BELT TENSIONER, IDLER, ? CHATTER

[bldn10]

'02 5.3 Tahoe 2WD. I have a chatter or rattle that started very subtle and is getting progressively louder and more frequent. It sounds from the seat like it is in the right front but I do not think it is suspension. It only does it when there is a load on the engine, when it is accelerating. It makes no difference if the A/C is on or off. FWIW I previously replaced the A/C tensioner and subsequently the compressor. Any ideas/suggestions?

 

[corvette744]

Sounds like a tensioner-i would take both belts off and spin and push and pull on everything see if its noticeable.

 

[retiredsparky]

If you still can't find, an automotive stethoscope is a handy, cheap tool to help hear how the various bearings sound internally. You don't place it against anything moving, just adjacent to the idler, pulley, etc.

Also, a digital thermometer can show the running temp. Old bearings heat up as they lose their lube and smoothness.

Fan clutches, harmonic balancers, water pumps, alternators are other sources of weird noises.

 

[M1Gunner]

Also since the compressor was replaced the transmission lines may have been disturbed. Make sure they are properly secured and clear of other components. Also double check the heat shields on the catalytic converters. They may look fine but tap on top especially the passenger side converter. All it takes is one small bead to break. An engine under load will cause the these two things vibrate/chatter at just the right frequency. Food for thought.

 

[OR VietVet]

If it will make the noise sitting still you can remove the belt(s) and accel and see if noise is still there or get to an area where you can start and accel from a stop, with the belt off, and not be in traffic, like a large parking lot. I agree with checking the exhaust shields and all engine/exhaust mounts areas. The recommendation about the mechanic's stethoscope, by retiredsparky, is a great one. I have one and is a fantastic tool in my arsenal for tracking down noises. Inexpensive and a must have. In case you are interested, other must have time savers are a collection of 3-4 different gauges of wire in assorted lengths with alligator clips on the ends, your own cheap code retrieval tool, digital volt/ohm meter-cheap and if you don't have a dedicated bolt and nut drawer in your tool box you will be kicked out of the tech society. Almost forgot, an assortment of nice picks with different ends. Still have my Snap-On set I bought over 30 years ago.

 

[bldn10]

Thanks for all the suggestions. I haven't had a chance to try anything yet but will tomorrow. To clarify, it DOES NOT do it sitting still, it does not even do it driving when off throttle. FWIW I also recently had the rear main seal replaced - don't know what they had to take off to do that. It would be nice if I could put it on them.

 

[M1Gunner]

[QUOTE="It would be nice if I could put it on them. [/QUOTE]

Just pullin the tranny. To access the rear main. If they would’ve left a torque converter bolt loose it you would make the noise even at a sit still. They also pull the y-pipe to remove the tranny. So it could very well be a transmission line that wasn’t secured properly vibrating on something at a certain rpm or the heat shield of the pass side cat doin the same thing.

 

[OR VietVet]

Yea, something left loose or dangling after trans reinstall.

 

[1_8TTony]

Dip stick tube rattling against the firewall???? The 13mm nut which secures the tube is difficult to get to......maybe the shop tech's were too lazy to secure the tube.

Or...

Broken a/c belt tensioner???? I've replaced some broken ones over the years due to cracked spring housings.

Broken sheet metal due to fatigue located at the front tip of the fender where the fender underlaps the hood and bolts onto the radiator core support???

Or...

Broken tab on the face of the a/c clutch.

 

[bldn10]

Would it be the A/C tensioner if it does it even when the A/C is not on?