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COOLING ISSUES

You can maybe use a heat gun and blow 300 degree air at the clutch and see if it kicks in. Or if its out it should basically stop spinning on its shaft.
 
Duallykid said:
how can i test the fan clutch?
Click to expand...

Is the clutch is over 5 years old? Yes --> STOP! Replace clutch.

Fan clutches loose 200 RPM per year as the silicone breaks down and parts wear. So 5 years is max effective life from one. Silicone leaks out of the factory clutches by the spring and covers them up in 'oil' like grime. No silicone fluid left - clutch no worky after it bleeds to death like that.

Fan clutches will turn on for morning sickness then kick out. Esp if it was locked up before you shut off the truck.

Kicking off is turning at 20-30% of shaft speed. Full lockup is 80-90% of shaft speed. So be sure the clutch isn't dragging the fan along in full slip.

Bearings go bad and can lock up the clutch.

You can not number the blades and use a timing light to test the clutch on a diesel... ):h
 
well i put the heat gun to it and it was hot as shit,,, and nothing, the fan felt like it got smoother and easier to turn it never tightened up
 
Duallykid said:
well i put the heat gun to it and it was hot as shit,,, and nothing, the fan felt like it got smoother and easier to turn it never tightened up
Click to expand...

Start engine and see if it locks in while hot. The rotation of the clutch while the spring has the internal valve "on" allows fluid to fill the working chamber and lock in the clutch. If it isn't spinning it can't lock up.
 
well. i didn't know what to do so i just replaced it anyway. it WAS THE ORIGINAL, it was $63 at advance, got the severe duty one, cheap insurance, so it's in, and runs 190, to the floor up to 210, but right back down to 190
 
So then your situation has improved with the new clutch? If you want it to kick in a little earlier just look at the free fan clutch mod, you can have it kick in at 205 or whatever just by bending a little piece of metal coil on the front of it.
 
buddy said:
So then your situation has improved with the new clutch? If you want it to kick in a little earlier just look at the free fan clutch mod, you can have it kick in at 205 or whatever just by bending a little piece of metal coil on the front of it.
Click to expand...

Try 1/8 inch first. I'd still recommend re-calibrating the replacement clutch, as GM believed 260 was RED ZONE, not sure when factory clutches are calibrated to engage, but when my TEMP Gauge raed 210, my Scanner read 217. I adjusted mine until it engaged before 210. I had to do a total of 1/4" loosen on the coil. My clutch was about 1-2 years old GM dealer replacement. I'm not sure we've ever seen a cracked block out of an engine that was uncracked, and kept at or under 210.
 
well i don't know if I'm going to go that far with it yet, i'll see how it runs and go from there, i have to keep in mind that i turned the fuel injection pump up 1/4 turn, so i know it will run hotter, i have forgotten exactly what temperature i was running before i turned up the pump, but i can't imaging that it should have changed that much
 
Matt Bachand said:
Try 1/8 inch first. I'd still recommend re-calibrating the replacement clutch, as GM believed 260 was RED ZONE, not sure when factory clutches are calibrated to engage, but when my TEMP Gauge raed 210, my Scanner read 217. I adjusted mine until it engaged before 210. I had to do a total of 1/4" loosen on the coil. My clutch was about 1-2 years old GM dealer replacement. I'm not sure we've ever seen a cracked block out of an engine that was uncracked, and kept at or under 210.
Click to expand...

I need confirmation on changing the factory temp setting on the fan clutch. If I understand you correctly, to REDUCE (lower) the engage temp of the clutch you LOOSEN (reduce) the tension on the coil spring? My pickup is not where I can get to it so a pic would be appreciated if possible.

Thanks, Don
 
Last edited:
96 OILBURNER said:
Yep. You make your new bend closer to the end of the spring, making it longer.
Click to expand...

x2 I did 1/8" then another 1/8" and left it there. Engages around < 205ish. Never engages without plow on, and disengages a few minutes after temps drop down. Perfect.

I would recommend DuallyKid do this too. Factory calibration is too hot.

Don't have a pic, but its super obvious once you take off the clutch from the truck and have it in your hand.

Reseal it with silicone or RTV or anything.
 
Hey, thanks guys!! That link to the pics was great. I thought I was understanding the origional description but needed to be sure. The 94 in my sig line is planned to be a tow rig and I'm seriously looking for mod ideas to make it very dependable. In other words, no overheating problems like they are known to do in stock configuration.

Don
 
handcannon said:
Hey, thanks guys!! That link to the pics was great. I thought I was understanding the origional description but needed to be sure. The 94 in my sig line is planned to be a tow rig and I'm seriously looking for mod ideas to make it very dependable. In other words, no overheating problems like they are known to do in stock configuration.

Don
Click to expand...

That is a fantastic thread that gets reffered to alot.

I think a mod should clean up the off topics and move that into the technical library stickies.

A working fan clutch is as important as it gets.
 
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