Valve Rocker Tapping Noise - PeachParts Mercedes-Benz Forum

carson · #1 10-29-2022, 05:36 PM

I recently noticed a tapping noise coming from my OM617 at certain RPMs and tracked it down to the valve rockers. You make a loud metallic tap when wiggling the rocker between the cap nut and the cam lobe - specifically on the exhaust valves. I double checked the clearance and they are spot on at 0.35mm (just talking exhaust since intake clearance is too small to make this noise). Is it normal for the rockers to make this noise with the factory suggested clearance? Does anyone else hear that noice when their engine is at certain RPMs?

Here's a video demonstrating what I'm talking about. I'm curious to know your thoughts and suggestions.

https://www.youtube.com/watch?v=dD8kRzXzjVs

Diesel911 · #2 10-30-2022, 12:52 AM

It has been so long since I have handled mine I cannot say and right now my cylinder head is off of the engine.

You might pick the nosiest one and rotate the engine a few times by hand and re-check the clearance and do that several times and see if the Clearnce is always the same.

In a obscure thread one of our members said that depending on the position of the valve rotator you can think your Clerence was correct but after the engine is rotated and the valve rotates to a different position your clearances is off.

When I wire the throttle lever in the shut off position and use a remote starter and crank the engine with that. I adjust the valves. Crank the engine some and recheck the adjustment. All I can say is that during the recheck I occasionally find one that is has more Clearnce compared to the first adjustment.

I don't know if I made an error, or it is as the other member said an issue with the valve adjuster.

So, I crank some and re-check some till I am satisfied.

I had a meatalic sound from under the valve cover and I found that it was that upper sheet meatal timing chain guild that was loose.

Or it could be something else making the noise. The air filter housing if you have a federal type, one is notorious for making noise and it does that at different speeds.

Good luck.