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Loud engine squeal and overheating
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m_fenix
New User
Nov 29, 2010, 11:47 AM
Post #1 of 8
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Loud engine squeal and overheating
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A month ago my 1981 Ford Bronco with a 4.9L 6 cylinder started making a squeal. At first it began after I was driving for a few minutes. it started with a low squeal which progressively got worse the more I drove. if I sat at idle the sound would slowly go away.
I had a mechanic friend look at it and of course he said to check the belts. So I changed them. The sound was still there.
He then said it could be the alternator. I had it checked and it was good, but I got a new one any way. The sound was still there.
I then brought to another mechanic who said it might be the water pump. It was a cheap part so I swapped it. This is where things got worse. After I swapped it, it ran fine at idle for a few minutes then the sound came on after a few minutes of idling and extremely loud. It's the loudest I've ever heard it. It doesn't go away and now my engine over heats as well. It never over heated before. WTF!!
I've checked and rechecked my hoses. Everything is good. I used a tube to try and get a better idea of where the sound is coming from and it sounds like its coming from the engine block right behind the water pump and next to the alternator.
There's also a lot of white smoke that dumps out of the tail pipe. I'm assuming this is related.
Please help me. I'm at my wits end here and I don't have money to go to a mechanic. I know it's not a belt issue.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 29, 2010, 2:48 PM
Post #2 of 8
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Re: Loud engine squeal and overheating 81 Bronco 4.9
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Hmmm? Could be a few things still. Is belt tension tight enough? Fan clutch ok? You can either take belt off and spin items by hand or a listening rod (careful with moving parts if you attempt that) to find a bad bearing or source. There are also mechanics stethoscopes - less dangerous to use for that.
Noise and overheat suggests (can only guess) loose belt, fan clutch inoperative w bad bearings, or an outside chance of wrong water pump and another reason for the noise. Not sure but some truck engines are counter rotating for trucks and not for ones used in cars that could have the same size engine and impellers if backwards won't pump the coolant around properly. That wouldn't account for the noise though IMO.
At the moment the only common problem that could cause both overheat and noise would be the fan clutch but can't be certain. There should be near zero freeplay and it might not make a peep spinning it by hand (engine off please) but need engine speeds to act up. Can you feel a decent air flow going thru radiator and is it warm when thermostat is open - upper hose would be warm so you know it has opened. Coolant must be known full too at radiator not just recovery tank.
One more thing to test. Cool engine, take belt off and run engine (short time only) without the belt. If noise is gone the noise would be a belt/belt driven item. If still there there's more to diagnose,
T
(This post was edited by Tom Greenleaf on Nov 29, 2010, 2:55 PM)
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m_fenix
New User
Nov 30, 2010, 11:45 PM
Post #3 of 8
(15499 views)
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Re: Loud engine squeal and overheating 81 Bronco 4.9
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Ok, I’ve tried some stuff. And somehow it went back to how it was before I changed the water pump. I don’t get it. I simply took off all the belts and emptied the radiator then put everything back and refilled the radiator. Now everything sounds fine except after normal driving for a few miles the sound starts up slowly and decreases again when I come to a stop. Then starts back up when I begin driving again.
The belts are tight. It’s not the belts. Also, it’s not the fan clutch. The thermostat is working as well. I’m still stumped.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 30, 2010, 11:57 PM
Post #4 of 8
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Re: Loud engine squeal and overheating 81 Bronco 4.9
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How are you sure it's not belt or fan clutch? When fully warmed up or beginning to overheat you should feel the hot air off the fan blowing hard at the engine. Fan clutches are usually only good for about 5 years. Common item.
If you watch warm engine and have a helper just shut motor off the fan clutch should stop in about one turn or it's junk. Right now it's the only common denominator I can think of for both noise and overheating,
T
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m_fenix
New User
Dec 1, 2010, 9:32 AM
Post #5 of 8
(15488 views)
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Re: Loud engine squeal and overheating 81 Bronco 4.9
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I really appreciate the help. Thanks.
The reason I know it's not the fan clutch is because that year of Bronco doesn't have one. Or at least mine doesn't. Also, it's not overheating anymore. The temp is good. I just don't get it.
Here's everything that happens: When I first start it, everything is fine. No sound. No overheating. After it's warmed up and I start driving, the sound usually starts about a mile or two down the road. When it does start My speed reaches about 35 MPH. Once I come to a stop the sound slowly starts to lessen and eventually go away. I returns again once I start driving. And this repeats.
When I pull over and listen I hear the location of the sound is around the alternator, which is bolted to the lower front part of the block. I know it's not a belt tightness issue. There's no tensioner either because it doesn't have a serpentine belt. The power steering, alternator, and smog pump all have their own belts which come off the water pump.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Dec 1, 2010, 10:54 AM
Post #6 of 8
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Re: Loud engine squeal and overheating 81 Bronco 4.9
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If I missed it - sorry. Will this noise quit with the belts off? Important to know that so we can stop looking for anything belt driven.
Overheat (think already said) could be a suddenly clogged radiator but again that doesn't add up with conjunction with noise??
Right - if no fan clutch and it's blowing the correct way that wouldn't be it.
Again - feel for heat blowing thru the radiator. If nothing we need those clues to narrow down an approach. Noise is frequently fussy to find and diagnose. There could be an engine bearing for noise and yet again don't think that lines up with the overheating?? It's hard not being there with this issue,
T
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m_fenix
New User
Dec 1, 2010, 3:39 PM
Post #7 of 8
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Re: Loud engine squeal and overheating 81 Bronco 4.9
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There is no sound when the belts are off and the engine is running.
The radiator is flowing fine as well. No clogs.
I know it’s difficult to diagnose not seeing it. Thanks for trying.
What bearings could it be?
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Dec 1, 2010, 5:41 PM
Post #8 of 8
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Re: Loud engine squeal and overheating 81 Bronco 4.9
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That's good news as a belt driven item should be cheaper and easier than some internal problem. Again - feel for warm air flow coming from the fan when t-stat is open. Repeat - is fan blowing the right way?
Hey - anyone jump in. I can't think of anything but a bad fan clutch so far still that can both make noise and allow over heats when everything else checks out.
T
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