1999 E300 Diesel W210 - Help!

The story so far . . . The car was starting to get sluggish under acceleration, so I decided to change the fuel filters. I changed the pre filter and after some cranking it came to life fine. Then I changed the main filter and it will not start at all, after a tremendous amount of cranking. After a few minutes of cranking is coughed but that has been it. I have changed the filters before and know it takes a mess ‘o’ cranking to get the air out. I have about a third of a tank and have jacked up the rear to try to encourage fuel flow.

I used my hand vac pump to make sure fuel was getting to the engine compartment and then thru the filters. I got flow at both places so it seems the lines and filter are o.k. I was also able to blow air thru the return line. I then cracked the nut where the first injector enters the engine and nothing came out while cranking.

Important bit -
My next experiment was to put the line from the lift pump straight into a cup of diesel, much cranking and still nada. This does not seem good, but all I did was change the fuel filter.

Diagnostics are just not my area of expertise but could the fuel pump be shot, even though I only messed with the filter??

Thanks for any help!
george

Charge the battery while you reconnect the lift pump line and have dinner; then crank for 30 secs. next remove both the Pre filter and the main filter and prefill both with fuel.

Crank some more. If it *coughs* while you are cranking keep cranking until you are 100% certain it is running. It won't hurt the starter to hold the key for an extra sec or two. Is counter intuitive but if you let up you start the whole process again.

You didn't throw the prefilter oring away when you changed it did you? The one hidden under the rim???

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

Be sure to crack 2 or 3 of the injector lines at the injector and crank until you see solid streams of fuel, then re-tighten and then try to start. If it still doesn't start, repeat the process on any injectors you haven't already bled.

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I choose to be happy, even when the Mercedes is being awkward, lol

when I replaced my filters I filled the main filter with a funnel after I had it in place before I bolted it up. Started up normally as though nothing was done.

Good luck

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1999 Mercedes E300TD daily driver sold at 238K miles 106K miles were mine, rust worm got it :-(
2006 Mercedes CDI new daily driver! 56,000 miles May 2016 now 85,625 Apr 2018 and Apr 2019 101,000 miles Apr 2020 109,875. March 2024 135,250

Thanks for the help. I have been trying to start the car off and on all day, with charging inbetween, each time with at least 30 seconds of starter a couple times in a row. If the problem was air in the filter, wouldn't my attempt with a line straight to the pump from a cup of fuel allow it to start? Not sure about that. The filter was filled up when I installed it.

I can try cracking all the injectors tomorrow.

Thanks again everybody

It's not completely out of the question that the initial symptoms were caused by a failing lift pump. Check to see how it is pumping.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

The best advice I have seen so far is to loosen the Fuel Injection Hard Lines at the Injectors and crank until you see Fuel coming out.
When Air gets into the Hard Line it is trapped between the Fuel Injector and the Fuel Injection pump. Cranking compresses the Air in the Hard Lines and it does not want to move much and takes for ever to pass through the Injector.
Loosening the Injector Hard Line nuts provides an escape route for uncompressed Air to get out.

I also think the idea that the original symptoms could have been caused by the Fuel Supply/Lift Pump is reasonable (also possible plugged Tank Screen; Fuel Pressure Relief/Over Flow Valve not holding pressure?).

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84 300D, 82 Volvo 244Gl Diesel

Yep, next step is a flow test on the lift pump. She may be dying. Pull the pipe off the lift pump and crank with a container to catch the fuel. It should fill a coffee cup in no time.

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I choose to be happy, even when the Mercedes is being awkward, lol

When doing lots of cranking, I prefer to do a minute or two, then take a break and let the starter cool a few minute while topping the battery up with a charger.

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I choose to be happy, even when the Mercedes is being awkward, lol

I didn't see an answer to this. I'd put my money on o-ring.

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Mark in MA
05 MB E320CDI 402k Granite Grey Metallic
05 MB E320CDI 267k Black
05 MB E320CDI 232k White
05 MB E320CDI 209k Tectite Grey
99 Dodge 2500 Cummins 5sp 148k
62 Jeep CJ-6 120k

I'll second the suggestion that you crack the injector lines loose at the injector end of the hard lines until you see fuel flow.

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'93 190E/D 2.5 Turbodiesel 5-speed (daily driver)
'87 190D 2.5 Turbo rustbucket - parts car
'84 Dodge Rampage diesel - Land Speed Record Holder
'13 Ram 2500 Diesel
'05 Toyota 4Runner

That is exactly my practice too, it starts as nothing was ever disturbed.

Yep; either that or a bad oring or connection elsewhere on the suction side of the lift pump. OP did say he had loosened one of the lift pump connections which means all suction peviously gained by cranking was lost. Concentrate on #1-4. http://bp3.blogger.com/_p71v9ofBM6w/R5ZR4hrNUFI/AAAAAAAAAIQ/XCBQ40qtPDQ/s1600-h/fuelflow.JPG

So....did you purchase a separate prefilter oring (the size of a quarter) for the new prefilter, or did you reinstall the old one? We belabor the point because you wouldn't be the first person who threw one away and had to go dumpster diving to get their car running again.

Follow the fuel path and note where air first appears while the system is priming. Your leak precedes that point.

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

Maybe a link to my neophite prefilter days will sound familiar:

http://www.peachparts.com/shopforum/showthread.php?t=207371

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Mark in MA
05 MB E320CDI 402k Granite Grey Metallic
05 MB E320CDI 267k Black
05 MB E320CDI 232k White
05 MB E320CDI 209k Tectite Grey
99 Dodge 2500 Cummins 5sp 148k
62 Jeep CJ-6 120k

Sorry for the delay in getting back online and thanks for the ideas.

I did replace the o ring on the pre-filter as well as the two on the banjo bolt. I'll be cracking the injectors tomorrow. And hope for the best.

I have a set of o rings to replace but had been putting the project off. Would prefer to get it back on the road and then put it in dry dock for that as I will also be replacing the motor mounts and various other things (maybe even the lift pump!). BTW it was also taking an extra second to shut down (also part of the upcoming project), maybe its a combo of things not allowing enough suction?

Thanks again