bbtahoe

Just picked up an 01 Tahoe with 89k miles on it, but you'd never know it, the truck looks almost brand new on the outside and inside. And It drives great too, except there are a couple of annoying noises that I'm trying to figure out what they are.

Maybe someone experienced with the Tahoe can figure it out quickly. The first is a rattling noise when you start to accelerate slowly, it comes from underneath the truck, almost sounds like the muffler is loose somewhere, or is hitting something. But I couldn't find anything, seems pretty solid everywhere, any ideas.

The second noise is a humming noise that's coming from the engine bay, it gets louder with the engine speed, it goes up and down with the rpms. It think it's coming from the alternator, but not sure. Anyone know what it is, and can it be fixed. A mechanic told me that this is normal for a Vortec engine, true?

Thanks for the help.

Gapp

Congrats on a great truck. Don't listen to the mechanic, trust your gut instinct. If something doesn't seem right, go with it. On my '02, I had an annoying rattling noise underneath as well, and I finally pinpointed it to being the front shock cylindrical dust cover. I loosened the shock bolts on top slightly and sprayed some lubricant there. Tightened it back up and problem solved. This may or may not be your rattle, so good luck. As far as the engine noise, you'd have to be more specific as to the sound. Hope this helps.

73shark

The rattling noise that seems to emanate from the muffler may be a loose baffle especially if it occurs in a narrow rpm range and load condition.

bbtahoe

Thank you for the quick responses guys, this is great. I think that you might be right about the loose baffle, since the noise is directly from under the cabin, and at very low rpms. Does that mean I need a new catalytic converter?

As for the other noise, it's actually more like a whining noise from the top part of the engine, gets louder when you race the engine.

Thanks again for the help.

mrlong

if it is a baffle that would only be in the muffler

ZX1100F1

The whining noise is most likely a bad bearing on one of the accessory drive components, spray some oil at the bearing location of the idler pulley first and then go from there to the alternator, use a rag to collect any excess oil so that it doesn't get on the belt or pulleys.
Spray one item at a time and then start the vehicle and check to see if the noise is still present (you get the idea by now). The important part is to change out the part that you find to be the source of the noise.

The rattle underneath could be anything but before you start swapping out parts you would probably be money ahead to have this problem trouble-shot by a good GM Service Center, I have seen some pretty bad rattling noised being caused by some very unlikely culprits like a torque converter lock-up clutch that required only a simple software update.


Dave

bbtahoe

Thanks a lot Dave, that helps. I have an appointment tomorrow at the dealership, I'm having them go through the whole truck, and I'm hoping they can find these problems quickly.

Thank you all for responding.

aknight_sa

i had the same problem with my k5 truck, i thought the ratteling noise was from the muffler.. but it turned out to be from the torque converter... the noise was present when the car was in park, nuteral, and in low RPM...

bbtahoe

Well, just got back from the dealership, and the whining noise turns out to be the power steering pump, which they said was normal (they characterized it as an ambulance siren far away, which is truly what it sound like). And the rattle underneath, they found to be the heat shield on the muffler (hope they're right!).

Thanks again for all the help.