Constant injector return hose leak 1999E300 - PeachParts Mercedes-Benz Forum

ROLLGUY · #1 11-12-2014, 05:33 PM

My friend came over the other day with his car smelling like Diesel, and I saw all the return hoses wet with fuel. I had a length of hose, and replaced them, and they all are leaking again. Just a 15 mile drive fills up the well around the injectors. All the hoses seem to still be on the barbs, so I can't figure out why they are leaking. Could there be a clog in the return line? Can I use compressed air to try to force air through the line back to the tank? I did try blowing in the new hose connected to the nipple on the filter housing, and there was resistance. I am not sure how much resistance there should/could be without it starting to leak. I did pull the hose off the nipple and started the engine, there was a steady stream of fuel exiting the nipple before I plugged it with the return hose. I started the engine and looked for leaks, and there was none. I even filled the injector wells with water to get all the fuel out, and then sent him on his way. He called 10 minutes later saying he pulled off the road and popped the hood to find the wells full of fuel again. What can I do? Anyone have any ideas?

TMAllison · #2 11-12-2014, 08:03 PM

Have heard of folks cutting (scoring) the return lines in order to help remove them and scratching the barbs resulting in a leak(s).

A tremendous amount of fuel is unused and returned to the tank.

Suppose you could go the Viton/mini clamp route to seal it up. Not easy down inside the inj wells though.

jay_bob · #3 11-12-2014, 09:43 PM

Attn OM606 - inspect under the engine cover

Been there done that. It was the injection line itself leaking. Hard to spot the clear fuel running down the sides of the injector.

ah-kay · #4 11-12-2014, 09:45 PM

Rich, how could you let such a simple return hose stumped you? I am disappointed

. You can put compress air into the return line. I did it all the time to purge fuel back into the tank when I change the injectors. It is less messy. Just open the gas cap , put compress air thru and you will hear a lot of gurgling noise from the tank.

ROLLGUY · #5 11-13-2014, 01:06 AM

As it turns out, I must have poked a hole in one of the new lines when I installed it. I could not have imagined that so much fuel would have come out of that little hole in that short of time. I did blow out the line with the fuel cap off, and it seemed to be clear. I then left the cover off and told my friend to drive around the block after replacing the lines a second time. When he got back, all the wells were full and the entire bottom of the car was soaked with fuel. After sucking the fuel out of all the wells, I started the engine and saw the offending hose. After replacing it, all is well now. I guess every time I replaced the hoses I must have put a small hole in at least one of them. It did help that I found a length of thinner cloth covered hose. It was much easier to install without tools (some nipples are very close to the wall of the well). Oh well, lesson learned. Next time I will run the engine a little longer before I call it good and send him on his way.....Rich

funola · #6 11-13-2014, 09:13 AM

How did you poke a hole in the hose??? What tool did you use? I can't imagine how that can happen unless you used something sharp. For hard to reach barbs I use long nose pliers near the hose end, dip the hose in diesel to lube and they go on easy with no issues.

ROLLGUY · #7 11-13-2014, 11:01 AM

Quote:

Originally Posted by funola

How did you poke a hole in the hose??? What tool did you use? I can't imagine how that can happen unless you used something sharp. For hard to reach barbs I use long nose pliers near the hose end, dip the hose in diesel to lube and they go on easy with no issues.

That is exactly the tool I used. The larger diameter hose I used at first needed a little help to get it on the nipple, but the smaller diameter hose I have on there now, was easy to put on without any tool. I am now sure that is how the leak got there in the first place= using long nose pliers close to the end.

funola · #8 11-13-2014, 05:33 PM

Quote:

Originally Posted by ROLLGUY

That is exactly the tool I used. The larger diameter hose I used at first needed a little help to get it on the nipple, but the smaller diameter hose I have on there now, was easy to put on without any tool. I am now sure that is how the leak got there in the first place= using long nose pliers close to the end.

Long nose pliers should not damage the hose unless you squeezed it too hard or the tips of your long nose has sharp teeth.