1975 MF 40 starting issues

moose643

New User
Hello all, I was hoping I could get a little help. I have a 3cyl
gas1975 MF40 with an instant reverse transmission that died on
me a few years ago and I have only recently been able to find
the time to try to get it back up and running. Fluids are good and
she has spark / a brand new battery. I replaced/cleaned up the
wiring and had the starter looked at, which was given a clean bill
of health. When I attempt to start it she gets a few good
revolutions then slows down to a stop almost like the battery is
dead. I get this even when I hook the battery up to my truck. I did
notice that it seems to be building hydraulic pressure as soon as
it starts cranking, which I relieve by dropping the bucket. Is there
a way to keep the hydraulic pump from building pressure to let
the starter do its thing? or does anyone have any other
suggestions?

Much appreciated
 
Voltage is good to the starter, but I have a new battery disconnect coming soon. It doesnt seem to work well after pulling the cables and cleaning the connections. However, I will try to perform another voltage drop test once thats installed. Hoping it was the issue but Im running out of options.
 
I havent bypassed the disconnect yet but before I messed with it, it seemed to be working fine. However I got a new one today and will try to report back tomorrow. Thank you
 
A little bit of an update today. I put new ring terminals on the battery cables and cleaned any corrosion I saw. I also installed the new battery disconnect which is much better than the old one. Im getting no resistance from the negative terminal to the grounding bolt on the frame which i am happy with. I started cranking the engine and noticed the hydraulic pressure building. Once the pressure got over 1000psi, the starter would slow to a crawl. If I raised the front bucket as The starter cranked, it would not slow down. So, I was wondering if there was some sort of hydraulic disconnect to keep pressure from building before the motor turns over. Also, if memory serves me, the last time it ran, when it died, it leaked a bunch of hydraulic fluid. Thank you!
 

From you description, I would say you have an issue in the hydraulic system. An open center system should not be building pressure until a valve control lever is operated. Check to see that you don't have a function that the valve spool is not centering on.
 
That sounds plausible. I know that the backhoe boom arm would
start to slowly build pressure as the starter cranked, even though
the lever was dead center. Thinking there may be a leak. Ill try
to disconnect the attachment and see what happens. Thank you.
 
(quoted from post at 18:38:47 08/07/21) That sounds plausible. I know that the backhoe boom arm would
start to slowly build pressure as the starter cranked, even though
the lever was dead center. Thinking there may be a leak. Ill try
to disconnect the attachment and see what happens. Thank you.

Levers may be centered, but if the centering spring arrangement on the spool itself is broken, it may not be centered. Do the levers have a lot of play when working functions? A spool could be worn, or damaged, even broken. If you unhook things be sure not to just plug lines without confirm oil from the pump has an unrestricted return to the reservoir. Deadheading can blow pump seals or even split the pump housing.
 
You all are awesome! I disconnected the backhoe attachment and looped the hydraulic lines. I didnt get her running yet but the starter had no problem spinning the motor and gave me some promising signs when I sprayed her down with ether. I connected the gas line back up and had it spewing out of the intake. guess I need a carb rebuild. Anyone know of a good one? Also, how much trouble is it to rebuild the backhoe spools? I am a complete amateur when it comes to hydraulics.

Thank you thank you thank you
 

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