OM617: Getting awful wet around the fuel pump - PeachParts Mercedes-Benz Forum

Screwdriva · #1 11-03-2020, 03:51 PM

1984 300D Auto. 145K miles. Noticed substantial wetness the fuel hard lines leading to the injectors. Injector #5 is also very damp despite changing the fuel return hoses.

Is it time to replacing the delivery valve seals? Anything else I should be focussing on while doing this job? And finally, got a part number for the kit handy?

Many thanks in advance!

Shern · #2 11-03-2020, 04:03 PM

If the seals are leaking, there’s no reason the injectors should be wet.
Wrap some paper towels around each hardline and see if you can pin point the source.
Possible the hardlines arent seated properly. I’ve made that mistake...

Diesel911 · #3 11-03-2020, 04:28 PM

Spray brake cleaner to dry every thing off and then see if you can find the leak. If the engine is running keep your fingers away as the pressure in the hard lines is sufficient to inject into you skin were it causes some serious issues.

If the clamps on the hard lines are missing that can cause the hard line to crack or sometimes they crack anyway. I recently lost one of my Hard Line Clamps as I forgot to tighten it. Not happy about that.

Diesel911 · #4 11-03-2020, 04:33 PM

Note on the MW Fuel Injection Pumps at the top there is a 13mm hex nut on each side of the Delivery Valve. Loosening those nuts and moving the plate below ruins the calibration. I am saying this because there has been at least 2 members over the years that have had a leak below that plate (it is actually the top of the Element Body) down.

It takes special instructions to remove the Element and replace the Seals/O-rings under there if there is any hope to get it back to the same position. It requires scribing marks and measurements and the Shims under the Element need to be put back exactly where they came from.

Shern · #5 11-03-2020, 07:20 PM

Quote:

Originally Posted by Diesel911

Spray brake cleaner to dry every thing off and then see if you can find the leak. If the engine is running keep your fingers away as the pressure in the hard lines is sufficient to inject into you skin were it causes some serious issues.

If the clamps on the hard lines are missing that can cause the hard line to crack or sometimes they crack anyway. I recently lost one of my Hard Line Clamps as I forgot to tighten it. Not happy about that.

Do you need? Shoot me a message, I’ve spares.

Diesel911 · #6 11-03-2020, 09:40 PM

Quote:

Originally Posted by Shern

Do you need? Shoot me a message, I’ve spares.

I bought another injection pump right after I got my Car back in 2007. It cam with the fuel injection hard lines. I just have to find that and remove the one clamp that I lost.

vwnate1 · #7 11-05-2020, 11:21 PM

Subscribed to find out what the problem was .

I've had a few injectors simply begin leaking where they're assembled .

I also had the steel fuel pipe begin leaking where it attaches to the injector, I tried tightening, cleaning and so n, the end repair was a used steel pipe from the junkyard .

Screwdriva · #8 11-06-2020, 05:13 AM

I believe there are two issues that are separate:

1) diesel pump delivery seals need replacing. If anyone would share the correct part # and procedure, I'd be grateful

2) Something's up with injector #5. Time to send this set to Greazzer

BillGrissom · #9 11-07-2020, 01:01 PM

A little note, if the steel hard lines aren't cracked at the injector end (happens), the leak might just be from the metal-metal contact not being perfect. There are thin copper or aluminum disks to help seal. In aerospace, we term them "soft seat" for use on flared AN fittings. I have seen them on ebay under a similar name. The M-B ends aren't flare, but "should work", indeed I recall using one a long time ago there. Just measure w/ a caliper to see which AN size will fit.

You didn't mention, but if the lift-pump (in title) is leaking, you can buy rebuild kits for $15 on ebay. Those Bosch pumps have standard guts, so same rebuild as for many tractors and such. The body is different though, so if you tried to swap in a tractor lift-pump the fittings would likely protrude into the K-frame. Worst-case someday when you can't source a lift-pump is you could install a block-off plate and plumb in an electric fuel pump.

Screwdriva · #10 11-08-2020, 03:59 PM

The lift pump is fine and isn't leaking. That said, I will pay for Greazzer to rebuild the injectors and the pump at the same time.

I'm pretty sure the leak is coming from the O-ring/ copper washers around the delivery valves (See video below).

https://www.youtube.com/watch?v=PlB0Uc1qdUk

I am struggling find the part numbers to replace them with dealer supplied replacements.

Diesel911 · #11 11-08-2020, 04:08 PM

Quote:

Originally Posted by BillGrissom

A little note, if the steel hard lines aren't cracked at the injector end (happens), the leak might just be from the metal-metal contact not being perfect. There are thin copper or aluminum disks to help seal. In aerospace, we term them "soft seat" for use on flared AN fittings. I have seen them on ebay under a similar name. The M-B ends aren't flare, but "should work", indeed I recall using one a long time ago there. Just measure w/ a caliper to see which AN size will fit.

You didn't mention, but if the lift-pump (in title) is leaking, you can buy rebuild kits for $15 on ebay. Those Bosch pumps have standard guts, so same rebuild as for many tractors and such. The body is different though, so if you tried to swap in a tractor lift-pump the fittings would likely protrude into the K-frame. Worst-case someday when you can't source a lift-pump is you could install a block-off plate and plumb in an electric fuel pump.

The M type fuel injection pump lift pump kits (has disc valves) differs from the MW type lift pump kits (which has kind of T shaped plastic valves).

You also want a kit that has the 5mm O-ring in it. Note that here is a valve and spring kit that has no O-ring in it. If you get the valve kit you need to find an O-ring as the O-ring is an important part.