High pitched hum - The 1947 - Present Chevrolet & GMC Truck Message Board Network

TeamRinaldi · 11-08-2008, 09:09 PM

Ok, so I've got a new sound. You all know what I mean, you know every sound and squeak your truck makes. Then one day, there's a new one. Hopefully one of you guys can point me in the right direction. It's coming from somewhere on the front left side. I can hear it sitting in the cab and when I crouch down beside the tire, but when I pop the hood I can't hear it. At first I thought power steering fluid, but that wasn't it. It's a real high squeal, like a mosquito in your ear. Any takers?

**old Rusty C10** · 11-08-2008, 09:16 PM

ok so it happens when the truck is at hi idle or running out of park? or does the truck have to be in gear?

TeamRinaldi · 11-08-2008, 10:30 PM

It does it all the time. When it first started it would sometimes stop when I stopped, but now it's constant. It doesn't get louder or softer at rpm change though.

**old Rusty C10** · 11-08-2008, 11:08 PM

something loose on/ near the cat or something on the exhaust shield or something like that?

TeamRinaldi · 11-08-2008, 11:12 PM

I don't have a cat, but I didn't think about the shield. If it's rubbing, then that would make sense. I'll check it tomorrow and let you know what I find. Thanks!

grinch4om · 11-09-2008, 08:24 AM

process of elimination, take off your belts one at a time and listen, also push on body parts in a sensible pattern, that may eliminate or amplify the noise so you can isolate it

Hoods69BadBowTie · 11-10-2008, 02:34 AM

Quote:

Originally Posted by grinch4om

process of elimination, take off your belts one at a time and listen, also push on body parts in a sensible pattern, that may eliminate or amplify the noise so you can isolate it

I would try that and go from there and see what you can figure out.

TeamRinaldi · 11-13-2008, 05:14 PM

Well, it's not the heat shield or any body panel so far as I can tell. It seems to be steering related (I think). It doesn't get louder or softer, but when it's in gear I can make it stop sometimes as I turn the wheel from far left to right. Maybe the pump starting to go?

**old Rusty C10** · 11-13-2008, 06:17 PM

it could be the pump.. i was leaning away from the power steering because you said you dont hear it under the hood.... Im wondering if there is a slight glazing or polishing of the pulley which allows some slippage.. sometimes a bearing in the pump will also make an intermintent sound...

spoon · 11-13-2008, 10:02 PM

Quote:

Originally Posted by TeamRinaldi

Well, it's not the heat shield or any body panel so far as I can tell. It seems to be steering related (I think). It doesn't get louder or softer, but when it's in gear I can make it stop sometimes as I turn the wheel from far left to right. Maybe the pump starting to go?

Does it sound like a "squeal" as apposed to a "hum?" Reason I ask, is my steering is suffering from something like this too. When still and I turn the wheel, it seems like the power steering is having a hard time getting the job done. Everything is fine while driving though.

Mike 85 · 11-13-2008, 11:00 PM

Pull the pump belt and start it up. This will rule out the pump for sure.
Outside wierd chance it's a vacume leak on the brake booster or vac line.
Pull the vac line off the manifold and plug the manifold nipple.
If it's OK,then reconnect vac line and pull the booster fitting and stick your thunb over the end.
OK,
It may be the booster diaphram if it comes back.
Crazy I know but I've found more "problems" that the "normal" solutions don't fix go back to the brake booster.
I've fixed more engine issues than you can count after people have been pulling their hair out and done everything from new carbs to valve jobs because the booster was bad and loosing vacume.

TeamRinaldi · 11-14-2008, 08:07 AM

Thanks for the ideas, I've definitely got some homework this weekend. I suppose you could call it a squeal, but it's really more of a whine. Honestly you've got to find the humor in describing a sound.

It's weirding me out because it's real faint, doesn't do it all the time and I can only hear it on the left side of the truck, predominately on the lower side. The truck's running fine but now that I think about it, I have been getting more road feedback than normal through the wheel while driving. At first I thought it was just rough road (she is 25 after all) but maybe it is the pump. I'll work on it over the weekend at let you know what I find. As always, thanks for the wisdom and advice guys.

TeamRinaldi · 11-18-2008, 05:33 AM

Well the weekend has come and gone, wish I knew what to say. The sound's gone, so I should take that as a win, but where it went, I can't say. Oh well, I guess if it ever comes back I'll know where to start looking. Thanks again for the tips and advice guys.

