Should this little part have any signs of chain contact?
First pic is for orientation. Second pic is a close up, of course. It appears to be some type of pin. There is a threaded hole for a vacuum pump bolt to go through on the front of the timing cover in that same spot. I have been searching for the source of an intermittent "clack" at the front of the engine. It's not the belt tensioner or any of the accessory pulleys. I've run it without the belt to verify.

The timing chain tensioner seems weak in that it takes very little pressure to push it in. The engine is very noisy until oil pressure pops up. It doesn't sound like rods. It's not steady. I've been tossing around the idea that my timing chain is the source of the "clack". I don't see how the chain could be rubbing that pin looking thing without it levitating off the fuel pump sprocket. While the picture doesn't show the marking there is definitely one there. Maybe I'm just looking at it wrong.

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Inside the cam/valve cover

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You need a new tensioner. How many miles are on it?

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Jim

If the chain is hitting something then the noise will be steady and pitch may increase with engine speed. Otherwise it is not the chain IMO.

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

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225k
Would the tensioner cause worn places on the cam/valve cover?

The tensioner can allow the slack that can cause the wear.

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Jim

Thanks! Great to hear from you.

I'd say you've found the source of the noise.

Replace the timing chain tensioner, but please also inspect the teeth on the camshaft sprocket for wear. If the chain has been moving around that much, you may have a sprocket or two or three to replace.

How is the timing chain stretch?

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Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

If I carefully line up the cam marks, and I do mean carefully, I see 2* BTDC.

I really appreciate everyone's reply in trying to help me.

I like to lay a ruler along all the camshaft bearing caps, they all have the same mark, and hang the ruler end over the gear shoulder so you can look directly down, one eye only please to avoid parallax error, and then slowly crank at the crankshaft nut until the marks are lined up.

If your 2 deg BTDC is correct, then either your method is off, the pointer at the crankshaft balancer is wrong, or the chain is REALLY wrong (stretched and jumped forward?).

Something is wrong, just need to determine what that is.

Someone posted a method of finding TDC by removing the injector, adding a clear tube sealed into the hole left by the injector, and filling the cylinder and prechamber with oil so it is up into the tube. Slowly rotate engine clockwise until the oil stops rising in the tube, and you are at TDC. Verify the pointer is at TDC or calibrate it now by setting it to TDC.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

I'm gonna say that my method or the chain is the problem. I'll go check it again. And again. And maybe again. I wouldn't doubt that the cam sprocket is pretty worn. I'll keep digging.