HH Rebuild

In this video I'm going through the basic steps of rebuilding your Multifuel Hydraulic Head, more commonly called an HH. If you have a multifuel and it's stopped running, there is a chance that you have a bad HH. Despite what the injection shops claim, many times these can be rebuilt.
If interested in parts for any of your military vehicles please check out my website where you're find a selection of vehicle parts to backpacks. mvpartstore.com/

[@13foxtrotfarmer2]

Thanks a ton for this. Just rebuilt the HH on a new duece I got. First time being that deep. Had to make the butterfly clip but I got it back together and it runs just fine. Thanks again for the video.

[@MVPartStore]

What did you make the clip out of and do you think it's a permanent fix? I have considered making them but was concerned the hardening process would send the cost too high when I can sell new AMBAC replacements for $65. I'd really like to hear how well it works out for you. [e-mail]

[@13foxtrotfarmer2]

WoodWorking With ADD I just made it out of mild steel. Cut it out on our waterjet. I can't imagine them needing to be hardened seeing as the only thing they do is keep the plunger in the correct rotation. But you could case harden them pretty easy if you wanted.

[@makerwright]

Thanks for the video... I have a few questions... roughly how much up/down travel should the plunger have if it's operating correctly? Also, is there a common cause for leaking at the top of the HH? Mine is keeping the top of the HH fairly wet with fuel, but not drenching or spraying everything in the area. The injection lines are dry above the head, and the center plug and lines are torqued tight in the head. Is there a gasket or crush-washer under the center plug that seals the plug? what seals the lines/flare nuts against the head? Thanks again - Maker

[@MVPartStore]

I've seen a lot of heads leak from the injection lines. One thing to try is removing them all and making sure they are clean of any rust or debris. Once there are clean and all the ferrals spin freely reinstall them and make sure they are tight. There are no gaskets in the injection lines. I have to verify there isn't in the center plug but I don't believe there is. There is roughly 3000 psi in that system so placing a washer in the system anywhere would change the volume, however small, and therefore change the psi rating. Movement is about 3/8 of an inch or there abouts. I haven't measured it yet to give you an exact so I'm basing that upon spring compression.

[@makerwright]

Thanks for the info and speedy reply... I'll give that a try. I've also got to replace the gasket on the fuel shut-off cover (leaking oil a bit) would you suggest putting any type of sealant on that screen mesh embedded -looking gasket?

[@MVPartStore]

If the gasket has torn then yes replace it. I would use the gray RTV that is meant for oil contact and not bother with a gasket. Otherwise I have simply reused the gaskets without issue. If you ever need the o-rings for the head I have those available as well.

[@makerwright]

DOH! I just got a new gasket in the mail (Timing is everything) I've got some Permatex "Ultra Black" I'll give that a try. Thanks again. Looking forward to the next vid. - Maker

[@makerwright]

I do want to get a spare set of o-rings and a retainer clip... are the o-rings in the kit nitrile? the MV website didn't specify.

[@conniemccann1343]

Did you start making the butterfly clips?

[@MVPartStore]

I actually sell them on my website now. mvpartstore.com/products/ambac-hydraulic-head-plunger-guide

[@conniemccann1343]

Ok thank you