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1984 300dt 400000km, 1985 300dt 194000km, 2005 golf tdi 112000km, 2005 odyssey(wife's van)
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207 Posts
Discussion Starter #1
wow, unbelievable. i replaced both fuel filters in my 84 300dt. I then went to crank her.. no way..
did not want to start. took me 1/2 hour to get her going. battery died, had to hook her up to my wifes odyssey for another 1/2 hour. finally i unscrewed the primer and pumped and pumped and pumped.. did not want to start.. re primed and again tried to start. all she did was crank crank crank... finally 1/2 hr later got her going...
well the next time i will know what to do..
 

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1984 300D
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5,065 Posts
wow, unbelievable. i replaced both fuel filters in my 84 300dt. I then went to crank her.. no way..
did not want to start. took me 1/2 hour to get her going. battery died, had to hook her up to my wifes odyssey for another 1/2 hour. finally i unscrewed the primer and pumped and pumped and pumped.. did not want to start.. re primed and again tried to start. all she did was crank crank crank... finally 1/2 hr later got her going...
well the next time i will know what to do..

For others that this happens to: If you reach the point where you believe it is not going to start you have Air trapped between the Fuel Injection Pump and the Injectors.
The remedy is to loosen the Fuel Injection Hard Line Tubing’s Nuts at the Injectors and crank the Engine until you see fuel coming out from under the Fuel Injection Line Nuts. Tighten the Nuts and attempt to start.

To reduce the chance of Air getting trapped in the Fuel Injection Hard Lines you can pre-fill the new Spin-on Fuel Filter with Diesel Fuel followed by pumping on the Hand Primer until you hear sort of a squishing or buzzing sound coming from the Fuel Injection Pump. And, after that pump some more with the Hand Primer to be sure.

Or, you can put the Spin-on Filter on without filling it with Fuel and do a lot more pumping with the Hand Primer until you hear that squishing or buzzing sound coming from the Fuel Injection Pump. And, after that Pump a lot more to be sure.

You need to know how to bleed the Air out of the Fuel Injection Hard Lines incase you run out of Fuel. If you run completely out of Fuel and add Fuel to the Tank there is going to be a whole bunch of Air in the system.
You would do the same thing with the Hand Primer and listen for the same sound but this time you would also have to loosen the Fuel Injection Hard Line Nuts at the Injectors also and follow the Instructions in the 2nd paragraph.
 

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1985 300CD Turbo coupe, 2006 E320 CDI sedan
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573 Posts
well the next time i will know what to do..
Hopefully that will include filling the new spin-on filter with fuel before installing it. I do the inline filter first, gravity fills it just fine. But when I move to the spin-on, I have the new (full) one within arm's reach. Have an old towel or dry rag handy. Spin the old one off as fast as possible. Drop it into a pail or something so that you can get the new one spun on as fast as possible. After that - soon as I get the diesel wiped off my hands that is - the car starts right up. No undue cranking at all.

//greg//
 

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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
as well as what has already been mentioned, you should replace that primer pump with the new black bosch pump. Cheap, and super-easy to install. It doesn't unscrew... you just put your hand on it and pump. Seems like every one of the white plastic pumps i have seen leaks, and will let air in the system when you're trying to prime. it can be very frustrating.
 

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1984 300dt 400000km, 1985 300dt 194000km, 2005 golf tdi 112000km, 2005 odyssey(wife's van)
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207 Posts
Discussion Starter #5
thanks a lot guys. very helpful. :bowdown:
once i removed the fuel filter off, i poured the fuel from the old filter into the new filter, but did not quiet fill it. next time i will have fresh fuel standing by.
where can i get that black bosch primer?

1984 300dt
1985 300dt
 

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1984 300dt 400000km, 1985 300dt 194000km, 2005 golf tdi 112000km, 2005 odyssey(wife's van)
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207 Posts
Discussion Starter #6 (Edited)
thanks a lot guys. very helpful. :bowdown:
once i removed the fuel filter off, i poured the fuel from the old filter into the new filter, but did not quiet fill it. next time i will have fresh fuel standing by.
where can i get that black bosch primer?

i found this one on line, not sure if its correct??
I have to check still, but i did not notice if i can apply a wrench to the white pump.

Fuel System
Product 31/3
Primer Pump, New Style - BOSCH
$22.50
New style diesel primer pump used on diesel UNIMOGs and diesel Gwagens.

Made by BOSCH, an OEM to Mercedes-Benz.

Shipping Weight: 0.2lbs
Manufactured by: BOSCH


1984 300dt
1985 300dt
 

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1984 300D 375,000 miles 1996 e300d 266,000 miles 1983 300SD 174,000 miles Ascot Grey
Joined
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453 Posts
that's the one. sure looks nice compared to the old white plastic. It's one of those gratifying jobs... easy, quick, cheap, and you are rewarded every time you use it. When i changed the pump on my 1984, i managed to use a regular 17mm wrench. When i did my 81, for some reason, i just couldn't get to it, and had to borrow a 17mm crow foot wrench (which i later bought). Just fyi, it might be necessary.
btw, even cheaper at autohaus...

Your Parts Search Returned 1 Part(s)
 

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2013 MINI Copper S Clubman, '84 300CD-weekend car
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Please use any CLEAN fuel, instead of what's in the old filter.

Kerosene is fine, I keep some Diesel Kleen around for just this purpose. A fuel injector cleaner works well also.
 

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1985 300CD Turbo coupe, 2006 E320 CDI sedan
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573 Posts
Kerosene is fine, I keep some Diesel Kleen around for just this purpose. A fuel injector cleaner works well also.
Excellent suggestion! Sounds like a much less complicated way to use that can of Diesel Purge that's been sittin' on my workbench.

//greg//
 

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1984 300dt 400000km, 1985 300dt 194000km, 2005 golf tdi 112000km, 2005 odyssey(wife's van)
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207 Posts
Discussion Starter #11
Please use any CLEAN fuel, instead of what's in the old filter.

Kerosene is fine, I keep some Diesel Kleen around for just this purpose. A fuel injector cleaner works well also.
clean fuel next time, for sure.
thanks.
btw, any thoughts on the monark fuel primer pump??
 

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1981 MBZ 240D 4-speed
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51 Posts
I've seen a recommendation at Mercedessource for the Monark pump instead of the Bosch for users of biodiesel or WVO. Anyone know why, or have experience with that?
 

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1984 300D
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5,065 Posts
I've seen a recommendation at Mercedessource for the Monark pump instead of the Bosch for users of biodiesel or WVO. Anyone know why, or have experience with that?
You can believe what you want concerning Mercedessourses marketing but, Bosch claims their Hand Primers have Viton Seals inside. It is well known that Viton is preffered for Fuel Hoses when using biodiesel or WVO.

Bosch Hand Primer has Dual edge Viton® seal:
Hand Primers
 
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