Knocking noise? Possibilities?

[86560SEL]

I have mentioned this before, (keying in on other topics) with no response. I was hoping that by no response that I had nothing to worry about, but it is concerning me, so I will try again with this totally separate thread.

Anyway, I have a W126, with 264K miles. The car still has good power and does not use oil or smoke from the exhaust.

I do however have the common lifter clacking from the passenger side- which from what I gather is not that uncommon. I am guessing that the cam is worn on that side, considering the mileage. To address this (aside from installing a new cam), is there any additives I can add to the oil (such as Slick 50) to cut down on the wear to make it last longer? I have not priced a new cam, but I am sure it is more than the car is worth.

Now, on to more serious woes? I have a faint knocking noise (or what I think is knocking) when I accelerate from a stop. I can hear it from about 1000 rpms up to about 2000 rpms and only when in 1st gear. I cannot hear it while driving, after it shifts to 2nd, or even idling. I am hoping and praying that it is not a rod bearing or something. It may be the cam causing it? It has not seemed to have gotten any worse since I have owned it. If it is the cam causing the knock, about how many more miles can I expect before it quits running?

I know that my 69' Caprice had a engine knock and it was the cam causing it. We put in a new camshaft and the knock was gone. We also put in new bearings.


If it is the cam and I continue driving, will it quickly ruin the engine? I always drive the car easily- I have not even had it over 3000 rpms, so I hope this helps some. This is really discouraging, because from what I have been able to gather here, knocking is very uncommon on the V8 Mercedes and when I did a search, I do not see anyone with a W126 complaining of a knock- so this is surprising. My car appears to never have been abused.

This is a old car and I really do not want to spend a lot of money on it (such as a $$$$ rebuild), as I can buy another car cheaper, but I really like this car. It still has excellent interior, still drives and rides good and runs smoothly and still has no leaks (knock on wood). Also, the transmission also has no problems- perhaps it was rebuilt before? All of the shifts are smooth, but firm, as they should be. Also, it still has a good, rust and dent free body, except for that rust on the door bottoms due to plugged drains and that slight surface rust problem on the upper part of the trunk below the window.

I only paid $1000 for it, so I will probably just drive it until it hits the road, then haul it to the salvage lot.

Thanks for any input.