Hi,

I was wondering if someone could help identify this noise. It's in my 1990 GMC with a 5.7 tbi. It sounds like valve train noise but I could be wrong. It doesn't really change with engine temperature or anything. It started after driving on the highway for about 300 miles. I was asleep in back and apparently the individual driving was abusing it pretty hard to get home fast. Yes I did rev it to show the noise, but it's shut off and won't be started again until I repair.

 

Sounds like a lifter/rocker arm to me, but it is hard to tell from a video. Pull both valve covers and see if all the push rods & rockers are going up and down the same.

 

Sounds like a bent pushrod.

 

I'm agreeing with you on the bent pushrod, and leaning more towards that for sure. Is there any way I can be sure without taking the rockers off by way either a compression test or visually watching it run with the valve covers off?

 

A visual is gonna be needed. Use the old screwdriver in the ear trick to kind of pin point which cylinder.

 

I'm leaning more toward a loose or cracked rocker. at any rate.. pull the vavle cover.