Removing, rebuilding, reinstalling Hydraulic Head

Floridianson

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The governor will not go to wide open throttle ( WOT ) just because you pulled the shut down out to fast. Wide open throttle is caused by a sticking fuel control unit assembly. Happens when operators do not leave the shut down cable pulled out after they leave the truck. Then when they go to start it after it has been sitting for a longer time the stuck fuel control unit assembly that is now stuck in the full fuel position the engine goes to WOT. Then you change your shorts.
 

davemccoull

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For anyone interested I attempted to make a video to show the process as well. My phone is no video camera so I'm sorry for the grainy video. If I can get my hands on an actual video camera I'll gladly redo the video. Until that happens though, this is what I have. I know some people just need to see it in video and not pictures alone.

Hello Kenny
Just found your info and video on repairing HH, absolutely magic. The video got to re-assembly and then finished, does this carry on somewhere else? At least i know exactly what i am doing now, keep up the good work!.
Dave.
 

Mobilesparky

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Great post, Kenny!! I am going to be the local expert on this by the time I get her running again. I definitely had bad fuel and the button had definitely fallen off the bottom of the plunger. Bad part is, I must not have had the timing exactly in the right spot...difficult to see that scored tooth in the HH and I was a bit impatient, so now there is more gear showing than the half moom area, but it’s very evident when I look very closely at the IP gear where a piece has been broken off. I can only pray that the piece isn’t going to haunt me later as I am not sure where it went. Waiting on the oring kit for the HH now. Soaked the HH in solvent a few days and it looks great but looks don’t mean that it will work!
Re-painted the scored tooth, turned the plungerto be off just one tooth to correspond with the IP gear being off one tooth and it drops right in (how in the hell do ya get the engine to rotate to that perfect spot is beyond me!) Ihave all the injector lines off and tried to use my compressor wrench to rotate it a bit but still too much compression evidently. I have heard that loosening all the injector bolts and popping the loose slightly will release compression but wouldn’t having the lines off have to same effect? Maybe not.
Anyway, learning a lot the hard way. Here are a few photos that someone may enjoy. Wish me luck with re-assembly or if anyone has any words of wisdom, they are much appreciated!!
 

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Another Ahab

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Floridianson

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Great post, Kenny!! I am going to be the local expert on this by the time I get her running again. I definitely had bad fuel and the button had definitely fallen off the bottom of the plunger. Bad part is, I must not have had the timing exactly in the right spot...difficult to see that scored tooth in the HH and I was a bit impatient, so now there is more gear showing than the half moom area, but it’s very evident when I look very closely at the IP gear where a piece has been broken off. I can only pray that the piece isn’t going to haunt me later as I am not sure where it went. Waiting on the oring kit for the HH now. Soaked the HH in solvent a few days and it looks great but looks don’t mean that it will work!
Re-painted the scored tooth, turned the plungerto be off just one tooth to correspond with the IP gear being off one tooth and it drops right in (how in the hell do ya get the engine to rotate to that perfect spot is beyond me!) Ihave all the injector lines off and tried to use my compressor wrench to rotate it a bit but still too much compression evidently. I have heard that loosening all the injector bolts and popping the loose slightly will release compression but wouldn’t having the lines off have to same effect? Maybe not.
Anyway, learning a lot the hard way. Here are a few photos that someone may enjoy. Wish me luck with re-assembly or if anyone has any words of wisdom, they are much appreciated!!
Yea going to haunt you. Yep it will break off if the Head was installed off correct timing and you line up the mark with score / red line and try and remove it with force. It can all so break if the head was installed with the correct timing but someone did not line up the head mark / score just right and tried to remove with force. The piece is called the plunger guide just incase anyone want to know from the video. Not the butterfly valve. You might get lucky and get the head back in with correct timing so just double check that when the HB and advance window are on there correct marks the head will be just about one tooth off to the rear. Also be very care full if you polish the plunger and when you go to install it do not hold it to long. The heat from your hand will make it fit tighter or not at all,
 

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plym49

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Two questions:

  1. If the retaining plate cracks, can the HH still function as long as the plunger is free? (Thinking in the event that a road-side, expedient repair is needed.)

  2. What is the best (only?) way to turn the motor by hand to line up the marks, once again assuming the need for a road-side repair?
 

schriffsMN

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Two questions:

  1. If the retaining plate cracks, can the HH still function as long as the plunger is free? (Thinking in the event that a road-side, expedient repair is needed.)

  2. What is the best (only?) way to turn the motor by hand to line up the marks, once again assuming the need for a road-side repair?
To turn the engine over, put the transfer case in neutral and the transmission in 5th gear. (Park brake applied / wheels chocked, of course.) Take a bar or large screwdriver and stick it in the yoke of the driveshaft between transmission and transfer case to turn that shaft. Could probably also use big pipe wrench on the shaft.

Sent from my SM-T387P using Tapatalk
 

GunInstructordotcom

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I'm back to working on my 1970 M35A2C LDT multifuel. I had the leaking HH problem, so I removed the HH and replaced the three o-rings. When I took the injector lines off the HH, I discovered two of them had some orangy gunk down in the HH hole after removing the lines. I cleaned the gunk out and blew compressed air through the injector lines to make sure they were clear. I put it all back together and now the engine will not idle for long and the engine will surge back and forth when I have the hand throttle on a bit. It runs OK for a while, then surges, then tries to die. No leaks anywhere, and I checked the idle lever inside the cover. It moves freely and snaps back to the middle. I'm out of ideas now. Any advice?
 

