Hydraulic head fuel leak

[sigley89]

Last summer, 2019, we were cruising around in the M35A2 when stopped at a light it died. It’s never done it before so started it back up and the light turned green and then drove off. No issues after that until we stopped in a parking lot and turned it off. We ate and went to start it up and wouldn’t fire. Found a fuel leak at the hydraulic head and the injection pump. It was a very strong stream (arterial kinda leak). We had a guy driving a Subaru Outback stop by to check the deuce out and he was willing to “pull start” the deuce. Put it in 3rd and while rolling popped the clutch. Started up and ran but needed the throttle pulled out or the peddle to the floor to idle and drive. Made it home and parked it.

Winter came and went and now spring is here, I took the hydraulic head off and replaced the 2 O-rings on the HH. The old ones look brand new but replaced them anyway. Got it back together and same issue but less of a leak, but still bad enough it won’t fire. Is this something someone has run into before? In the attached picture, it is leaking in the big red circle under line #6 and to the right of the bolt. The smaller circle is an Allen head type of screw and it kinda seems to be leaking out of it. The Allen screw looks like it has a hole. Could that be my problem?
Any help would be appreciated.

 

[sigley89]

***UPDATE***

it looks like the hole in my allen plug is the issue. See attached image
So now my question is does anyone have a spare they’d be willing to give me or sell to me?

 

[davidb56]

thats drilled. PM " Rustystud" and ask him about it. maybe there is a ball and spring behind it or its a vent, but it looks intentional, not a defect.

 

[sigley89]

I was talking with the guy on youtube (tacticalrepair) and he said there shouldn't he a hole in it.

 

[ToddJK]

When my delivery valve bolt (that's the star pattern bolt sticking out of the HH) got a crack in it, I emailed TNJ Murray, Eric's Surplus, Eastern Surplus, and few others. TNJ Murray are the ones who got a hold of me and found one as these don't seem to be a common thing, lol. If that Allen screw is defective, I'd email them with a picture and see what turns up.

*Edit*
I'd also ask @Rusty Stud about it, as I have never removed that screw, like Davidb56 said, could be another part that was involved that was lost or something.

 

[rustystud]

That plug has the hole in it to hold in place what I call a "stopper" . It has a stem that fits in that hole aligning it to the pump housing. There should have been that stopper when you pulled out that plug.
With the amount of pressure behind that plug there is no way to keep that truck running.
In all honesty I don't know how you could have had that stopper missing all this time. That is straight pump pressure to the injectors. Someone had to have removed the stopper.
There are six of these plugs. They are there to plug the holes left after drilling out the hydraulic head for the six injectors. With all that pressure the manufacturer incorporated that extra stopper to hold back pressure of the pump. Here's a picture showing the stopper (left) and the plug with the stopper installed (right) .

 

[ToddJK]

That plug has the hole in it to hold in place what I call a "stopper" . It has a stem that fits in that hole aligning it to the pump housing. There should have been that stopper when you pulled out that plug.
With the amount of pressure behind that plug there is no way to keep that truck running.
In all honesty I don't know how you could have had that stopper missing all this time. That is straight pump pressure to the injectors. Someone had to have removed the stopper.
There are six of these plugs. They are there to plug the holes left after drilling out the hydraulic head for the six injectors. With all that pressure the manufacturer incorporated that extra stopper to hold back pressure of the pump. Here's a picture showing the stopper (left) and the plug with the stopper installed (right) .
View attachment 881125

Is that stopper made of steel? Is it possible that stem can break off and the plug floating within the HH?

 

[rustystud]

Is that stopper made of steel? Is it possible that stem can break off and the plug floating within the HH?

Sorry I haven’t gotten back to you. I’m in North Carolina right now visiting my son.
Yes that stem can break off and twist in it’s bore.
I’d send you one but it will be about a week before I get home and can look for it.
They are made of hardened steel.

 

[gimpyrobb]

I probably have one at the barn. Let me see what I can dig up.

 

[ToddJK]

Sorry I haven’t gotten back to you. I’m in North Carolina right now visiting my son.
Yes that stem can break off and twist in it’s bore.
I’d send you one but it will be about a week before I get home and can look for it.
They are made of hardened steel.

No problem Rusty, I was just wondering in case if I had that problem, help me understand what's going on. I won't need one, at least not right now, sigley89 is the one who would need it should you or Gimpy find one.

 

[sigley89]

So i think the “stopper” stayed in the HH. Should it have came out with the allen plug?

 

[rustystud]

So i think the “stopper” stayed in the HH. Should it have came out with the allen plug?

Yes. You can pull it out with some needle nose pliers though. Then clean it up and reinstall the stopper and plug.

 

[sigley89]

Yes. You can pull it out with some needle nose pliers though. Then clean it up and reinstall the stopper and plug.

Ok ill do that tomorrow and see if that fixed my fuel leak. Ill post an update

 

[sigley89]

Has anyone used the the NEW Reproduction Hydraulic Head for the M35A2 multifuel truck with the LDT465 motor? There is one on ebay for $500

Link to HH

I have someone on Facebook willing to sell a used one for $400 but if the reproduction ones are solid and have no issues id spend the extra $100 and get that one.

 

[DaneGer21]

Has anyone used the the NEW Reproduction Hydraulic Head for the M35A2 multifuel truck with the LDT465 motor? There is one on ebay for $500

Link to HH

I have someone on Facebook willing to sell a used one for $400 but if the reproduction ones are solid and have no issues id spend the extra $100 and get that one.

You should definitely be able to find a HH for less than $400…hopefully

 

[sigley89]

You should definitely be able to find a HH for less than $400…hopefully

Whats an average price for one?

 

[87cr250r]

These guys sell OEM parts for all major pump manufacturers. I would start with them.

Diamond Diesel & Turbo Service, Inc. - Diamond Diesel and Turbo Services, Inc.

Diamond Diesel & Turbo Service, Inc. Diamond Diesel and Turbo is your factory (OE) authorized factory Service Dealer for Diesel Fuel Injection pumps, Diesel Injectors, Diesel Fuel Additive and Turbochargers in California and Nevada. Serving our customers since 1968 Diamond Diesel and...

www.diamonddiesel.com

 

[sigley89]

These guys sell OEM parts for all major pump manufacturers. I would start with them.

Diamond Diesel & Turbo Service, Inc. - Diamond Diesel and Turbo Services, Inc.

Diamond Diesel & Turbo Service, Inc. Diamond Diesel and Turbo is your factory (OE) authorized factory Service Dealer for Diesel Fuel Injection pumps, Diesel Injectors, Diesel Fuel Additive and Turbochargers in California and Nevada. Serving our customers since 1968 Diamond Diesel and...

www.diamonddiesel.com

Dead link unfortunately. Maybe their site is down.

 

[Floridianson]

Has anyone used the the NEW Reproduction Hydraulic Head for the M35A2 multifuel truck with the LDT465 motor? There is one on ebay for $500

Link to HH

I have someone on Facebook willing to sell a used one for $400 but if the reproduction ones are solid and have no issues id spend the extra $100 and get that one.

Is that a Chinese reproduction. The only reason I ask is there are 87 of them available. Some have bought the ones from China and had no problem with them.

 

[ToddJK]

Is that a Chinese reproduction. The only reason I ask is there are 87 of them available. Some have bought the ones from China and had no problem with them.

Didn't they change the design on the plunger for the button, so it doesn't fall off as easily?