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1981 240D
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24 Posts
Discussion Starter #1
So, I would NOT consider myself a mechanic by any stretch of anyone's imagination, but I "try" to fix/replace "simple" components.

1981 240D 120K miles

Okay, so I changed both my fuel filters with a lot of joy and excitement and it all came to a very disappointing conclusion when she didn't fire again. With that said, I followed Haynes step-by-step and it did not help. Below are the following steps taken during my FAILURE.

1. Removed 2 filters and replaced with new ones
2. Loosened bolt on primary filter and pumped fuel pump to purge fuel lines of any air (fuel was all over the road)
3. Replace 7+ year old battery (because it died when trying to have it fire and it could not hold a charge when trying to jump/recharge it)
4. Removed air filter and sprayed with WD40 (read on forum that this might help, it did not help
5. Now writing this posting.

Please help!
 

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1991 300zx 2+2 @ 129k Miles.
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194 Posts
Please help!
You did not say anywhere anything about the primer pump...Ill return to that in one moment.

When I change the fuel filters, I don't do much with the smaller clear plastic one...Plug it in, and don't worry much.

The larger can fuel filter should be filled with diesel before being installed.

After you have the fuel system plugged back together, you should than get a good pair of rubber gloves, and find the primer pump....Its a round white plastic thing near the small clear plastic filter you just installed.

Turn it counter clockwise until it pulls out. Now slowly pump it in and out until fuel fills the line...and maby sprays out a bit....

Push the primer plunger back into position and screw it back down by turning clockwise until it wont go any more. Just hand tighten it...it does not need to be wrenched on.

See if that helps the starting.
 

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1985 380SE
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1,939 Posts
Open up the injector lines at the injectors and crank the engine for a minute. I put plastic baggies under each line to catch the fuel so it doesn't spill and stink up the garage.

As Whippy said, make sure you fill the big can filter up as much as possible before you try starting.
 

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1981 240D
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24 Posts
Discussion Starter #4
Thanks for the reply.

I primed the hell out of the pump and fuel was actually gushing from both the pump and top of primary filter nut. I did not include in my last posting that at first I was priming the wrong nut/bolt, I was actually purging the smaller bolt to the left of the primary filter. When I re-read Haynes, I purged the right nut/bolt and still nothing.

Also, I know that the primary filter is a screw-on but I only tightened it down by the bolt and did not screw it on. Could this be a factor?
 

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1983 240D Standard
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24 Posts
Ditto Whippy. If you don't fill the can filter it won't start. Last time I changed mine I forgot to have a gas can with me. Had to drive the other car to Shell for $0.20 worth of diesel.
 

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Premium Member
W-1-2-3 Go!
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16,161 Posts
Ditto Whippy. If you don't fill the can filter it won't start. Last time I changed mine I forgot to have a gas can with me. Had to drive the other car to Shell for $0.20 worth of diesel.
A bottle of Diesel Kleen, Diesel Purge or ATF works too. Just top off the filter prior to reinstallation.
 

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1984 300D 375,000 miles 1996 e300d 266,000 miles 1983 300SD 174,000 miles Ascot Grey
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453 Posts
i've been through this too many times, refusing to believe that i needed to purge the system of air. The spin-on filter will fill if you pump it enough, which you have. You need to do as stated above, and crack open each of the five 17mm nuts on the injectors. 1/2 a turn will do. Turn the motor over (10 second or so at a time).You can watch through the window or through the gap between the hood and the cowl... fuel will makes its way from the front injector to the back one. When the rear-most injector weeps fuel, tighten them back. At this point, all air is gone, and you're in good shape.
It saves time to fill the big filter, but the pumping has filled it in your case.
 

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2001 Volvo V40
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2,954 Posts
If you replace the fuel filters, no air will be in the high-pressure area so there is no need to open the hard injector lines at the injectors (IMHO there is never a need to do that, doesn't make a difference at all in how soon the engine starts, it just creates a mess).

If you use the hand pump, do you hear a buzzing sound of the pressure release valve of the high-pressure area opening?
 

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1981 240D
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24 Posts
Discussion Starter #9
OK, so I went out this morning (6am and 24 degrees) and topped off the filter with ATF purged the line again just in case there was any air in the line. Like I said before I am NOT very mechanically inclined, I'd like to be but alas I am not...so, where are the injectors located :confused:?

Thank you all for your written assistance an support, I truly need it!
 

