Another leaking hydraulic head

[Woodsplinter]

Hey folks, I've read many of the threads about leaking hydraulic heads but I'm not sure which direction to start in.

Mine started leaking on my A2 deuce yesterday. (LDT465-1C engine) The first photo shows a pencil pointing to the area where the leak appears to be. (At least in that area).

I have verified all the injector lines are tight as are all the mounting bolts. The truck runs fine and always has- just sprung a leak.

I removed the cover on the lower portion of the HH where the stop cable enters and found it filled with black oil. (Only run diesel, never WMO) Turned on the in-tank pump but saw nothing leaking. Only appears to leak after running for a few minutes. While running, I could see fuel dripping in the area of the pencil tip.

I'm not sure which direction to go next- replace the HH, just the O-rings??

I've read TM's till my brain is mush (not really much different than normal-lol).

Any advice would really be appreciated!

 

[Ford Mechanic]

From what I've read here those 12 point plugs crack at times. So you might need to replace it. I think I remember someone saying that they were lapped fitted? How you do that to a plug I don't know. But they had several and just tried them until they found one that fit correctly. I think it was Gringletaube that I read this info from. And the oil in the cover I would think to be normal. Mabey someone else will come set us straight.

 

[Keith_J]

That is the cover to the delivery valve. There is a spring under it, forcing the lapped delivery valve into the seat in the head.

Take the plug out and see why it is leaking. I would venture there is a crack which cannot be repaired. But it could be loose.

Yes, the injection pump is lubricated with engine oil on the bottom end. Only the plunger in the hydraulic head is lubricated with diesel. From the quill down, it is all engine oil.

 

[Rodger]

If you have to replact the head, I found removing the fender made it easier.

Rodger

 

[Woodsplinter]

Ok thanks everybody- I'll pull that plug out today and check it. I'll let you know what I find.

 

[Keith_J]

Also, the O-rings do not seal the delivery valve. They are only sealing the low pressure side of the head, high pressure is always metal to metal seal.

 

[Woodsplinter]

Well I got the delivery screw out and it was in TIGHT! I don't see any cracks anywhere- really can't see where it could be leaking from unless the metal-to-metal seal isn't working anymore.
Is there anything I could put on that metal seal to "seal" better?

Thanks,

Mark

 

[Welder Sam]

Mmm... interesting

 

[Woodsplinter]

The leak APPEARS to be fixed. After removing the screw I polished some rust off the sealing surface using 6000 grit abrasive paper. I was very careful not to alter the shape of the metal surface. I then cleaned off the mating surface on the HH using Q-tips soaked in brake cleaner.
Next I put a very thin film of thread sealant on the mating surfaces and reinstalled the screw. Waited a few minutes then started the engine. I thought I had it in tight but I had a spray of diesel coming from around the screw. Re-tightened using a 2' pipe on the ratchet and it stopped.

Cleaned everything off, dried it and ran engine at various speeds. No leak evident at this time but will still need to road test it to verify.

Thanks for all the input everybody, I'll let you know the results of the road test.

Mark

 

[DieselBob]

Just a FYI, in the TM 9-2910-226-34 it does say to tighten and loosen the screw 3 times.

"Install valve (C), delivery valve spring (B), and screw (A), and torque tighten valve screw to 40-45 foot-pounds. Loosen screw and retorque to 40-45
foot-pounds two more times."

 

[Woodsplinter]

Thanks Bob- I missed that! I was reading until 2AM and had blood in my eyes by then.
Back out to the truck with tools...

 

[Woodsplinter]

Did the road test after torquing & re-torquing but it still leaks. Not as bad but too much to leave as is.
Replacing the entire HH would solve the problem but that's expensive and that's a job way beyond me- seems to be lots of horror stories about replacing this "infernal machine"!!

 

[DieselBob]

Just thinking out loud, but I wounder if a thin copper washer like that used on a banjo bolt for a brake cylinder would work. Just throwing it out there. The one concern I would have is the fact the screw would now be out slightly and that would lesson the tension on the spring.

 

[Keith_J]

The hydraulic head swap isn't needed unless there is a crack in the head itself. Finding this would require careful inspection with magnification. The pictures you posted don't show detail enough to rule this out.

Also, a new cap screw would help. You could try some dry moly spray on the existing screw's flange but it appears to be chewed up. Be sure to use the correct 12 point socket. As you probably know, this is a rare part.

Replacing a hydraulic head isn't too terribly difficult. Remove the injector lines, then pull the stop solenoid cover. Remove the safety wire and two screws. The governor rod's hitch pin is then removed from the control lever, which can now be removed. Now you can see the timing mark, rotate the engine until the red tooth on the spur gear aligns with the timing mark. Remove the 4 bolts securing the hydraulic head and pull the head out.

The quill gear will rotate slightly, just rotate the engine to align with window on the quill gear so the new hydraulic gear will align. The new head cannot be installed without the quill gear being aligned, it is visible.

If Gimpy can replace the HH, anyone can

 

[Woodsplinter]

Bob, that's a great idea! I hadn't thought of that- cheap to do and nothing lost if it doesn't work.
Keith, I really don't think there's a crack in the head- UV dye might be necessary if all else fails. You're explanation of the procedure makes sense to me now- you condensed multiple threads into one paragraph! Thank you!
Gonna try the washer next but it will have to wait until Sunday- doing a big car show tomorrow with my Desert Warriors club. Will post pics for all of you.

 

[Keith_J]

The function of the delivery valve is a check valve in the system, I doubt a thin copper washer would reduce spring force enough to matter. Worth a try.

 

[Keith_J]

If you must pull the hydraulic head, turn the engine over by putting the transmission in 5th gear with transfer case in neutral. Use a pry bar though the yoke on the universal joint between the transmission and transfer case. A 3/4" round bar, 2' long is all you need.

 

[Woodsplinter]

Ok Keith, thanks!

 

[Woodsplinter]

Haven't located a thin copper washer that will fit- gonna try to find some thin copper and cut my own. The leak is very minimal but needs to be fixed.
I'll post the previously mentioned pics on the "what did you do to your deuce" thread.

 

[6x6junkie]

harbor freight has them kits