First, I have a water pump which is weeping a bit. Is it easy to R&R the water pump on a 6L truck?

At warm or cold idle the truck has a rough idle which comes and goes. It'll shake for a few seconds, then be smooth, then repeat. I bought the truck used but it certainly doesn't feel as if there's an aftermarket cam in it. I don't think there would be many who do that in a 2500HD CCLB.

The tires also make a wah-wah-wah sound under certain maneuvers, usually turning or braking. That may be a result of aggressive driving, but is it a safety issue?

 

water pump isnt bad at all, might try some seafoam to clean some carbon buildup to smooth the idle, what kind of tires are they?? check for uneven wear, i dont think its a safety issue unless you can see the belts.

 

For the shaking problem I used 2 cans of seafoam on mine (in the gas, oil, and the brake booster vacuum line), CRC's MAF cleaner, and CRC's Throttle body cleaner.

I took the TB completely off and cleaned the crap out of it. Then i took the MAF out and sprayed the hell out of it. It runs ALOT better now w/ no shake at all.

Also my water pump was leaking too, but mine was just the gaskets, so i just replaced them.

 

I've got a spare can of GM top-end cleaner I'll run through it.

How do you know if it's the gaskets or the water pump?

 

for the stumble, you may want to check the fuel pressure regulator if cleaning the tb does not work. The gaskets on the water pump are fairly simple to replace, we do about 1-2 a week at the Chevy dealer.

 

get underneath it w/ a flashlight and you should be able to see if the leak is coming from in between the block and water pump

 

wah-wah-wah sound could be the unevenness in your tires. Hard cornering, and not rotating your tire will do this. Tires that are not rotated after a while will get out of balance, hence the cupping on the outers of the tires from the hard cornering. What kind of tires are they? If you end up replacing the tires and the nose is till there, it could be a bent wheel depending on weather it's a steel or cast. Put one tire in the air at a time and spin it. You could have just slipped a belt in one of them, or it's a bad shock that's making the tire bounce on the freeways.

 

The tires are Firestone Steeltex 265/75/16's. I've not had them rotated since I bought the truck, about 17K miles. On the car I only do it when I see unusual wear across the contact patch.

The tire tread still basically looks new with the exception of some feathering near the sidewall due to hard cornering. The sidewall itself seems to have some 'creases' in the sidewall. I have to admit I was skeptical about the Firestone brand due to the tread separation problems certain tires had in the past.

What is a slipped belt? I'll try to take it into my alignment shop (which also does alignments on semi-tractors) to see if they can find anything.

 

It's when the steal belts become separated from the tread or the inner part of the tire. Same idea when 18 wheelers loose a chunk of tread.

 

If that happened I would hope it would be covered under the manufacturers warranty