Squeaking/Squealing when cold

[Willisadam]

2007 Yukon Denali 6.2.

Recently rebuilt. There is a faint squeaking/squealing on start up when cold. Noise completely goes away when warmed up. Removed all belts to eliminate pulley, idlers, water pump, alternator, etc. noise still there. Vehicle has 300k+ miles and it does not look like the transmission has been touched. Has anyone ever heard of a torque converter making a noise like this until warm. Thanks!

 

[Doubeleive]

2007 Yukon Denali 6.2.

Recently rebuilt. There is a faint squeaking/squealing on start up when cold. Noise completely goes away when warmed up. Removed all belts to eliminate pulley, idlers, water pump, alternator, etc. noise still there. Vehicle has 300k+ miles and it does not look like the transmission has been touched. Has anyone ever heard of a torque converter making a noise like this until warm. Thanks!

including the AC belt?
if so and it still makes noise get a mechanics stethascope and listen at the harmonic balancer or at the bell housing that should tell you if it is the tc or not

 

[OR VietVet]

Welcome to the forum from Oregon.

Get a mechanic's stethoscope and that should help pinpoint the noise location. It may be a vacuum leak, especially since recently rebuilt.

 

[Willisadam]

including the AC belt?
if so and it still makes noise get a mechanics stethascope and listen at the harmonic balancer or at the bell housing that should tell you if it is the tc or not

All belts. Problem is it won’t make noise unless revved a little. Pitch and frequency will follow the rpm’s.

 

[Doubeleive]

All belts. Problem is it won’t make noise unless revved a little. Pitch and frequency will follow the rpm’s.

I would grab stethascope and get a helper to push the pedal while you listen
take belts off jack it up so you can get under it and listen from there
should make it easy to determine if it is coming from the back or the front

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.

As stated above, a stethoscope is your best friend here.

 

[j91z28d1]

All belts. Problem is it won’t make noise unless revved a little. Pitch and frequency will follow the rpm’s.

some of the blue tooth scanners are bidirectional and can adjust idle up and down from your phone while you search.. it's pretty handy. especially if your under it on a lift

 

[Willisadam]

Welcome to the forum from Oregon.

Get a mechanic's stethoscope and that should help pinpoint the noise location. It may be a vacuum leak, especially since recently rebuilt.

I thought about that, but dismissed it since i did not think a vacuum leak would disappear after it is warm. Thanks for the tip.

 

[OR VietVet]

I thought about that, but dismissed it since i did not think a vacuum leak would disappear after it is warm. Thanks for the tip.

The vacuum leak can happen with a cold engine and as the engine gets heat in it, while running, metal expands and so can other materials, and then the leak can seal itself. Or something that has vacuum with a cold engine, then does not have vacuum after engine reaches a certain temperature.

 

[petethepug]

Thanks for the ID on the truck.
Was the motor or something else recently rebuilt? Recently, like weeks, months?

Belts .. you can pin point a belt issue at cold start up by removing the belts and running the motor for 30-45 seconds.

When the ail’g belt, pulley or tensioner is quieted up with that belt removed, you’ll be able to isolate it. You should have gotten a totally new accessory belt, tensioner & pulley if you got a new motor. If they gave you a made overseas replacement set, I’d put $ on that.

 

[blondie70]

My bet's on a vacumn leak.

 

[houstontaylor]

With that many miles on your vehicle you probably have a replacement ac compressor belt tensioner, like mine (2003 Tahoe with 344,000 miles). Most of the replacement tensioners seem to be made in Canada, probably by the same manufacturer. I went through 3 of those, one even from a dealer, and they all whistled at certain rpms in cold weather in Colorado (below 20 degrees or less maybe?). I recently looked into replacing just the bearing in one of them and found that bearings have low and high temperature limits. The ones with the greatest range are more expensive. I am guessing that the manufacturer uses cheaper bearings not good for low temperatures. Before I could get around to replacing the tensioner bearing I found another belt tensioner at Oreilly with a different design and manufactured in India (Murray brand I think) and so far it does not make the whistling noise. Don't know if this is your problem but somebody might be able to use this info, if not you.