1980 240d making pinging rattling noise
 

hello i`m hoping someone may be able to help me with this problem. i`ve done a search and didn`t find anyone with the same problem. my car is making a pinging noise at high rpm`s almost like a gas preignition sound. it seams to go a way when the car is warm sometimes it won`t make the noise at all. it always makes the noise if the car has been sitting over night. i adjusted the valves but it`s still there. i tried cracking the line to each injector one at a time to isolate it to one cylinder but it didn`t seam to make a difference. any idea`s would be greatly appreciated thank`s

pinging diesel
 

There are two different sounds possilbe--one is caused by the piston top hitting on deposits in the combustion chanber--running a can of TECHRON in the fuel tank will remove lots of the deposits.

Other cause is 'nailing' which is caused by poor spray pattern on the fuel injector, very poor fuel quality (low cetane number), low compression, or injection timing too advanced. 'Nailing' is what happend when a lot of fuel gets injected before any of it starts burning. Defective glow plugs can cause it too. Anything that interfers with the injector putting out a fine fog of fuel will cause the nailing. There is a good injector cleaner on this web site (1pint can) that will usually clean up mildly fouled injectors.

Bad chain tensioner is allowing the chain to slap on the guides. It can get so bad with a worn chain that the chain will "fly" off the cam sproket and tap on the valve cover (at which point it usually also jumps).

Check the wear (stretch) on the chain (do a search!) and if worn, replace chain, tensioner, and the tensioner guide if it has slots worn in it.

Peter