Basically, when idling, there is clacking sound coming from under the valve covers. I took it to an independent MB mechanic. He recommended replacing the rockers. When I saw the price, I asked him if there were alternatives. He said he had a some used rockers he could put on, that were in good shape. The used rockers were put on, but there is still this clacking noise, so now he is recommending new rockers and new cam shafts. He said the cam shafts have flattened a little, but I could probably continue driving it for another year before making the changes recommended.
Why are you recommending?
1989 420 SEL