Quick OM60x Delivery Valve Leak Question - PeachParts Mercedes-Benz Forum

british_atlantic · #1 08-22-2020, 08:53 PM

Greetings

My '87 300SDL has developed a severe fuel leak while far from home. From some research it is probably the rubber o-rings on the delivery valves. My question about this is where the leaking occurs. Mine is leaking out of the fitting right by the base of the hardline that goes to the injector. It makes sense that fuel would flow up but I just wanted to make sure that this is the correct leak location for o-ring failure as opposed to something like a cracked line at the fitting or whatever.

I'll include a photo with a circle of where my leaking is occurring (not my photo so no visible leaks). Also here is a link to a great video I found on changing the o-rings. On a side note: he removed the lines without changing anything under the fittings which makes me think that there's nothing there to change as he was incredibly thorough. https://www.youtube.com/watch?v=PlB0Uc1qdUk

Thanks all for any assistance, I'm pretty sure that this common problem is what I am experiencing, but just wanted to confirm before digging in!

vollpreuss · #2 08-22-2020, 10:32 PM

I just went through this with my SDL number 6 line. There was a very small crack at the base of the flare. Had to remove the hard line to clearly see the crack as it was on the engine side of the flare. Fortunately I had a spare line and replaced it. No more leak at the injector.

Diseasel300 · #3 08-23-2020, 12:45 AM

Your leak is NOT the delivery valve O-rings. They'll be at the base of the delivery valve holders where they thread into the injection pump.

You have a loose or fractured hard line, or a cracked delivery valve holder. You can try snugging up the fitting. If you're lucky it's just loose.

jay_bob · #4 08-23-2020, 12:16 PM

Yes I have been there too, leakage from that point is usually a failure of the hard line.

If the line support clips are not properly installed this can happen as the lines will flex from the pressure pulses and you'll get fatigue cracking.

rwd4evr · #5 08-24-2020, 03:11 AM

O-ring/crush washer issues leak at the base of the splines where the two bolt down retainers are overlapping. That's a line crack or possibly the delivery valve itself. Try snugging the line up but......

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british_atlantic · #6 08-24-2020, 09:34 AM

ahh, thank you all!

When on the road far from home one must be resourceful; here's how I took care of this on a Sunday (read: nothing much open).

I could not get the correct part anywhere for the 300SDL so I had to "make" one. There was a 260E (read: not diesel) in an LKQ in Nashville, so I limped my car there from Memphis. Naturally the fuel lines were not the same, however the fitting going into the injectors was the same. The fittings on the other end, for the Jetronic, were entirely wrong. I bought two lines and then went to Home Depot for some hardware. I ended up using a nipple, two couplers, and some plastic o-rings as spacers. This all served to join the two Jetronic fittings together, making one line with the same injector-side fitting at both ends (it must be noted that for the Jetronic fittings to be threaded into the couplers the shims must be removed). Much to my surprise the hodgepodge of parts didn't leak and got me back to Cincinnati no problem. Here's what it ended up looking like:

barry12345 · #7 08-24-2020, 04:00 PM

Great emergency innovation. . Injector lines on diesels probably have a much thicker side wall as the pressure is so great. More importantly perhaps is to resist fatigue failure principally.

I would grab a used line off a wreck as soon as possible.

jay_bob · #8 08-25-2020, 05:34 AM

Indeed you are very lucky the Home Depot fittings held up to the 2000 psi injection pressure.

Yes please replace that line post haste with a proper one. And make sure you have all the pads, clamps, and clips intact holding the lines. They are not just there for beauty.

dlssmith · #9 09-01-2020, 06:27 AM

I installed all new hard lines and clips on my 603 last year. The old ones were worn where the clips were missing and the lines had rubbed against various surfaces. I've had hard line breaks before on a 603 and thought it time to preemptively change them. They are expensive and not all that easy to source. Ebay + dealer in my case. Tricky bit is fitting the new clips - lining up the new hard lines and making it all fit together.