).

All that said, I think when mine engages the gauge is reading about 230. I suspect it reads about 10 degrees high.

[HANK1948]

is there any benefit to running the fan with out a clutch? direct drive, also is a D-MAX fan alot quieter than mine?

[Billman]

A benefit of running a fan without a clutch? I assume you're referring to direct drive? Yes it would be fully engaged--all the time. Disadvantages are that it is power robbing and really not needed.

Yes. A DMax fan blade(21" Composite) is quieter.

[cruzer]

Peter B. I have run 70-75mph loaded,the fan clutch would engage and bring down temps from 200* to 180*, then disengage. I'm running the 20"
later model fan. 9 blades IIRC, and a new GM clutch. My old 93 6 blade fan and clutch used to engage around 230*.

[Peter J. Bierman]

The only time my (home made ) 21 inch fan engaged was when asking power with low speed a longer period.
I run a pack off 4! heat exchangers, intercoolers, A/C condenser, radiator and engine oilcooler, one after the other.
A lot off cars that have electric fans would engage only on a hot day in city traffic.
That's why I thought it would not make much differance, but if you found it to be otherwise, it's fine with me.

Peter