Deere 401C hydraulic help

ster1 · Dec 26, 2023

Hi folks,
Well I assume my problem is hydraulic. I'm working
on a late '70s (guess) Deere 401C, and when I crank
the engine over with the starter motor, after maybe
20 seconds or so, the starter motor really labors and
cranking RPM drops. Almost like it would act if a
hydraulic circuit were activated. My bucket isn't
moving (controls centered), My lift is down, and the
draft lever is up. I have to admit, I don't understand
how or even what draft is, but the lever was all the
way down, so I moved it up to make a change and no
change happened. Anyway, im wondering if there's
anything else you guys can think of. I'd certainly
appreciate any thoughts. Thank you!

wore out · Dec 26, 2023

It sounds like there's an internal high pressure hydraulic leak so the hydraulic pump doesn't destroke and loads the starter.

Try rocking the steering wheel back and forth repeatedly, from left to right and repeat when this happens and see if this makes a difference. (While this may seem counterintuitive to those more familiar with open center hydraulic systems it DOES usually work on closed-center DEERE hydraulics.)

If doing that helps the leak will need to be tracked down and repaired or a manual or electric/automatic destroker can be installed on the front pump to destroke it during cranking/starting.

ster1 · Dec 26, 2023

Thank you! I didn't even consider the steering. I'll try
it out and post up what I find.

buickanddeere · Dec 26, 2023

http://tractordata.com/industrial-tractors/000/0/1/19-john-deere-401c.html

buickanddeere · Dec 26, 2023

Destroker kit , item #6 is your friend . Along with a block heater and a battery ground update .
The factory connection on the negative side through the sheet metal fails after a few years . Route a heavy cable from the battery negative to a starter mounting bolt .
There is two large batteries in there ? Too often somebody tries their luck with a single medium sized battery .
Use the highest CAA batteries that will squeeze into the battery compartment .

This post was edited by buickanddeere on 12/26/2023 at 07:30 pm.

buickanddeere · Dec 26, 2023

ster1 · Dec 27, 2023

Wow thanks everyone! Based on the number of responses I'm going to guess this topic gets discussed often. Or at least has a history here. I'm a mechanic and work on machinery, but I guess only open center stuff. The only thing I knew about closed center is that they build pressure first and then stop pumping. I never really understood the reasons for that, but mine is not to understand the why, I suppose. So, now your comments about a high pressure leak make sense. I had to think about it for a little while. A destroking valve is appealing to me as a band-aid measure, but I'd like to get to root cause. Only 1 battery. It's a fairly big un though. Anyway, I'm going to take some time and look though all the other posts on this topic (there seems to be a few), before I post any more repeat questions on this one. Thanks again guys!

ster1 · Dec 27, 2023

Well you hit the nail on the head, I think. Yes wiggling
the steering wheel does help, as does using the lift
(until it tops out anyway). And lo and behold, while I
was messing with the engine, I noticed a puddle of oil
under it, right under the steering gear. So, there's a
few things pointing to the issue. I'm trying to get the
engine running well enough to get it into the shop, so
I think for now, I better order that destroking valve,
and fix the hydraulics when it's inside and warm.
Thank you so much for the help!

Deere 401C hydraulic help

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wore out

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buickanddeere

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