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Discussion Starter #1
I have a 1994 D21 4x4 with a KA24E engine. When I bought the truck (with 167k miles on it), the temperature gauge didn't move at all. I replaced the temperature sending unit and now it moves but only the width of 2 needles after running for 30 minutes!

The heat i get is luke warm at best. Can my vehicle be overcooling? I live in CT and right now the temperature outside is pretty cool (~25 degrees) but yet as soon as i start the engine, the cooling fan is running and never shuts off. Is that normal for these engines or should the fan come on and off when necessary?

Is the clutch electronically controlled in any way or is does it have a bi-metal switch that turns it on independent of the car's computer?

Thanks,
Chris
 

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Discussion Starter #3
The Haynes manual says that the clutch is part of the water pump but the service manual seems to imply that it's not.

Can the clutch be replaced seperately? Will it require me to completely drain the coolant and remove the radiator?

Thanks,
Chris
 

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Discussion Starter #6
could it be a stuck open thermostat
That's why I was questioning whether or not the fan should be spinning all of the time. Does the clutch adjust the speed of the fan in this model or should it completely engage/disengage the fan?

Is there an easy way to test whether the clutch is working properly?
 

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i would start with a thermostat then flush the heater core the fan clutch will not overcool the thermostat will open and close to keep the temp right but the heater cores can stop up not allowing good coolant flow throu them resulting in poor heat the fan clutch try to spin it by hand while engine is off and cold it should spin freely the get engine hot and try to spin it with engine off should have more resistance let us know what you find
 

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i would start with a thermostat then flush the heater core the fan clutch will not overcool the thermostat will open and close to keep the temp right but the heater cores can stop up not allowing good coolant flow throu them resulting in poor heat the fan clutch try to spin it by hand while engine is off and cold it should spin freely the get engine hot and try to spin it with engine off should have more resistance let us know what you find
you have that backwards. fan clutch will have some resistance cold and easier to spin when warm. if it doesnt change then you have a bad fan clutch.

I would start with the t-stat as well, its either stuck open or not there, when you flush the system be sure to have the heat all the over to hot and be sure to get all the air out of the system. this could also be your problem by having an air pocket at the temp sensor.
 

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Discussion Starter #16
I'm not done putting everything back together yet-the adjustment bolt on the alternator belt snapped off so now i need to take the alternator out and drill out the piece of bolt left in it.

Anyway, the fan clutch was definitely bad. The little center bimetal piece and the shaft it turns looked rusted over. I tried turning it with a pair of needle nose and it wouldn't budge. I sprayed it with WD-40 and it finally made a squeaking sound but it moves freely now. I don't trust it though so i bought a new fan clutch.

I also got to the thermostat which works properly (ie. It opens at 170 degrees) but it doesn't seem to close completely. The rubber seems hard and there's a slight gap when it should be closed so i'm replacing that too. We'll see if i can get some damn heat when everything's back together.

Thanks for the help!
 

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Discussion Starter #18
Everything's back together and the temperature gauge rises up to about 1/3 to 1/2 up the scale and most importantly......the heat works!!

In the process, the alternator belt adjuster bolt broke off inside of the alternator so i had to drill that out...It's never easy.
 
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