stock fan/clutch

[cheyenne10]

Has anyone ever experieinced their stock fan clutch going out or stopping working? What are the symptoms? I had a squeal in my sub a while back and have never pin pointed the problem. One think I haven't replaced int clutch on fan. How do these work and do they wear out? Anyone have a good source for new one?

[adamls]

Dont know much about the stock fans but if your going to replace, I think electric is the way to go. My 2 cents.

[Mike C]

The stock clutch can and will go out. Usuallly they lock up first and the truck sets like an airplace taking off above 3k rpm! Then they freewheel and truck usually starts running hot. Then they blow up. GM has discontinued them, but I put a new one on the JImmy last month for $35 and the local O'reilly. Made a significant difference in temp both at idle and on the road. Even on a hot day runs near the 160 deg thermostat. (this was a crutch to help with cooling before I identified the clutch as the problem, I'll be switching back to a 180 most likely.)

[71GMC_3/4T]

The squeal is probably belts slipping because they are glazed or the pulleys are worn out. Try a new set of belts if tightening them a little doesn't help.
My clutch went out last summer. It *does* sound like a jet airplane under the hood. Kills fuel mileage too. If you can move it fairly easily (when it's off!) it's probably alright.

[cheyenne10]

I have tightened and replaced belts but nto pullies. Anyone have a clean good used set for 350 with PS, AC? If I remember right though, I sprayed WD40 on them when squealing and it didn't shut it up.

Still chasing a squeal.

[Longhorn Man]

Mine locked up on the way to hucks place earlier in the summer.
Not only did it drink gas, but it ran HOTTER then it ever had before. I'm talking over 200 degrees (with a 160 T-stat) while I was doing 70 MPH! I still don't understand that.
Mine was not so much squeeling, but sounded like major internal damage. (Huge Visa bill) Sounded to me like bearings without oil before the knocking starts.

[Fred T]

Sounds like either a water pump or fan clutch, since WD-40 didnt quiet things down. With the engine cool and off see what happens when you wiggle the fan blade. Look for wobble and where it is. If you find nothing there, loosen the fan belts and try again, this time look for wobble in the water pump. Also, check for coolant at the bottom of the pump, if there is leakage out the weep hole the pump needs replaced. Still nothing? Check the alternator. Does it turn easy and quietly? Then try the a/c and power steering if you have them.

[cheyenne10]

Checked the loose blade/wobble with and without belt, all tight. Changed out alternator (cheap fix as it needed one anyway).

Never seen a coolant leak (3000 miles in 3 yrs on crate 350 with new water pump)

AC currently disconnected

Squeal sure sounded like belt and that was first thing I checked and checked again. Last time I drove it 250 miles it did it every 1/2 hr at 55mph and then I stopped and shut off for 15 minutes each time and then proceeded 30 minutes or so and repeated.

I also hit a deer that night (no damage luckily from small blacktail deer).

A memorable trip down to the coast to go fishing with my dad!!

Where can a but a good new fan clutch to try (any prefered brand)? Will the used one I have off a 396 work?

[cheyenne10]

TTT

Any more thoughts or a source for good quality replacement fan clutch?

[Andy4639]

I bought mine at NAPA the last time. It has a life time warrenty with it. Check your fan blades also when you get ready to change the clutch, I had to replace my blade awhile back because I lost a water pump bearing. I didn't think much about the blades being bent, so I just took a pair of pliers and bent them back as best I could. I kept having to replace water pumps and a/c clutches before I relized it was because of the blades being out of balance. I replace the blades and have had no more problams since, almost 2 years now. Hope this helps.

[71GMC_3/4T]

Yep, Napa is a good source for a quality clutch.
You got me wondering about spraying WD-40 on the belts. That's something I wouldn't do. I would use spray on belt dressing instead. WD-40 will dry out the rubber, and potentially glaze the belts since it's essentially jet fuel, aka kerosene.
If it's squealing intermittantly like you describe, I would guess it's the belts slipping when the fan clutch kicks in to do its job. Now, the fan clutch could be engaging too tight when it does engage, but I've never seen that happen. Usually they lock up and stay locked up.
Look at the walls of the v-belt groove on your pulleys. They should be V shaped, with a flat bottom. If they are U shaped, or there is evidence the belt has been running at the bottom of the groove, you've found it. The bottom of the groove should be rusty or painted, not shiny.
Has your truck lived in dusty dirty conditions most of it's life? If so, the pulleys are probably shot. When I was farming, we had tractors that would wear out pulleys at 6000 hours, mainly because they were always running in the dust.