Hi, April 22, 2012
I have a 1967 Mercedes 250S with 99,000 miles, purchased new in 1967 by my father.
I recently replaced the timing chain. I also took out and re-installed the chain tensioner using the published bleeding procedure of pouring oil into the little reservoir at the chain tensioner in the head and at the same time pumping the sprocket up and down.
I got a rattling noise part of the time with the engine running. No noise when the engine was under load. I took the valve cover off and there was slack in the chain. I took
channel lock pliers and pulled the sprocket up to tighten the chain. When I pushed down on the sprocket with a screwdriver, there was about 1/16 to 1/8 inch free play in the sprocket movement. Anyway, I couldn't eliminate the rattle.
I thought the chain tensioner might be worn out (it was not leaking) so I bought and installed a brand new "LASO" chain tensioner. The new tensioner had a bit more resistance than the old tensioner when I pushed the piston in with my finger.
I was careful to follow the bleeding procedure when installing the new tensioner. I had someone else pour oil slowly into the reservoir through a funnel and tube while I slowly pumped the sprocket back and forth. It didn't react like the literature said it should. I got bubbles in the reservoir but it never did really harden up. I continued to have about
1/16 to 1/8 inch freeplay in the sprocket movement.
When running the engine, I still have the same problem, with rattling of the chain part of the time.
I took the valve cover off and there was slack in the chain. Using channel lock pliers, I was able to pull the sprocket up to tighten the chain and it stayed tight. I still had about 1/8 to 1/16" freeplay when I push the sprocket down with a screwdriver.
I again started the engine and drove the car. Same as before, no noise when accelerating or when the engine is under load but noise when coasting or idling.
I hope someone can give me some advice.