Memory Check - M35 Multifuel HH replacement

[Miltrucks]

Just looking for a memory check here as it has been 7-8 years since I had to work on a deuce multifuel IP...

Short story - helping my dad here who had a tired motor, clutch, etc. in the Farm truck. We had a good nice running (8-10 years ago, but sealed) powerplant put back as a spare and just did a swap and changed it out with the old truck motor.

Had issues getting fuel past the IP. Fiddled with the HH a bit and realized piston stuck and button off. Changed out the HH with the one from the running unit and now get fuel up to all injectors - all good.

Problem is that it will not fire. Now either all 6 injectors are blocked (stopped late on this last night so haven't checked them) - or more probable, it sounds that the timing is off.

IP wasn't changed, just the HH so believe timing should still be good.

THis is where the memory check comes in. I *think* it was the deuce multifuel where the HH rotated around twice for ever rotation of the engine. If new engine was one rotation, and donor engine was 2nd rotation, I think to remember that the HH would then be out of sync by 180 deg which could cause the timing issue. Solution was to just remove the IP pump and rotate the gear one revolution and re-install to bring back into time.

Does that sound the right logic? or am I confusing this with another military engine from the past? I didn't pull the covers to check the alignment of everything to verify that yet - and probably the next step, but just trying to check if I remember this correctly.

Thanks,

Eric. (aka Miltrucks)

 

[M35A2-AZ]

I am thinking the motor turns over two times for every rotation of the HH. So you could have the motor 180 degrees out of time. Put #1 Cyl. on TBC with the valves closed and the timing pointer should lined up on the front. Then you can set the IP pump. I think that is the way to do it.

 

[gimpyrobb]

Good to see you stopping back in Eric!
Have you tried a quick whiff of ether? I often need to do that to get them to light off once the fuel system has been apart. It should start fine on its own after that.

 

[Miltrucks]

M35A2-AZ - thanks, so I must had it remembered backwards. I didn't remove the IP pump, so assuming it would be still in time as it was previously - I just changed out the HH, and did double check the line order as well - so not getting any fire at all - that why I thought initially timing in the HH position difference. I'll pull and check the actual timing on the motor on Monday. Have to say, this one has me puzzled a bit.


Gimpyrobb - Good to see you still on - was wondering if some of the old crew were still active. Already tried the ether trick. It will fire (but doesn't sound great) as long as it gets the ether shot, but as soon as that's gone, it's dead again. I guess I'll also have to pull the injectors to make sure I'm getting the fuel misted through them.

While I have gotten rid of most of the trucks (there are a few in museums around the country), we still use the dump deuce conversion around the farm and have a 1031 and two 1028s Dad uses for random work. I only have the last one I built - the USAF Suburban (real deal, not one of the conversions) that slowly keeps getting upgraded. It's the dump deuce that was getting the re-engine as it was just getting plain worn out!

 

[gimpyrobb]

If you line up the mark on the harmonic balancer and the advance unit in front of the hyd head, and the red scored tooth is visible(only visible, not lined up), and the valves on cyl one are closed, your good to go.

 

[Miltrucks]

Well, unfortunately after checking things out today, everything was in time, and swapped in known good injectors and still no-go. Now seems to have lighter fuel pressure at injectors again but haven't officially measured. Thinking more may be wrong with the IP from sitting. Going to give it a good soak through, but thinking that replacing the entire IP assembly may end up being in my near future

Not sure what the market on these looks like nowadays, but if anyone has any good leads on new/used out there?

Eric (aka Miltrucks)

 

[rustystud]

Just for grins and giggles, how much fuel is getting to the injection pump ? Could your filters be plugged ? Or your injection pump "boost pump" be plugged ? I would check out those things before I replaced the whole injection pump.

 

[Miltrucks]

Yeah - I have great supply to the IP. New in tank pump, flushed lines, new primary and secondary filters, etc. It's from the pump up that we have issues. I was getting fuel to all injectors, then after a bit, it seems to some of them a bit weaker flow. It's possible that the HH I pulled from the running motor is starting to go and need to put on another HH as well I guess.

Already checked the boost pump as well and didn't see anything that would impact.

I am going to pull everything thing I can off of it in terms of covers / access points, and just soak it all down good for a couple days to see if that frees up anything that might be gummed up.

This is one the pumps without the FDC on it, so probably pull that cover off and dig around as well.



As always, appreciate the advice and suggestions. Things are slowly coming back to me.

Eric. (aka Miltrucks)

 

[rustystud]

Your linkage could be binding up a bit. Have you taken the side cover off and looked at it ? That's also not a bad idea to take the back over off and hosing down the governor linkage with some lubricating spray.

 

[Jeepsinker]

If you tightened the fuel lever bridge too much, the fuel lever may be sticking in the shutdown position.