Hello. I have been having this strange issue that I cant solve on my own. On my 1984 300TD the fuel hose that returns the fuel from injectors back to the system keeps rupturing at injector 1 (one closer to the front of the car). I keep replacing them, but after driving for a little bit, and especially at high speed it busts again and while my wife was driving behind me, she noticed a mist of diesel fuel on her windshield... Do I have a clogged return line or injector? I dont even know where to look... Also if it has anything to do with it, when its cold outside the car has a very hard time starting and runs sporadically untill it warms up.. (it did not used to do this). Thanks

Are you using actual MB fuel line ?
I think it is a gray with orange strip on it (?)

__________________
1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

Sounds like a blockage somewhere, since it's the first one, that's the one that goes to the fuel filter housing, I believe, might try a few psi (4 or 5 max) to see if it's blocked, when you find out that it's blocked, find the blockage, could be at the tank.

__________________
Closing the store
Benzbonz.biz on your smart phone or tablet.

Do you have a cigar hose from the fuel filter to the steel return line or is it a normal straight hose? The cigar hose allow the pulsing from the fuel system to be absorbed where as a straight hose does not and can cause funny sounds and could be restricting the return flow when it pulses and making the weakest point to pop loose.

__________________

Of course look for a blockage but the above in red sounds very abnormal. I am trying to figure out from that statement how the Fuel could be under enough pressure to make it out of the Engine Compartment and into the Air outside of the Car.

If you know; how many miles are on the Injectors and the Engine?
Are you burning only Diesel Fuel.

A Wild Guess is there is combustion pressure coming up into the Injector.
I have never done this type of test before but I believe if you remove the Fuel Injection Hard Line and the Fuel Return Hoses; hold down the Manual Shutoff and crank the Engine; if there is a Compression pressure leak you maybe would see some Fuel bubble/come out of the Injector Fuel Inlet or Fuel Return nipples.
The compression pressure is not the same as the Combustion pressure but you might see something or Hear some hissing or other sound if it is leaking.
You also might try swapping the #1 Injector with one from the other end of the engine and see if the problem follows the #1 Injector.
While the 2 Injectors are out of the Engine inspect the Heat Shields and the Tips of the Injector to see if they have any erosion from burning.

__________________
84 300D, 82 Volvo 244Gl Diesel

Purge with the Lubro Molly and replace the filters. That's the cheapest way to move forward.

It does sound like blockage.

So diesel fuel leaks and the droplets atomize and then collect on the windscreen of the following car, sounds reasonable to me.

My W126 had a bad delivery valve leak(s) and fuel would run out, pooling on top of the motor mount infact, the under side of the car was coated with fuel as was the back of the car. MY WIFE WAS ALSO FOLLOWING behind me and complained that it smelled like fuel, and the windscreen was coated with an oily substance. (Diesel fuel).


Try blowing each of the lines out. remove the banjo on the filter housing and make sure it is clean and clear, Check each of the hoses (Down stream), then blow back to the tank and listen at the fuel fill cap for gurgling.

Use a rubber tipped blow gun and a source of compressed air. Everyone should have an inexpensive air compressor, or access to one. I just went through this with the W124 (chasing what I thought was a clogged line) I fixed a couple minor leaks, replaced the fuel filters, bang, good as new and bobs your uncle.

__________________
85 300D 3 pedal. Current project.
83 300TD (need rear wiper assembly dead or alive)
84 300SD Daily driver
85 300TD almost 400k miles and driven daily.
98 E300D *sold
86 300SDL *sold and made flawless 10 hour journey to new home.

thanks for all the advice, i will look for the blockage in the return lines this weekend.. The reason there was fuel in the air behind the car is that the leak became pretty big while driving on the hwy and after I parked the car there was a small pool of fuel on the grond (and yes I only use diesel fuel and the engine has over 250k miles on it)

First thing I would do is pull the cigar hose from the metal fuel line and stick it in a bottle and start the engine. See how much fuel is flowing out of it at what kind of pressure. Maybe even take a video of it, post in on YouTube and link it here. There should be a fair amount of volume and flow coming out of that hose.

__________________
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

Thanks for more info. I did not beilieve it was possible for that to happen.

__________________
84 300D, 82 Volvo 244Gl Diesel

Well, today I did pull the hose (I do not have a cigar hose, but a straight one) off the metal fuel line.. started the engine and by the time i wen back to look at it, it filled about 1/2" of the 3" diameter jar.. and by the time I went back to turn engine off, there was over 1" of diesel fuel in it.
So as I figured there is no blocakge in that line. Where should I look next? I was planning to put air hose in the metal line and blow some air in, and listen if it bubbles in the tank....? or should I be looking/doing something else? Thanks

My recollection of the last time I did a diesel purge was that there was a violent pulse of diesel coming out of that return hose. So based on that sketchy memory, I'd say there's a blockage.

__________________
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

Ok, where should I be looking for the blockage? Between the cigar hose and fuel tank, or between injectors or cigar hose? It there an easy way tp clear the blocakage? Just blow it out with air hose or? Thanks

Quite simply, EVERY WHERE.

If the same hose is popping off, and a 'blockage' is to blame, then check everything down stream of that point. There isnt much.

Three connections on the return banjo on the filter, a hose to the hard line (cigar), the hard line to the rear, a rubber hose to the tank.

Pull the hose off the banjo that goes to the tank hard line, remove the fuel fill cap, blow air and listen at the filler.

__________________
85 300D 3 pedal. Current project.
83 300TD (need rear wiper assembly dead or alive)
84 300SD Daily driver
85 300TD almost 400k miles and driven daily.
98 E300D *sold
86 300SDL *sold and made flawless 10 hour journey to new home.

As I stated before about the cigar hose, put the right hose on and see what happens. You state that you have a regular hose. That hose can pulse a lot enough that it can make the hose visible pulse.

Also try blowing some air through the return steel line. Make sure to take the fuel cap off though, you don't want to inflate the tank.

__________________