I recently purchased a 760 turbo that has an engine noise. It was cheap and in good condition otherwise. Now I am in the throws of trying to diagnose the problem.
The noise sounds as if it is coming from the engine just below where the head connects to the block. It is loudest up to 2500 rpm then seems to disappear. When I am driving down the road at 2000rpm and take my foot off the gas the noise goes away, but step on the gas and it returns. It even makes noise at idle. The noise seems to get slightly louder as the engine warms up.
From what I have learned so far connecting rods make more noise the faster the engine goes, so it does not seem like it would be the rods. I read on the net somewhere that squirting oil into the cylinder would tell me if it was piston slap-the test seemed to suggest it wasn't. So I was left to believe it may be valve train noise.
I took the cam out and examined the bucket tappets and their "cyliners" and all seemed to be fine. The only thing that looked as if it may be out of sorts were the rubber washers that sit on top of the valves. They were rock hard and very brittle. What the heck do they do? I am going to go get new washers because I can't put the cam back with the old ones...they are toast!
Does anyone have any suggestions as to what my mystery noise might be?
It is not coming from the turbo charger, but sounds like it is coming from the drivers side on the engine block.
Thanks.
If you want to email me directly I can be reached at jboulang@brentwood.sd41.bc.ca