Engine Squel

[nbkratzer]

I have a 2006 Sierra, 4.8 litre. It recently developed a squel, that sounds like a belt squel. I checked the belts, and they are fine. I removed all the belts and started the truck, and it still makes the noise, the only thing turning is the crankshaft balancer. So, I've pretty much decided that the crankshaft balancer pulley has to be the problem. Would any of you have any other thoughts on possible causes. My Dad seems to think that it could have something to do with the timing chain. I'm really hoping that it's only the balancer pulley. Thoughts?

[SILVERADOSC540]

The idler pulley would be my guess. Cheap and easy fix.

[nbkratzer]

Its not the idler pulley, like I said I pulled the belts and ran the truck, still makes the noise. I'm still thinkin its the balancer, just hoping its nothing more serious.

[SILVERADOSC540]

Missed the part on pulling the belts. Talk your dealership or another mechanic into a free diagnosis. I may be mistaken, but I think the harmonic balancer is bolted directly to the crank and has no bearings. Hopefully it's not the front main seal. Does the pulley run true when the motor is running? Any play in it when not running?

[nbkratzer]

My cousin works for Ford I'm gonna take it by there tomorrow. See what he says. I believe your right that it bolts directly to the crank so there aren't any bearings, but I've seen on a couple other forums where the sleeve can cause a squek. Its actually more like a chirp than a squek. As far as the engine goes, its running fine. Just like normal, oil pressure is good, its just got that damn noise and its driving me nuts.

[Gurrzt]

There is a "tensioner" located off the engine block that the serpentine belt rides on, it is a spring loaded unit, and as time and wear go on, it loosens and causes the belt to squeal.

 

Sara (2001 Z28) would talk to me regularly until I had the tensioner replaced.

[txab]

Did you read the the op? Makes noise with NO belts on.

[VMaxtastic]

Both my 2000 4.8 liter, and my 2007 6.0 squealed like crazy after about 140,000 km. Never bothered addressing it in my 4.8, and drove it to 400,000 km.. Did annoy me though. Was worse in the cold. I had the tensioner changed on my '07, and it did eliminate the squeal... For a little bit anyway. But if it does it with no belts, pretty much means its one of the moving parts, so my input is useless haha

[Gurrzt]

Did you read the the op? Makes noise with NO belts on.

 

My bad!