Multifuel Injection Pump Leaking

[nbernard]

Hey everyone,
I have a fuel leak coming from the top of the cylindrical housing on the injection pump on my M51A2 Multifuel. It appears to be coming from under the thin plate (which does move a little) covering the top of the pump where the pressure lines connect. I've put a wrench on a couple of the line nuts and they feel tight. Any ideas or suggestions? I did turn the fuel up 1.25 turns on this pump last year, which brought a nice increase in power and a bit more smoke. Is this related? The truck still runs well, but while running, there's a constant drip.
Thanks,
Nathan

 

[gimpyrobb]

That plate is, nothing but a plate. It serves no purpose. The leak is coming from somewhere else. Spray it down with brake cleaner and blow dry with compressed air, then see where it comes from. Might have to rev it up to get it to leak.

 

[nbernard]

I cleaned and dried the pump before I started it today and it really looks like the fuel is coming out from under that plate. The only thing above the place where I'm seeing fuel is the pressure lines. But, it seems like if it was on the pressure side, it wouldn't run smoothly.
It leaks just fine at an idle... It is running down the side of the pump and dripping off the big line coming off the bottom of the pump. Probably a drip every 1-2 seconds.

 

[nbernard]

I guess that it's only right that I post a picture of the patient, AKA "Snowflake".

 

[gimpyrobb]

Love those dumps! With the bows and a cover on, they look tough!

I would try to loosen and re-tighten the injector lines then. If you just torque them down more, you can ruin the ferrule.

 

[doghead]

25ft/lbs max.

 

[nbernard]

Is there an o-ring or something on the lines that can fail? I have good torque wrenches, but not that will fit over a line nut like that. Any suggestions on getting the 25ft/lb accurate and consistent?
Thanks,
Nathan

 

[doghead]

No seals, it's a bite type ferrule. You can damage the ferrule by over tightening it.

This could work, http://www.bettymills.com/shop/prod...ent=Facility&gclid=CMb37Yzl9rkCFcmf4AodQ2cAyQ

Or you need a good sense of feel.

 

[nbernard]

So, I loosened and re-tightened the lines, and I noticed that they did feel much tighter than 25lbs when I broke them loose. I believe that I have them correctly torqued now, but the leak is bad enough that the truck will not start. While looking to see where the leak was coming from while my friend cranked the engine, I noticed a squirt of fuel coming off the side of the pump. After closer inspection, I could see that it was squirting out of a small allen screw just below the lines. I removed the allen, noticed that it has a hole in the center and that there appears to be little plunger valve inside the hole. I cleaned the allen screw and re-installed it, which appears to have stopped the squirt. What is that allen screw for? Some sort of bleeder? Now, fuel is just flooding out of the top of the pump around the line connections. I really need to use the truck, and unfortunately don't have a decent diesel shop in the area. What is involved with replacing damaged ferrules? Replacing the lines? How can I tell if the pump side of the connection is ok?
Thanks,
Nathan

 

[shenkmen]

My multi fuel leaked from the plug on top of the hydraulic head in the middle of the injector lines. Removing the plug and retorquing to spec stopped my leak. I want tk say the torque spec is around 50ft lbs (48???) but am not sure. Search the site and you'll come up with the spec. I think In posted it as well.

I removed the plate, cleaned the top of the hydraulic head with break cleaner first and compressed are before removing. Didn't want any junk in the head.

 

[shenkmen]

Here the thread I mentioned. For some reason Gimpy and Doghead we're involved there as well. Thanks for helping a newbie fellas'. I had my truck for two weeks at the time.

http://www.steelsoldiers.com/showth...ulic-Head-Help&p=724589&viewfull=1#post724589

 

[nbernard]

Yeah, I really appreciate the help, too. I've learned quite a bit about my truck from this forum, and by reading the TMs linked here. Thanks!
I've pulled and inspected the lines, and don't see anything that would obviously cause the leak with the ferrules. However, I did, to my surprise, find that there was no copper washer on the center hex bolt. I found a thread with a link to a Bosch manual that shows an exploded view of the pump and mentions the copper washer. Is this a special copper washer or a standard drain plug type? I am assuming that I've found my leak, although I can't figure out why/how the washer is missing. Any recommendations on finding a replacement?

 

[shenkmen]

Copper washers like that are called a crush washer. If you find the right size it will do it's job. I don't recall one there but that doesn't mean anything. Another member recently added one with good results.

 

[nbernard]

I found a crush washer and retorqued the center bolt. I cleaned all the ferrules and reinstalled them at 25 ft lbs. I can know see that there is fuel leaking from the number six and three lines. Those were also the two that felt the tightest and are the easiest to reach. I think that, despite the clear plate that says 25ft lbs max right next to them, someone over tightened them and damaged the ferrules. Do I have to replace the whole line? Are the ferrules somewhat standard? How do I tell if the head is damaged?
thanks,
Nathan

 

[nbernard]

I found a crush washer, installed it on the center bolt, and torqued it down. I think that stopped the leak from that bolt. I also ordered a set of new fuel lines from Memphis after trying unsuccessfully to find any one with the correct ferrule or any clue as to how to change them locally. I carefully cleaned and dried the hydraulic head and fitted the new lines, torquing them to 25ft lbs. Much to my dismay, the connection at the number three and six lines still leaks badly. I don't see any signs of damage to the head, but the person I spoke with at Memphis warned me to inspect for cracks in the head. Could there be a crack in the threads that I'm not seeing? Is this common? Any other suggestions about what could be causing this leak? When I crank the engine over, fuel just wells up out of the the connections, running down the side of the pump. Any help greatly appreciated.

Nathan

 

[sgtrisk]

Nathan,

Sorry bud, I don't have any advice for you. But I just started seeing the same thing on my IP yesterday. I won't go into any details on my issue, since I haven't had time to deal with it yet. (I'm still fighting with a brake system disaster and don't have the emotional energy to tackle something new. :'( ) Anyway, this thread has probably already saved me a bunch of headache. I can see fuel bubbling from the same area you indicated. From reading this thread, I'm almost afraid that I'm looking at purchasing a new IP. That may just turn this project into a "for sale" project. I almost could have purchased a new M923 for what I've about got in this. Wah, wah, wah. I know.

I was also surprised to see that the TM does not show any rebuild parts/kits for the IP. I can rebuild the hydraulic brake pack, but not the IP?? Grrr...

I'm now watching anxiously for any updates on your project.