I noticed pinging at around 55-65 mph. This is the first I've heard this. Valves were adjusted around 10k miles ago. All filters fairly new. Could I have a batch of bad diesel? Or could it be something else? Opinions? Thanks

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85 300TDT 456,000 orig. miles

Knocking? Try a can or two of diesel purge. I hope it was a gradual thing rather than just all of the sudden.

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Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k

thanks, I'll try that. It doesn't sound like a knock, and is not constant. It is very intermittint.

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85 300TDT 456,000 orig. miles

I can't tell if its been gradual. I usually drive with the stereo pretty loud.

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85 300TDT 456,000 orig. miles

shear2001,

If this is something you have even under hard throttle, it may be a bad injector, but if it is a sound that only occurs when you are going light on the throttle and sounds like a popping rattling noise, it is probably a noise that can be cured with an additive. Some Diesel fuel is not as good as other Diesel fuel and it will cause deposits to build up on the critical surfaces of the injector nozzles. At some point these deposits can interfere with the spray pattern and closing of the injector nozzle, leading to this kind of pinging, popping and rattling sound.

Do a search on Diesel fuel additives to get a list of many available across the country. Someone once took photos of the labels and posted them. I use RedLine Diesel Fuel Catalyst, and have for about twenty years now. I also use PowerService now and then. But nearly any of them will cure this very common problem, if it is cureable with an additive (at least I know the Redline product will, usually within a few tens of miles of driving after putting it in). I use them (the additives) regularly, with every fill up and never hear the annoying noise anymore.

Good luck and I hope this helps, Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

Jim, thanks for your i post. I'll give it a try..

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85 300TDT 456,000 orig. miles

I feel stupid. I found the problem, it was the alternator screw rubbing against the pully. It had apparantly loosened. Sounded just like injector problems. Thanks all for your help.

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85 300TDT 456,000 orig. miles

BOY OH BOY OH BOY..... do I hope my nailing problem turns out to be something simple like that!!!!

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"Know other lessons I need to learn? TELL me. Tired of learning'em the hard way".

Glow Plug Wait: [i} Time of silence in homage Rudolph Diesel. Longer you own a diesel. more honor you give". [/i]

Life; SNAFU Situation Normal All Fouled Up, & FUBAR: Fouled Up Beyond All Repair

-Now: Snafued Jeep TJ w/OM617 2Be daily driver & building SS M1079 w/Ambo boxed /live in Adv. Truck, Diesel KLR conversion
-Sold 62 UNIMOG Camper w/617 Turbo, 85 300SD