2006 LS Perplexing Engine Noise

Hello,

I have a 2006 Avalanche LS 5.3 with 118,000 miles on it. I have always taken great care of the vehicle (oil changes, scheduled maintenance, etc.), however it's making a loud squealing noise that I just can't put my finger on. I've searched and read a lot of post and was wondering if anyone had any ideas. Any help is appreciated.

YouTube Video of noise: https://youtu.be/1_qr-Zt3hfo

To help narrow down the problem I have;

• Had all belts, pulleys and tensioner pulled - same noise is present
• The noise is present in park, idle or in any gear (forward/reverse)
• The noise does speed up with higher engine RPM
• It seems the noise is more noticeable when around the wheel well (see video)
• No codes are being reported
• Oil pressure and consumption are fine
• I did do an engine flush with Gunk Motor Medic (changed oil afterwards) and had the transmission fluid drained and new filter (no help)
• Truck runs fine otherwise
• The noise starts as soon as the engine is started and doesn't stop until the engine is turned off
• A mechanic who is a friend of my brother-in-law (he pulled the belts, pulleys, tensioner, etc.) said "it sounds like it's coming from the lower rear, but it's really hard to pinpoint without starting to pull things apart and costing a lot of money. He said just to drive it until something breaks (if it does) and then decide what I wanted to do.

I would really like to get this taken care of, it's pretty loud and can be heard inside the cabin while driving. Thanks for any help or suggestions.

Internal squealing noise could be a bearing, lifter, valve spring.. If you pull the rocker covers and look at the top end, look for a loose pushrod/rocker arm. Find anything loose and probably a lifter and/or cam lobe..

If it's a bearing it will have to be torn down and rebuilt...

Only problem with driving until it breaks is the possibility of further damage through out the engine with broken pieces. Open it up right now and you may get away with lifters/cam.


Good luck

It does sound like something in the valve train, I spun a bearing before and it was knocking.

Like Randy suggested take the valve cover off and see if any rocker are loose

Possibly:
cracked flywheel or other issue (engine runs fine but the crack usually makes a higher pitch "Squeak like a bad u joint")
bad crank or cam bearings - Usually see oil pressure issues and god awful noise.
BAd lifter - runs bad
Broken Valve spring - Runs bad.
Cracked leaking exhaust manifold -

SO you had the drive belts off when you ran the engine? IS that what you mean or did you just swap out?

I would look under valve covers first or maybe visit a few different mechanics shops for opinions.

Anyone turn over engine by hand and feel and listen?

Did it happen suddenly?
Recent work done?
Little history of what was done prior to noise and when did you first notice noise?

Take it to another mechanic.  Someone who knows how to use a stethoscope. Yeah....it could be anything with a bearing that is driven by the engine or even a torque convertor.  A good mechanic will isolate the problem before pulling stuff apart.  I'd be surprised if it was in the trans but it is possible.  Typically those noises get worse and the problem will become more obvious with time.

Linescreamer said:

Take it to another mechanic.  Someone who knows how to use a stethoscope. Yeah....it could be anything with a bearing that is driven by the engine or even a torque convertor.  A good mechanic will isolate the problem before pulling stuff apart.  I'd be surprised if it was in the trans but it is possible.  Typically those noises get worse and the problem will become more obvious with time.

Click to expand...

Thanks for the quick responses. Had the truck back in the shop today (know the owners through a friend) and they said it's absolutely internal and they are 99% certain it's a bad cam bearing. They said drive it and decide what I want to do. They are a Jasper preferred installer and will be getting me a quote on the Jasper and a used motor. They said both come with a 3 year/100,000 mile warranty.

Was told labor for the Jasper would be $1430 and they would call Jasper on Monday morning, they closed today at noon. I looked up my engine on Jasper and the price is $2713.00. I don't know if they get any discount or not. They told me less than a week to do the install. I'll compare the cost and pros/cons of the Jasper or used when I have all the numbers.

I may just drive it until there is no choice but to replace it. I'd rather pay 4k than 30k for a new truck.

Does $2700 for the engine and $1400 for the labor seem about right? I've never had to replace an engine before.

Thanks again.

Doesn't sound like a bad price.. Go for it..

The price isn't bad.  Don't go for it now.  I would be checking oil pressure and for metal in the oil.  Cam bearings usually go bad by spinning and don't make squeaking noises.  Besides...that engine...running smooth with 118K miles shouldn't need cam bearings.  It really sounds like an alternator, flywheel or power steering pump to me.  Again, a good mechanic would be able to pinpoint it.  A Chevy "A" mechanic who is familiar with that engine most certainly would be able to pinpoint the noise.

Linescreamer said:

The price isn't bad.  Don't go for it now.  I would be checking oil pressure and for metal in the oil.  Cam bearings usually go bad by spinning and don't make squeaking noises.  Besides...that engine...running smooth with 118K miles shouldn't need cam bearings.  It really sounds like an alternator, flywheel or power steering pump to me.  Again, a good mechanic would be able to pinpoint it.  A Chevy "A" mechanic who is familiar with that engine most certainly would be able to pinpoint the noise.

Click to expand...

Thanks for the feedback. I think I will suck it up and pay the dealership to take a look. Just need to find one with a great, and honest, mechanic. I just don't see how it could be something like the alternator or power steering pump when all the front belts, pulleys, etc. have been pulled and the noise is exactly the same. And I would think one of the two places that already looked at it would have isolated it to the flywheel area and not the engine if that was the case.

I will keep the thread updated after Chevy takes a look.

Thanks.

My Avy just started making a very similar noise, it increases with RPM and sounds like a lifter but it is more of a squeak and after adding abut a 1/2 quart of Lucas heavy duty oil stabilizer it has quietened down some to where it is no longer there at idle but only under load on acceleration.  Prior to adding the Lucas it was really loud sitting at idle and especially if I revved it up a bit.  My mechanic strongly believes it my be a rod bearing so it is going in on Monday for a new crate 5.3 all stock at a cost of approx $7,000 complete stem to stern R&R and then with an extremely heavy heart, I will be getting rid of her.   I absolutely love her but this is the last repair bill that I can handle.  In the last 4 years alone it has cost me over $10,000 in rear diff costs, she is never beaten and has not been off road in at least 5 years now.  The "typical GM" problems have finally got to me at least with this vehicle.  I don;t want to rant on for too long, I am sure many of you know the downfalls of GM "quality"  I think that I have probably pretty close spent in repairs, what the Avy originally cost me, so no one can say that I ever gave up on her......till now.

Man that sucks, I know you really liked it.

I hope you demod her before you turn it in.