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#1 |
Registered User
Join Date: Sep 2016
Location: lompoc ca
Posts: 228
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diagnose screech
I have a screech when i rev engine it happens in neutral and in gear only in second my first gear is granny. it is not a belt squeal. clutch fan seems a little tight but its doesnt sound like an airplane. also throttle response seems to lag a bit it only does it when rpm is low and i give it the gas hard.I wouldnt worry but i hope to motor across country and i know a sticky clutch fan robs power lowers mpg
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#2 |
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Join Date: Aug 2009
Location: Bowser
Posts: 13,602
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Re: diagnose screech
It's your fan belt!
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#3 |
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Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,332
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Re: diagnose screech
...or power steering. But it sure sounds like a belt. Why do you say "It is not a belt squeal"?
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1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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#4 |
20' Daredevil (Ret)
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Re: diagnose screech
x2 -- why do you say "It is not a belt squeal"?
I'm very curious what the problem is because my K20 has recently developed a similar noise, usually around 1400 rpm. Doesn't always happen and I've been unable to duplicate it in my driveway. I tried soap on the belts -- adjusted the belts -- finally changed the belts. Still have the noise. I hope it's not the water pump, but I hope I find/fix it before changing coolant. A thought on that fan clutch, if you think it's going bad. Inspect it closely for any hint of fluid leakage. Pay particular attention to the back of the unit, where the shaft joins the clutch. That seal might be leaking, and it's kinda hard to see, which makes it easy to miss. Doesn't take a lot of leakage to begin drying out inside.
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- Mike - 1972 K20 LWB 350/350/205 RIP El Jay |
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#5 |
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Re: diagnose screech
Try some belt dressing Stocker.
https://www.walmart.com/ip/Prestone-...ssing/16817510 |
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#6 |
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Join Date: Sep 2016
Location: lompoc ca
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Re: diagnose screech
thankyou both for quick reply it sounds different more like metal to metal bearing screech and fan seems a little tight i have adjusted belt and no change im thinking bearing maybe alt. but i kind of think its fan clutch just wanted expert opinion ill change out belt to help diagnose n keep it for spare if you advise
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#7 |
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Location: Redmond, WA
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Re: diagnose screech
Well if its not the belt, then that'd leave you with water pump bearing or power steering pump, I think.
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1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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#8 |
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Join Date: Sep 2016
Location: lompoc ca
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Re: diagnose screech
only have one belt i installed good wrench engine with new water pump kept alt. and clutch fan and it did it before engine install thanks again you guys are amazing all of you
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#9 |
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Re: diagnose screech
Likely you have the wrong belt.
How deep does your belt sit in the pulley grooves? |
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#10 | |
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Join Date: Sep 2016
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Re: diagnose screech
Quote:
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#11 |
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Re: diagnose screech
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#12 |
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Re: diagnose screech
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#13 |
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Join Date: Sep 2016
Location: lompoc ca
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Re: diagnose screech
how freely should fan spin when engine is off and cold its kind of tight it does not free wheel. the shaft does look a little oil on it very minor
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#14 |
20' Daredevil (Ret)
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Re: diagnose screech
Hard to describe but I think of it as gooey like it's mired in molasses. It should not spin freely, and should stop as soon as you release it. No freewheeling. Yours sounds normal to me.
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#15 |
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Join Date: Sep 2016
Location: lompoc ca
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Re: diagnose screech
current belt sits flush hope i describe this correctly the belt does not stick out above pulleys and the contour matches pulley it had wrong belt when i got it and i had the guy at auto parts store come out and look belt is two years old has mmm 10k miles on it I will buy belt and change and keep old one as i have spare carb. distrbutor hoses gaskets carb rebuildkit etc nothing wrong with extra fan belt
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#16 | |
20' Daredevil (Ret)
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Re: diagnose screech
Quote:
Anyway I have already changed the belts which suggests there's no belt problem.
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#17 | |
20' Daredevil (Ret)
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Re: diagnose screech
Quote:
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- Mike - 1972 K20 LWB 350/350/205 RIP El Jay |
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#18 |
Registered User
Join Date: Sep 2016
Location: lompoc ca
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Re: diagnose screech
yes pulleys line up
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#19 |
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Join Date: Sep 2016
Location: lompoc ca
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Re: diagnose screech
im sooruy meed break hsnds twitching too much now yhankyou im still teading rrdpondrd responsrd dam phine
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#20 |
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Join Date: Aug 2009
Location: Bowser
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Re: diagnose screech
One last thing to check.
Unplug the voltage regulator and test again. If no squeek then it's your altenator charging strongly that puts an extra load on the belt making it slip. |
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#21 |
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Join Date: Sep 2016
Location: lompoc ca
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Re: diagnose screech
sometimrs i run out of patience i do know how to spell.Anything wring with removinh fan clutvh and starting engine . I only have to ruun it for a moment just thooughht of that
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#22 |
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Join Date: Aug 2006
Location: Redmond, WA
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Re: diagnose screech
You can run it without the fan for a a minute, sure (or less). But make sure the pulley is still bolted on. Don't just remove the fan and bolts! Anything's possible, but it seems like low odds it'd be the clutch making noise.
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1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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#23 |
20' Daredevil (Ret)
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Re: diagnose screech
Yeah, but it *could* be the water pump.... so removing the belt that turns the pump (which also turns the fan), then do a short test run, would help prove or disprove it.
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- Mike - 1972 K20 LWB 350/350/205 RIP El Jay |
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#24 |
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Join Date: Sep 2016
Location: lompoc ca
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Re: diagnose screech
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#25 |
Registered User
Join Date: Sep 2016
Location: lompoc ca
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Re: diagnose screech
if i remove belt and sound goes away then it could be belt alt water pump orfan clutch if its still there then its something rlse sound was there beforr new engine and nrw water pump i kept old alt and fan clutch
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