I changed the fuel filters. I guess about 1 litre of fuel must have spilled when changing the clear filter. I had very little spill when changing the big fuel filter.

Is there a constant pressure for the fuel to flow or am I having pressure building up in my gas tank.

If so how do I relieve the pressure and where is this located ?

I also changed the last fuel return line with a plug on Injector No. 5. I reckon about one coffee cup of diesel must have spilled out. I did not encounter this when changing the other return lines at the injectors.

What could have caused this ?

Thanks for ur input.

Anyone ?

I don't know the fuel tank arrangement of a W124. Wtih a W126, parking downhill with a full tank means a good rush of fuel when you remove the small filter. I suppose the pump serves as something of a block so there is limited flow to the big filter.

Completely guessing - if the IP is in the position of firing the #5 injector then when you remove the return hose you'll get the fuel for #5 pumped out through residual pressure. For my part I left the #1 injector line off the injector while working on something and made a heck of a mess. The other lines didn't have anywhere near the flow.

Sixto
95 S420
87 300SDL

sixto's first paragraph is right on. if parked nose down like in my dw the fuel will run out from gravity, usually. just loosen the clamps and have the new filter ready to slip on immediately. loosenn the engine end and lift the line up. then take out the old filter and put your finger over the end of the line. then put the new filter in the tank line and slip it into the engine side of the line with the clamps loose. at this point you wont leak much. and just tighten the clamps now.

sixto's secod paragraph seems unlikely to me.. a few drops yes but not a quart.

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.