30,000k without an oil change? Yikes!

Check the chain tensioner -- pull the right valve cover gasket and see if you can push the curved rail back towards the fender easily. If so, get a new tensioner pronto, as a slapping chain will break the upper (plastic) chain guide, and that usually causes the chain to break.

Chances are that the lifters are shot from crap in the oil. Hard sludge builds up terribly in the lifter gallery on this engine if dino oil isn't changed often enough.

Full synthetic oil will usually remove the sludge and clear the lifters after a while, but if you change, change the oil filter at 1000 miles and 2000 miles with a top-up for the oil (no need to change the oil) to get the slops out of the engine. The filter will plug very quickly.

If the noise is definitely associated with the valves AND you can see oil running out of the oil tube onto the cam through the oil filler, synthetic will probably fix you all up.

Otherwise, you need to check the oil pressure and oil delivery at the cam -- if you have poor oil delivery, it's probably cam time, low oil pressure means change the filter, and if that doesn't help, you need to investiage the cause.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!