In my '76 300D I have noticed a bit more nailing, on idle lately, so I replaced the return lines hoping that I might have a small leak. I replaced all the lines except the plug on the last injector; I will have to do it later when I get one. Anyway, she is still nailing a bit and still a bit noisy on idle compared to when I got her a few months ago.

What else could be causing the excessive noise? Injectors firing early?

-Scott


Had to edit the poor diesel terminology... nailing not pinging.

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1979 240d 177k Sold
1976 300d ~220k daily driver For Sale
1977 450slc Sold

300d4me

I don't think leaking return lines would cause nailing, I would run a can or two of Molly Purge through then find a hill and do an Italian tune up. Use the search as you will find plenty on nailing, its a common thing, Do you do allot of city driving?

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

Make sure your vacuum pump diaphram is not defective, letting excessive oil get into the intake manifold. Remove the line going from vacuum pump to intake manifold and make sure no black engine oil in line or at fitting on vacuum pump----black oil means leaking diaphram. If diaphram leaks bad enough, you will also notice "hard" brakes and more smoke than usual from exhaust.

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K. Weimer
300SD (1)
300D (5) [Plus 1 parts]
300SEL 4.5 (2)
280SE (4)
280 (2)
250 (1)
250SE (1)
240D (7) [Plus 1 parts]
220D (11) [Plus 3 parts]
200D (2) [Plus 1 parts]
180c (with sunroof)

1995 Nissan UD1800 rollback
"If I can't fix it, it don't get fixed"

300d4me,

My 1975 240D was very susceptible to poor quality fuel and it was while driving that car that I was introduced to RedLine Diesel Fuel Catalyst. Made the "nailing" and clatter at low power/very slight throttle position while coasting or backing off go away. Try the Moly Diesel Purge stuff, and then use an additive with every fill up to make up for some of the poor quality fuel you run into. Should help, and if you are lucky like I was, makes the problem go away. Good luck, 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)

I generally put in an additive with every fill, either Redline or Lubro Molly, depending on the feeling of the day. I have a can of Molly Purge and I will have to see if I can run it through this weekend. I am assuming that an Italian tune up entails a lead foot up the hill?

I do a lot of city driving compared to the highway travel I do.

I think I read some ware that injectors need to be replaced or rebuilt every 100k or so. Is that correct? I am about to start breaking her in, I should turn 200k real soon. I think the article I read blamed the majority of nailing during idle on wore injectors.

-Scott

__________________
1979 240d 177k Sold
1976 300d ~220k daily driver For Sale
1977 450slc Sold

300d4me

I think you have a good chance of clearing up your problem with the Italian tune up and Molley Purge but it may take a while. I put new nozzels on my injectors for about $25.00 ea, its a no brainer job and I figure I will clean the old ones and keep them for spairs. 100K sounds reasonable to me although how you drive and the quality of fuel makes a big differance.

Ya, you got it "lead foot up the hill" Load the engine good but dont lug it .

Steve