OM606 diesel leak - PeachParts Mercedes-Benz Forum

carreraplanes · #1 09-13-2017, 05:47 PM

Diesel is building up in the wells in the head that surround each injector. The fuel builds up, overflows the top of the well and runs down the side of the block at the rear, dripping out onto the road. I've replaced the low pressure return small flexible pipes but it's still building up. The nuts carrying the high pressure fuel to each injector are done up tight. However according to Mercedes the low pressure return pipes are not clipped as apparently they do not need to be due to the low pressure. Can't see that the fuel can be coming from anywhere other than the flexi pipe connection to the injector. Wondering if anybody else has experienced this

jay_bob · #2 09-13-2017, 05:53 PM

I had this problem too...

Are all your hard line clips and pads secure? These are vital because if they are not in place, the hard lines flex a minuscule amount with every injection pulse. Over time the line will get a stress fracture at the nut or another place along the line.

Prior owner of my car had used zip ties for securing several hard lines in place where the clips had failed. This caused my #2 line to weep diesel.

If it is truly leaking from the low pressure "leak oil" hoses then check to make sure no one used a utility knife to slice off the old hoses. If that is done then a small scratch can be made in the fitting, which allows the fluid to weep past the hose and leak.

http://www.peachparts.com/shopforum/diesel-discussion/341600-attn-om606-inspect-under-engine-cover.html

Murkybenz · #3 09-14-2017, 07:39 AM

Also when removing old leak off lines a small bit can get left behind if they are quite rotted, this bit then stays on the stub and stops the new line fitting properly and after a few days the injector well is filled up and it then overflows along to the next etc.

carreraplanes · #4 12-04-2017, 06:17 PM

Thanks Jay Bob, when I got under there I discovered that 3 of the six injectors were indeed scored where the low pressure lines push onto the nipple that is part of the injector. I polished the scratches as best as I could with the injectors in-situ and bought some sealer that is for fuel system components (ThreeBond 1184) thinking that would be sufficient to seal the low pressure return.

However it is still leaking and filling up the wells around the injectors. I might need to replace the injectors which actually look quite new. That would be a shame seeing as it is just a small scratch but needs must I suppose. It looks to me as if the injector breaks into 2 pieces, nozzle and body, perhaps I could just replace the body? Can't see anything on Peach/Pelican.

Anybody have a view on this?

Many thanks,

Keith

Diseasel300 · #5 12-04-2017, 07:00 PM

It's worth adding to the mix here that the little barb fittings that the return hoses connect to can become loose. I had this problem recently after cleaning my injectors in an ultrasonic bath. A quick pop with a dowel rod and a hammer ended the leaking (and it was significant on a couple of them).

carreraplanes · #6 12-05-2017, 06:36 AM

Many thanks 300, think I'll give that a shot next!!!

torsionbar · #7 12-05-2017, 11:51 AM

Quote:

Originally Posted by jay_bob

I had this problem too...

Are all your hard line clips and pads secure? These are vital because if they are not in place, the hard lines flex a minuscule amount with every injection pulse. Over time the line will get a stress fracture at the nut or another place along the line.

Prior owner of my car had used zip ties for securing several hard lines in place where the clips had failed. This caused my #2 line to weep diesel.

^ This. The rubber pads and grey plastic clips are essential. If they're missing, or replaced by a negligent mechanic with zip-ties, the high pressure lines will become damaged over time and begin to leak.

The rubber return hose does not require any clips or sealant whatsoever. The fuel barely dribbles through them, zero pressure. Applying sealant to them runs the possibility of fouling the fuel injectors, and making the hoses more difficult to replace in the future..

When you replaced the return hoses, did you also replace the end plug? The end plug is a common leak point as folks often forget to replace it.

Maxbumpo · #8 12-05-2017, 11:54 AM

Quote:

Originally Posted by carreraplanes

I might need to replace the injectors which actually look quite new. That would be a shame seeing as it is just a small scratch but needs must I suppose.

Keith,

Another idea: remove injectors, clean off the damaged barbs, fill the damage with JB Weld or other epoxy suitable for high temperature use, sand/polish the barbs, take apart the injectors (keep parts for each injector together) and lap the body joints, clean clean clean, re-assemble and install with new heat shields and new low-pressure return lines.

Maxbumpo · #9 12-05-2017, 11:57 AM

Totally agree that the hard lines are suspect, or even the injector bodies. You should clean out / off all the spilled fuel, and then carefully observe the running engine. In my area, diesel fuel will fluoresce under a black light - helpful for locating a fuel leak if you have a dark area to work.