How to diagnose engine squeal?
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Senior User
Joined: May 2007
Posts: 224
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From: Olathe, KS
How to diagnose engine squeal?
Howdy fellas,
My truck has been making bad squealing noises for the past year and I finally got around to doin something about it the other day. I deleted my AC compressor cause i know it was making noise and started her back up.....AWESOME....she still squeals. I can't find this one. It seems to be coming from the passenger side somewhere. Any suggestions on how to find out what it is? I know it's not the alt because I replaced that a year ago and it's damn near brand new.
My truck has been making bad squealing noises for the past year and I finally got around to doin something about it the other day. I deleted my AC compressor cause i know it was making noise and started her back up.....AWESOME....she still squeals. I can't find this one. It seems to be coming from the passenger side somewhere. Any suggestions on how to find out what it is? I know it's not the alt because I replaced that a year ago and it's damn near brand new.
Senior User
Joined: Aug 2007
Posts: 364
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From: Ca
You seem to be looking for the noise around the drivebelt area, so how old is the tensioner pulley? Try spraying some lubricant around the bearing of the tensioner to see if it quiets it down at all.
Other than that, grab a stethoscope.
Other than that, grab a stethoscope.
Senior User
Joined: Sep 2009
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ok, if i read correct your truck has been making a squealing noise for over a year???? if it was a pulley bearing making this noise it would have locked up long ago and fell off. So with that being said i would start by following all the miles of vacuum lines under there for leaks and or collapsed lines. they will make a high pitched whistle/squealing sound sometimes.
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Senior User
Joined: May 2007
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From: Olathe, KS
I know the noise is coming from the serpentine belt. It gets much worse when it rains or it's a heavy dew. It's a constant, almost pulsating chirp. Also, it'll change w/ the engine rpms. I'm curious though how to use one of those stethescopes. I've heard of that but never done it. Would a normal stethescope work as opposed to a mechanic one? I'm a paramedic so I got tons of cheap ones lying around.
Posting Guru
Joined: Jun 2007
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From: Des Plaines, Illinois
You put a new belt on when you removed the A/C, I assume?
The tensioner does have a tendency to squeak as it reaches the end of its life. If it's never been changed, it's a good start.
You can use a mechanic's stethoscope or a really long screwdriver to channel the sound and try and pinpoint it. You might also try a new and different model of belt. Gatorbacks are highly recommended by folks here.
EDIT: Just saw your post. The stethoscope works in the same fashion, but a mech's scope has a much much longer bell, so you don't go shoving your fingers into a fan or something. I had constant squeal than changed with RPM and would actually improve when damp. I swaped a new generic belt for a new gatorback and it went away.
The tensioner does have a tendency to squeak as it reaches the end of its life. If it's never been changed, it's a good start.
You can use a mechanic's stethoscope or a really long screwdriver to channel the sound and try and pinpoint it. You might also try a new and different model of belt. Gatorbacks are highly recommended by folks here.
EDIT: Just saw your post. The stethoscope works in the same fashion, but a mech's scope has a much much longer bell, so you don't go shoving your fingers into a fan or something. I had constant squeal than changed with RPM and would actually improve when damp. I swaped a new generic belt for a new gatorback and it went away.
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Senior User
Joined: May 2007
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From: Olathe, KS
I havn't put a new belt on. The one I put on there is only about 1-2 years old so I didn't think it needed replacin. It looks good. I've always heard good stuff bout gatorbacks though. I'll put one on there and check out that tensioner. I diagnosed my alt and compressor by taking the belt off and spinning it by hand. They both made noise doin that so I wonder if the tensioner will do the same. I'll check it out. Thanks guys.
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My truck has been doing this exact same thing for over a year as well. I replaced the tensioner and that did not help. I replaced the brand new belt with a gatorback and that did not help. I started suspecting either the alternator or water pump. I added some water pump lube into the coolant and it seemed to help, but I still get the squeak sometimes. The water pump has only about 20k miles on it as well.
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Mountain Pass
Joined: Jan 2006
Posts: 249
Likes: 2
From: Moody, AL
Does this squeak only happen when the vehicle is driving? I have a very similar sound, but I can rev over 3grand parked and she is quiet. Once I pull away from a light she squeaks. The harder I hit the throttle the louder she squeaks. I did notice the tensioner pulley moving around yesterday, so I guess I will pick up a new one.
Added: I already have a gatorback belt. I just changed the water pump and alternator. I also removed the mechanical fan and switched to electric.
Added: I already have a gatorback belt. I just changed the water pump and alternator. I also removed the mechanical fan and switched to electric.
Cross-Country
Joined: Jan 2021
Posts: 54
Likes: 18
From: washington state
squeeling noise when idiling
Ok, just read all the comments on the squeeling noise in F150…mine is a 1985 F150 4x4 inline six. I have had the squeeling noise over the past two weeks. Had a vaccum leak, but that is fixed..noise went away for about a day…back again and sounding on passenger side back by motor? all belts are new and have been tightened up again..also sprayed belt spray my husband had, thougtht that might help, but no. Today I will take it out for a drive..havent done that since I live in the ‘out back’ and don’t like breaking down and waiting for a tow…too old for that,especially in this cold weathe..brrrrr…yep, I am a weather whimp! worked outside in construction for 40+ years and one of the great things about retirement? If it is ugly out I do not HAVE to go out…
….also, currently no garage to work in…yet…ok, will go for drive and then start checking the other things I have read on here…thanks for the great thread
….also, currently no garage to work in…yet…ok, will go for drive and then start checking the other things I have read on here…thanks for the great thread
4th Gear
Joined: Apr 2008
Posts: 4
Likes: 1
From: Chicago Area
I had the same thing happening with the serpentine belt on my E350 van. I replaced the tensioner and the belt and it went away...for about 15 months and then came back again. Looked into the idler and that was good, but I replaced it anyway. It was good for about a month.
Finally thought 'WTH and replaced the belt again...it quieted it down completely and has been for the past 9 months.
My parting thought is...don't go cheap on the belt! I got the 'OEM equivalent' from NAPA and it only lasted the 15 months.
Buy actual OEM and save yourself headaches!!!
Finally thought 'WTH and replaced the belt again...it quieted it down completely and has been for the past 9 months.
My parting thought is...don't go cheap on the belt! I got the 'OEM equivalent' from NAPA and it only lasted the 15 months.
Buy actual OEM and save yourself headaches!!!
Cross-Country
Joined: Aug 2023
Posts: 77
Likes: 18
From: CA
As funny as it sounds, belts can develop a wear pattern. If the serpentine belt was put on the opposite way it was on the drive system. Such as being able to read the manufacturer and belt size information facing the radiator or facing the engine / cab. I personally had issues with Gatorbacks on more than one vehicle, but it was for v- belt applications. Specifically stretch and slippage. My go to is Gates. Napa is Gates rebranded. Continental would also be good, but this is just my personal experience. If it is bearing replacement, original equipment is best. Sometimes you can find out who the oe manufacturer is and purchase that. 96 inline 6 belt tensioner is Dayco and it was in my Motorcraft box.
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