i recently replaced the head on my 300TD. i wanted to do some cold compression testing before i completed the rebuild to check if the cylinders held pressure. then when i cranked the engine i heard a pinging from the engine. it came in rhythm about once every two seconds.

my first thought on the source is valves are hitting the pistons. mabey the timing could be off by one or two links on the chain.

but in order to check i have to remove the whole cam shaft and tapets.

don't really want to do that, so if there is any other source that this pinging could be coming from, anything more serious, or less serious.

ill try to post a video of the sound if i can find my camera.

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Current
2006 E320 CDI, 57K bought at 67K "Liesl"
1986 190E 2.3-16, 198K bought at 56K "Brigitta"
1987 300TD (Chuggin Along), 292K "Friedrich"
1995 E320 Wagon, 200K "Louisa"

Past
1987 300SDL, (sold) 125K, bought for 1$ "Kurt"

Pull the valve cover and turn the engine by hand until the cam and tower marks are aligned. If you meet any resistance, stop turning the engine! If you're able to align the cam marks, check the crank pulley reading against the pointer. Hopefully it's right at TDC or a couple of degrees away. If cam timing is correct, I don't know what the sound could be.

If you meet resistance, remove the cam, turn the engine very carefully keeping tension on the chain along the way. There's a special tool for this but it should be safe to use your hands to hold the chain if turn the engine very slooowly.

Sixto
87 300D

Vac pump or belt driven items could be source of noise. The pre-chamber has to be shimmed when the head is cut. Maybe it can hit the piston if not done correctly. Another member reported noise from the timing device on the injection pump.