Well I bought another first Gen last week and have some questions.

The fan clutch is always engaged which I assume its bad but is there something I can check first?

Also ever since I put the hx35 from my 96 on it I can't get the oil drain to stop leaking. I have made gaskets 5 times retrying It but It still leaks. I have made sure there are no cracks in the drain and the mating surfaces are clean. Will it leak if its over tightened?



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I just replaced my fan clutch, cost about $50 or so. Just remember the nut on the fan is left handed thread.

As far as the turbo oil return, I would try some red rtv on it since you have already tried it numerous times. I have never done it myself, but thats what I would try.

 

An always engaged fan-clutch is far better than the usual ones that never seem to engage and just coast sleepily along, while the refrigerant boils itself to oblivion in the condensor.


It is very possible that your clutch has been purposefully locked by the previous owner; I know that I lock every one I get ahold of.


If you do buy a non-locked fan-clutch, be sure to hang onto the one you have now, as you will be wishing for it when summer rolls around again.

 

I don't understand why someone would want to keep it locked all the time.

I have never had a problem on these trucks with the fan clutch working normally. Its Just annoying more than anything. How does someone manually lock the fan clutch?

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As for how to lock the fan, I drilled and tapped the hub in two places and ran two 1/4-20 machine screws into the hub and rotating internal assemble.

As for why. I have had a run of bad hubs and I keep the modifiied hub in hot standby (that means collecting dust on a shelf in the garage) for the day the other one quits.

 

My fan clutch seems to be locked up all the time. I tried slowing it down with a funnel after the engine was about 125 degrees, but it didn't stop anything.

The stock fan clutch is not available from the dealer. (PN 52006096) After he said the '89 clutch wasn't available, he told me they stopped using that particular one in 91.5. I then asked him if he could get one for a '93, and he said that it is actually the same PN from '89-'93 (to his surprise). Are Napa clutches any good? I know it seems to be just a parts merry-go-round sometimes until you finally find one that works right. I've also read about using a clutch from a newer truck, and I will consider doing that. The main problem I have now is that my engine will never get up to temperature. I've changed the 'stat twice in the last year, and the old one I took out was working fine (according to a pan of hot water).

 

Make sure there is nothing blocking the heater core. I had the same problem, changed everything from the water pump, radiator, T-Stat, fan clutch (which I got form NAPA without any problem) and it wasnt until I unblocked all the leaves and debris from the heater core that everything went back to normal....I dont understand why, but all is good now for heat. Hope this helps

 

It don't really have problems with the heat, it's just that the engine coolant itself doesn't get up to temperature.

I picked up a clutch for a 94-02 today and just stuck it in there. I'm about to go out and see how it does. (Really no difference whatsoever other than being about 1/8" shorter.)

 

If the engine won't come up to temp the problem is the thermostat not the fan, the t-stat keeps the coolant in the block so it has a chance to heat up and then regulates the flow to maintain it. The fan only works on the coolant in the radiator and of course cooling the engine compartment.
A locked fan wastes horsepower.

Jim

 

Thanks, Jim.

I agree with both points you make. However, I had these symptoms last year, so I replaced the thermostat. That changed nothing. Just to make sure, I put the old one in a pot of water, then watched it open and close back at the correct temperature. I don't think the stat is the problem. If you have any reason to think it could still be that, please explain further. I did use a Napa T-stat.

EDIT: I also tried the new clutch, but it did not spin freely even after 10+ minutes of running and driving. I guess I'll take that one back tomorrow.

 

So are you sure your Engine Coolant Temperature gauge is working accurately?

 

I just put in an Autometer electric temp gauge.

 

Well, took the new clutch back today, and I've just been driving it without a fan at all. Still isn't even getting over 150 without cardboard. The stat isn't opening yet, though, so I don't get why it won't get warm.

 

Is it possible you have an air lock and the sensor is not reading the temperature correctly?

You can have an air lock and be low on coolant and the heater will blow cold air.

Do you still have power? maybe you are not generating very much heat? AFC stuck, diaphragm torn.

Thermostat installed correctly?

Where do you live, what is the ambient temperature?

 

I recall a TSB from back in the day regarding a Overheat/No Heat condition in some of the Cummins in the '89-'93 trucks. The head needs to be checked where the thermostat rests. Some heads were known to have a little extra material in the casting that caused thermostats to bind open or shut. Thermostat kits from Cummins consists of the thermostat, a seal and a template which is used to tell whether yours is good or needs some iron removed from the head to remedy the binding. Thermostat "kits" from mom and pop shops or anywhere else won't have this template.