PLEASE HELP! I just purchased a used 2003 Silverado 2500HD 6.0L with 131000 miles. It has a knock in the engine when I first start it up. It doesn't do it every time I start it up, maybe 50% of the time then goes away as long as I'm putting around town doing 30 or 45 MPH. BUT, it doesn't stop there. The knock returns when I reach about 2500 RPM'S and it gets very loud, fast and constant especially if I'm doing about 70 on the interstate with the cruise control on. It does seem like the oil pressure drops a little when it is making the noise as well. It does it consistently whether it is hot or cold. I have been to 2 different mechanics and both have told me 2 different things. The first one told me he thought it was a timing chain and the second said he thought it was either a rod or a lifter noise. They both used a stethoscope, but the second one actually pulled all the belts and the fan to rule out the front of the engine. He's the one who said he thought it was rods or lifters. If ther is anyone who can help or give me some insight into what is actually going on, I would greatly appreciate it!
Thanks!
Thanks!
