fuel leak around injection nozzle - PeachParts Mercedes-Benz Forum

#1 09-19-2007, 01:32 PM

1992 300D 2.5 diesel. #1 & #2 injection nozzle fuel runs down cylinder head. The small hose from #1 to #5 are dry and are new. Some times a lot of fuel leaks out and but most of the time a few drops on the ground. Are there o rings on the injection nozzle and if so, how do I replace them? I was told the prechamber maybe cracked. I need help.
Thank you for any information you can provide.

benz11

TMAllison · #2 09-19-2007, 02:22 PM

Warm it up and then spray the inj down with brake cleaner to get it clean and dry. Then fire it up and feel for fuel where the two halves of the inj thread together. More than likely is from there or from the nipples and return lines above that.

pmari · #3 09-19-2007, 02:26 PM

Are you actually seeing fuel on the injector it's self? I'd give it a good wash down and see exactly where it's comming from. I see Terry got in while I was typing, yeah I agree. How "new" are the injector overflow hoses and are they OEM?

#4 09-20-2007, 10:38 AM

Quote:

Originally Posted by TMAllison

Warm it up and then spray the inj down with brake cleaner to get it clean and dry. Then fire it up and feel for fuel where the two halves of the inj thread together. More than likely is from there or from the nipples and return lines above that.

Clean and dry. Then fire it up and the leak is at the bottom of inj where it is mounted to the prechamber, if I increse the rpm fuel bubble up. Is this the inj oring, or is it the inj or a crack prechamber and how do I repair the leak? thank you so much for your help. J Hughes

TMAllison · #5 09-20-2007, 12:06 PM

No o-ring inside the inj. Very uncommon for fuel leak at inj to PC connection. Normally comes from above.

I believe the inj torque is 70-80nm but am not positive enough to say so difinitively. Someone else will chime in and confirm. I'd torque to the correct value next. Dont pull it or you will need to replace the washer at teh bottom of the hole. PC requires special tools to r & r. Inj requires 27mm socket. Some use 1-1/16" socket.

pawoSD · #6 09-20-2007, 12:08 PM

One of mine has been seeping a bit since I replaced the nozzles...from where the two halves go together....but its so minor that I don't care. I probably lose 1oz of fuel per month. Oh well...the rest are bone dry.

dufflespank · #7 09-20-2007, 02:11 PM

I don't have too much experience with cars, but this is one thing I know about.

I replaced my injector nozzles and upon reinstallation, found that every single one leaked from where the two halves of the injector mate. My problem was that I did not use a torque wrench when torquing the halves back together (the halves have a torque spec of 55 ft. lbs., also, the torque spec for injector-prechamber is 55 ft. lbs. as well), and I messed up the "lapped surfaces" that provide for a leak free seal. The fix is easy. Pull the leaky injector(s), seperate the two halves, and lap the circular surface (the surface with a tiny hole in it) of the top half by gently "sanding" it on 1200-1500 grit sand paper (you can find this grit at car places, but not hardware places). Also make sure that you clean everything with brake cleaner and that you reassemble using diesel fuel. This worked wonders for me, seeing as I no longer have leaky injectors. You may notice some imperfections on the "lapped surface," and the goal is to "rub those out."

pmari · #8 09-21-2007, 08:48 PM

Might want to pull them and try putting in new nozzle plates.