jaxnorth

Ok Gang,

In addition to my Z, the wife has a 2000 impala with a 3.4L V6. It leaks coolant around the intake, which is common, and I got ready to tear it down when all of a sudden, we heard a knocking sound from inside the engine. Its not the top valve train, and it will knock a few times when first started, then randomly every few seconds. I revved the engine and it did that fine without knocking, but when the rpm's were dropping off, it would knock. I used the old stethoscope tool and it sounded like the middle of the engine.

I do not believe it is a rod because it is not continually knocking, nor has it come out of the block. My thoughts are a lifter going bad. Now that I have the intake off, I checked and they all have close to the same tension on the pushrods, and nothing looks damaged, or obvious. Before I pull the lifters out, can someone tell me how to check them, because they are $23.00 each and I don't want to have to replace all if I don't have to.

Also, any other ideas what could cause the knock or other things I should look for? I know this is an LS1 forum, but you guys have always helped in the past.....

Jim

tirefryer

It is Piston Slap. If you are not burning oil don't worry about it. They all do it. Just turn the radio up untill the car warms up.

jaxnorth

I wish it was the case.........its the wifes V6....3.4 and it knocks......but not a piston knock....does anyone know how to test the lifters to see if they are bad....I like the radio turned up theory...but the wife would shoot me if I put it back together and did not fix it right........lol

jaxnorth

bump to the top in case someone has a way of telling me how to test hydrulic lifters to see if they are good or not...........