11-08-2008, 09:09 PM	#1
TeamRinaldi Registered User Join Date: Oct 2007 Location: Sahuarita, AZ Posts: 88	High pitched hum Ok, so I've got a new sound. You all know what I mean, you know every sound and squeak your truck makes. Then one day, there's a new one. Hopefully one of you guys can point me in the right direction. It's coming from somewhere on the front left side. I can hear it sitting in the cab and when I crouch down beside the tire, but when I pop the hood I can't hear it. At first I thought power steering fluid, but that wasn't it. It's a real high squeal, like a mosquito in your ear. Any takers?

11-08-2008, 09:16 PM	#2
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,313	Re: High pitched hum ok so it happens when the truck is at hi idle or running out of park? or does the truck have to be in gear? __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

11-08-2008, 10:30 PM	#3
TeamRinaldi Registered User Join Date: Oct 2007 Location: Sahuarita, AZ Posts: 88	Re: High pitched hum It does it all the time. When it first started it would sometimes stop when I stopped, but now it's constant. It doesn't get louder or softer at rpm change though.

11-08-2008, 11:08 PM	#4
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,313	Re: High pitched hum something loose on/ near the cat or something on the exhaust shield or something like that? __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!! Last edited by old Rusty C10; 11-08-2008 at 11:09 PM.

11-08-2008, 11:12 PM	#5
TeamRinaldi Registered User Join Date: Oct 2007 Location: Sahuarita, AZ Posts: 88	Re: High pitched hum I don't have a cat, but I didn't think about the shield. If it's rubbing, then that would make sense. I'll check it tomorrow and let you know what I find. Thanks!

11-09-2008, 08:24 AM	#6
grinch4om dang its hot Join Date: Nov 2006 Location: frankfort kentucky Posts: 1,349	Re: High pitched hum process of elimination, take off your belts one at a time and listen, also push on body parts in a sensible pattern, that may eliminate or amplify the noise so you can isolate it

11-13-2008, 05:14 PM	#8
TeamRinaldi Registered User Join Date: Oct 2007 Location: Sahuarita, AZ Posts: 88	Re: High pitched hum Well, it's not the heat shield or any body panel so far as I can tell. It seems to be steering related (I think). It doesn't get louder or softer, but when it's in gear I can make it stop sometimes as I turn the wheel from far left to right. Maybe the pump starting to go?

11-13-2008, 06:17 PM	#9
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,313	Re: High pitched hum it could be the pump.. i was leaning away from the power steering because you said you dont hear it under the hood.... Im wondering if there is a slight glazing or polishing of the pulley which allows some slippage.. sometimes a bearing in the pump will also make an intermintent sound... __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

11-13-2008, 11:00 PM	#11
Mike 85 Face your fears Join Date: Nov 2006 Location: Ark. Posts: 883	Re: High pitched hum Pull the pump belt and start it up. This will rule out the pump for sure. Outside wierd chance it's a vacume leak on the brake booster or vac line. Pull the vac line off the manifold and plug the manifold nipple. If it's OK,then reconnect vac line and pull the booster fitting and stick your thunb over the end. OK, It may be the booster diaphram if it comes back. Crazy I know but I've found more "problems" that the "normal" solutions don't fix go back to the brake booster. I've fixed more engine issues than you can count after people have been pulling their hair out and done everything from new carbs to valve jobs because the booster was bad and loosing vacume. __________________ I was told once, You have no BALL'S.... I then handed him my spray gun.......... My Junk

11-14-2008, 08:07 AM	#12
TeamRinaldi Registered User Join Date: Oct 2007 Location: Sahuarita, AZ Posts: 88	Re: High pitched hum Thanks for the ideas, I've definitely got some homework this weekend. I suppose you could call it a squeal, but it's really more of a whine. Honestly you've got to find the humor in describing a sound. It's weirding me out because it's real faint, doesn't do it all the time and I can only hear it on the left side of the truck, predominately on the lower side. The truck's running fine but now that I think about it, I have been getting more road feedback than normal through the wheel while driving. At first I thought it was just rough road (she is 25 after all) but maybe it is the pump. I'll work on it over the weekend at let you know what I find. As always, thanks for the wisdom and advice guys.

11-18-2008, 05:33 AM	#13
TeamRinaldi Registered User Join Date: Oct 2007 Location: Sahuarita, AZ Posts: 88	Re: High pitched hum Well the weekend has come and gone, wish I knew what to say. The sound's gone, so I should take that as a win, but where it went, I can't say. Oh well, I guess if it ever comes back I'll know where to start looking. Thanks again for the tips and advice guys.



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