2010 5.3L “Rattle”

sideout999 · March 2, 2019

Alright-

high Miller here- 445 KM, (276000 miles) tranny rebuilt at 350.

in the past month, I have noticed a rattle. Not steady, inconsistent,

It is not-

piston slap- present when engine is warm

lifter- inconsistent

lifter gone- zero power loss, truck runs great, drives great, no loss uphill.

highly doubtful

cat converter.

Possibly AC clutch? Bearing in that area?

It sounds like it’s coming from that area.

Truck straight on, bottom left.

I cant test because of GMs safety feature with the outside temp gauge on AC and stopping it (3 blinks) (Canadian winter)

Has had anyone just cut this belt and said eff the AC? I have zero use for AC, summer I roll the windows down, I think it’s a waste of gas to be honest.

Been through pretty much everything else.

More of a nuisance then an issue. Truck drives great, no lights, nothing. Mileage dropped a bit, but could be Canadian winter.

Im tempted to cut the belt, as it appears it’s got its own belt and from diagrams that’s what I can see.

Thoughts?

Tia

riverbanks · March 3, 2019

Try it, good way to isolate a possible noise from there

HAZCHEV03 · March 3, 2019

Just cut the belt on mine a few weeks back. Bearing in the AC was going and I also had a rattle. The rattle turned out to be the tensioner for the AC, it had no tension at all and I could move it with my hand. That is more than likely your issue.

Sent from my iPhone using Tapatalk

jfath14 · March 5, 2019

I have a rattle in first gear on a cold start. Any ideas?

sideout999 · March 5, 2019

So- i have it narrowed down to the waterpump.

I loosened the belt tensioner, and spun the wheel for the pump and there is a definite roughness and noise to it, and that was at 1/1000 the rpm, and explains that if the bearing inside is worn down. Or uneven, it makes it inconsistently as it may hit a good part of the bearing and run for a while. I think one of the bearings are gone, and from what I can see, it is the original pump on it. Has a GM stamp and all.

New pump from amazon is on is on its way, $150 CAD as opposed to local shops wanting $400 plus for the same thing. Going to do thermostat etc at the same time.

I spun the tensioner, Alternator and a few others and they were all smooth. This was the only one off one.

Thanks all.

( I didn’t cut the AC yet lol)

HAZCHEV03 · March 6, 2019

I would still check the AC tensioner. You don’t have to cut the belt, just slide underneath and if the tensioner is shot you should be able to move it with your hand. Mine had no tension but it was somehow still holding the belt on, belt was cracked to all hell so I cut it, took the tensioner completely off, then pulled the relay and fuse for the AC.

Sent from my iPhone using Tapatalk

sideout999 · March 7, 2019

Replaced water pump, took about 30 minutes.

Sound is gone.

No need to cut the AC now, Although I may still, as well as pull the fuse, relay and throw one of those dummy loops in it.

Thanks for the help!

SierraHD17 · March 7, 2019

On 3/6/2019 at 11:45 AM, HAZCHEV03 said:

I would still check the AC tensioner. You don’t have to cut the belt, just slide underneath and if the tensioner is shot you should be able to move it with your hand. Mine had no tension but it was somehow still holding the belt on, belt was cracked to all hell so I cut it, took the tensioner completely off, then pulled the relay and fuse for the AC.

Sent from my iPhone using Tapatalk

He doesn't have an A/C tensioner assembly on his truck. That's a Gen 3 thing with the GMT800 trucks. With his 2010 it's a stretch fit belt and no additional little tensioner.