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1984 300D 375,000 miles 1996 e300d 266,000 miles 1983 300SD 174,000 miles Ascot Grey
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453 Posts
i have to do this in one of my cars but not the other. i'm sure it's a result of an imperfection somewhere in the system, but nevertheless, i do have to purge the hard injector lines. I also understand that it should not "have" to be done, but it works for me.
Just try it... it won't hurt. The injector pump has 4 ( 240d, right?) hard metal lines that are clamped together. they are side-by-side on the pump, and go up to each of the four injectors paralell witht he cam cover (valve cover). They should be 17mm.
 

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1981 240D
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24 Posts
Discussion Starter #11
So once I find the location of these injectors all I have to do is unscrew them with a 17mm wrench and "purge" them of air by starting the engine? Is there anything else I need to do besides unscrewing them, any extra precautions I should take?
 

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1984 300D 375,000 miles 1996 e300d 266,000 miles 1983 300SD 174,000 miles Ascot Grey
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453 Posts
here's a photo of somebody doing it with the special tool. You dont' need this (although it would be nice). Just use a regular 17, and find the right "bite" on the nut. The bottom photo shows where they attach to the injector pump. Don't loosen them here, only at th other end. Surpisingly little fuel with come out, although it will be a little mess. Only unscrew them (ccw) half a turn or so. When you get fuel from all four, tighten them and start the car.
At the very least, now you KNOW that fuel is making it to the injectors.
BE SURE to only turn the motor over for a few seconds at a time. The manual says more is safe, but i limit it to 10 seconds. Just a few 10-second tries should accomplish the job.

Google Image Result for http://www.mercedessource.com/files/IMG_8323.jpg
 

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2013 MINI Copper S Clubman, '84 300CD-weekend car
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10,152 Posts
There should not be any fuel coming out from the top fuel filter bolt at all. If the leak is bad enough, this will allow air into the system and give you problems.

You may have the early fuel filter head (look at the part #, if there is an "01" before the last three digits, you have the old style) that has a crush washer. If so and you didn't replace it, I doubt you'll start the engine.
 

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1981 240D
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24 Posts
Discussion Starter #14
Alrighty folks, so these are the steps I took with the unfortunate outcome.

1. Unscrewed the 17mm injector nuts
2. Turned the key and let turn over 5 x at 10 seconds a piece
3. Noticed that only the closest injector was spraying and the other 3 were not doing anything
4. Screwed 17mm injector nuts back into place
5. Turned key and let turn over 3 more times
6. Locked car and walked away from disappointed and :confused:
 

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1984 300D 375,000 miles 1996 e300d 266,000 miles 1983 300SD 174,000 miles Ascot Grey
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453 Posts
well, i probably was erring on the side of caution to avoid adding a burnt-out starter to your woes. It's very possible that you were very near victory. If i were in the same situation, i would perform the same steps, and give it a little more time. If fuel is getting to one injector, i think it will get to the others eventually. An air leak somewhere is probably adding to the issue, and making it harder to prime.
 

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1981 240D
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24 Posts
Discussion Starter #16
End result: Manual fuel pump was broken (cracked) and pushing air into the fuel lines. I had it replaced, purged engine of air and boom goes the dynamite!

Thank you all for your help!!! :)
 

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1982 300D Turbodiesel 212K or so, it doesn't work anymore :-)
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216 Posts
yeah man don't give up on her...i had one heck of time *crappy battery and old starter* getting mine back up and running from the last purge and filter change...after about half an hour i finally got it up and going...

i too was probably on the safe side of not letting it turn over much at a clip...
 

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87 Euro 560 SEL
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480 Posts
How many fuel filters on my 300TD

I bought the stuff needed for a tune up last week and the gal gave me 3 fuel filters, 2 canister and 1 inline. I can only find 1 canister and the inline on my car. Is there a 2nd canister fuel filter on the 300?
 

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1978 W123 300D, 1986 S124 250TD, 1987 W124 300D-T, 1965 W108 250SE, 114 280C, W126 300SDL,W123 300CD
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83 Posts
I bought the stuff needed for a tune up last week and the gal gave me 3 fuel filters, 2 canister and 1 inline. I can only find 1 canister and the inline on my car. Is there a 2nd canister fuel filter on the 300?
Nope. Only one canister (spin on filter) and one inline. The second canister is a spare.
 

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1982 300d 43k original miles with veggie kit
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118 Posts
OK lets talk diesel here this is what I did works great for me I had an old electric diaphragm fuel pump I installed it before the first filter the plastic see through hooked up about 3 ft of cord with 2 clips for the battery cracked the fuel line off the filter and hooked up the pump and in about 10 seconds it was purged then i took off the return line and put it in a old quart oil container and purged it again I did get a lot of air out there

started up hardly any sputter works great only use it when I change filters we have this setup on one of our farm tractors it looses prime over a few days works great there too remember diesel is a closed sealed system #1 enemy is air!!!!!!!!
 
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