Mobilesparky

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I'm back to working on my 1970 M35A2C LDT multifuel. I had the leaking HH problem, so I removed the HH and replaced the three o-rings. When I took the injector lines off the HH, I discovered two of them had some orangy gunk down in the HH hole after removing the lines. I cleaned the gunk out and blew compressed air through the injector lines to make sure they were clear. I put it all back together and now the engine will not idle for long and the engine will surge back and forth when I have the hand throttle on a bit. It runs OK for a while, then surges, then tries to die. No leaks anywhere, and I checked the idle lever inside the cover. It moves freely and snaps back to the middle. I'm out of ideas now. Any advice?
You said the lever inside snaps back to the middle…if you’re actually talking about the shut off lever, it shouldn’t be coming back to center per se…it may be preventing the fuel from fully flowing to the injector lines. Also, did you clean out the tiny little port in the center plunger? It’s been awhile since I did mine so can’t be more specific right now, but there are a few intricacies that you need to really pay attention to on this job. Check out YouTube as well. There are a couple guys there that did a great job covering these issues.
 

jeepin

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I'm out of ideas now. Any advice?
Mine did that and even though the shutoff assembly seemed to be free when I moved it by hand with the cover off, the engine would hunt at idle. I removed the safety wire and backed the two screws out even more and re-wired and it solved it. So my idea is that maybe the screws have to be looser than you think they should be to let the assembly move freely and smooth the idle.
 

GunInstructordotcom

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Mine did that and even though the shutoff assembly seemed to be free when I moved it by hand with the cover off, the engine would hunt at idle. I removed the safety wire and backed the two screws out even more and re-wired and it solved it. So my idea is that maybe the screws have to be looser than you think they should be to let the assembly move freely and smooth the idle.
Mine is also surging when I set the hand throttle at about 1100. It runs a while fine, then surges, then tries to die if I don't work the hand or foot throttle. Big puffs of smoke when I accelerate the throttle. I can back off the screws a tad and see what happens.
 

Mobilesparky

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Mine did that and even though the shutoff assembly seemed to be free when I moved it by hand with the cover off, the engine would hunt at idle. I removed the safety wire and backed the two screws out even more and re-wired and it solved it. So my idea is that maybe the screws have to be looser than you think they should be to let the assembly move freely and smooth the idle.
Good advice on that…there is a sweet spot for sure so that it still has pressure on the oring. Only other thing that I can suggest is to change all of your fuel filters and also assuming that you got the red/grooved tooth lined up properly upon installation of the HHO…and bled the lines really well…sounds like you had gunk in them anyway and so who knows what kind of psi you’re actually getting at the injectors or perhaps some crap broke loose and now is in the injectors themselves.
 

GunInstructordotcom

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Good advice on that…there is a sweet spot for sure so that it still has pressure on the oring. Only other thing that I can suggest is to change all of your fuel filters and also assuming that you got the red/grooved tooth lined up properly upon installation of the HHO…and bled the lines really well…sounds like you had gunk in them anyway and so who knows what kind of psi you’re actually getting at the injectors or perhaps some crap broke loose and now is in the injectors themselves.
Thanks for the advice. If I screwed up and moved the HH red tooth one slot either way would that result in the engine running the way it is? How do I know if an injector is malfunctioning? Is there a way to diagnose each injector?
 

GunInstructordotcom

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You just have air in it still. Get it out and drive it.
I let it warm up yesterday and it didn't change anything. I'll try a more thorough warmup with higher rpms tomorrow. I have to top off the Dot 5 brake fluid, top off the axle and trans oils, and check the air in the tires before I try moving it. It has been sitting for about two years now.
 

Jeepsinker

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Yeah you have to drive it. Get it out and drive it hard. Think 17 year old that just got his license hard.

This happens every time I've pulled a hydraulic head. It clears up pretty fast though. Sometimes it can take around 30 miles to clear up but it always does.

It could also be binding slightly if you bent the governor rod even the tiniest bit but usually that causes a slow throttle reaction in both directions. It also may just be sticky components from old oil in the rear governor section. I've seen that too.
 

Floridianson

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Thanks for the advice. If I screwed up and moved the HH red tooth one slot either way would that result in the engine running the way it is?
Timing is easy enough too
Thanks for the advice. If I screwed up and moved the HH red tooth one slot either way would that result in the engine running the way it is? How do I know if an injector is malfunctioning? Is there a way to diagnose each injector?
As for is timing correct? Not the best time for second guessing did I get the timing off and should have been checked just after head install. Better news if it is off you know what has to be done to correct it just a real pain now. Yes off timing is important to how engine runs so might as well check it. As for injectors if you think there is a problem with them not popping right then removal / cleaning and testing with injector out and pop tester. Then to the plunger sleeve / fuel control unit assembly working free and clear. Yes needs to work very free with no binding.
 

GunInstructordotcom

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Today I started it up and it wouldn't hold an idle, but set at 1200 it ran fine. And then I saw the diesel leak. It appears to be coming either from the top of the shutoff lever cover gasket, or the HH base just above it. A fine constant stream. I guess I need to take it all apart and start over. Maybe this is a good time to buy one of the Chinese HH assemblies and replace the unit. I realize I am in over my head because I don't have a clue why it is leaking. Perhaps this was the problem all along and is not just worn o-rings. I would like to have a mobile diesel mechanic work on it, but I can't afford the thousands that the bill would be.
 
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