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#1 |
Senior Member
Join Date: Apr 2000
Location: Oregon
Posts: 2,512
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stock fan/clutch
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?
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Bob |
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#2 |
Gotta Startem Early
Join Date: Oct 2001
Location: Amarillo, TX, USA
Posts: 364
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Dont know much about the stock fans but if your going to replace, I think electric is the way to go. My 2 cents.
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67 SWB In Progress, one piece at a time, maybe 3 years I will be finished |
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#3 |
Registered User
Join Date: Dec 1999
Location: Austin, TX, USA
Posts: 7,720
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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.
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44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax |
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#4 |
Weapons Of Construction
Join Date: Apr 2000
Location: Colorado, USA
Posts: 1,095
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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.
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1971 GMC 2500, 402/TH400 4.10 Daily Driver Lafayette, CO |
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#5 |
Senior Member
Join Date: Apr 2000
Location: Oregon
Posts: 2,512
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squeal
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.
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Bob |
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#6 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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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. |
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#7 |
Cantankerous Geezer
Join Date: Aug 2002
Location: Bel Aire, KS
Posts: 6,264
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Sounds like either a water pump or fan clutch, since WD-40 didnt quiet things down. With the engine cool and off
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Fred There is no such thing as too much cam...just not enough engine. ![]() |
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#8 |
Senior Member
Join Date: Apr 2000
Location: Oregon
Posts: 2,512
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summary so far
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?
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Bob |
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#9 |
Senior Member
Join Date: Apr 2000
Location: Oregon
Posts: 2,512
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TTT
Any more thoughts or a source for good quality replacement fan clutch?
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Bob |
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#10 |
Old member
Join Date: Jan 2002
Location: Liberty, & Garden City S.C. , U.S.
Posts: 19,936
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![]() ![]() 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.
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1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 ![]() Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs. |
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#11 |
Weapons Of Construction
Join Date: Apr 2000
Location: Colorado, USA
Posts: 1,095
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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.
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1971 GMC 2500, 402/TH400 4.10 Daily Driver Lafayette, CO |
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