Deere 401B Hydraulic Loss

DernHumpus

New User
I bought a 401B a few months ago and after about the first few hours of operation I have started experiencing stuttering hydraulics. This is occurring in seemingly random locations, from steering, 3pt, to the loader and sometimes it loses ability to move. This also occurs with the loader removed.

The previous owner said he had put a high pressure pump in it, so I contacted him. He suggested I try a hydraulic filter. This seemed to fix it, but I also installed it when the tractor was cold. (and I have done this a few times assuming I was plugging filters since it is easy and cheap and the brake linings are known to come apart and plug filters).

Now that it is hot out this has started to happen more and more frequently, and closer and closer to the time that I first start the tractor. I did quite a bit of reading today on "sister" tractors - I think the 2630 would share symptoms, and here are my other observations:

1. Used hydraulic filter is clean. I only cut open one because it was a PITA.
2. No spray or mist observed through the 3-pt oil fill cap
3. Transmission strainer is clean
4. New transmission oil (about 5 gallons came out and was replaced)
5. Today, I installed a pressure gauge at the oil filter housing, I think downstream of the filter, but after a few minutes of operation it dropped from 200 to 100 psi and the hydraulics quit working. Usually if you shut the tractor off and restart it the hydraulics work for a short period, say, long enough to limp it into the barn.

Now, I am about 80% sure it is the low pressure pump. Does anyone have any comments, input, or support before I go ahead and split the tractor?

Shouldn't my pressure relief be set to 150 psi and not 200 psi? I am suspect the previous owner knew he mis-diagnosed the high pressure pump and sent it down the road.

Thanks,
Dan
 

Welcome to YT
Trans pump pressure should be 155-165 psi. Do hyd operate the same with reverser in both fwd & reverse. Cap supply line to power steering valve then operate to see if hyd's are better.
 
Trans pressure is dropping to 100 psi after a few minutes of operation with ambient temperature around 90F.

When the tractor stops moving, I try the other direction, and it never works. So from what I can tell it is losing both directions at the same time.

Is the steering valve what is just ahead of the shift levers, or do I need to take something apart to feel its temperature? When it stopped moving yesterday I felt the part I could get to right ahead of the shifters and it was barely warm at all. I read that if the O-rings are leaking it would get hot.
 

If tractor stops moving both fwd & reverse then something is causing lose of trans pump pressure. Have you checked to be sure hyd filter relief valve isn't stuck open?
 
No, I have not. How do I do that?

Do my symptoms not point to a worn transmission pump, or are you just trying to help me cover all of my basis before splitting it?

Thanks for the help!
 

Closed center hyd systems such as your 401B need very good diagnostics performed before tractor is split. Many hyd pumps have been replaced only to find out that pump wasn't the problem. Hyd filter relief valve(keys 4-6) is located close to hyd filter.

49541.jpg
 
Ok, pulled it out, I wasn't sure what to expect for the pins, and ended up not having what it took to get the roll pins out.

However, the seat seemed fine, spring wasn't broken, and seemed to have enough pressure. I think the manual says it should have around 10 lbs of pressure when compressed.

Any other thoughts?

Thanks
 
(quoted from post at 13:10:40 06/09/17) Ok, pulled it out, I wasn't sure what to expect for the pins, and ended up not having what it took to get the roll pins out.

However, the seat seemed fine, spring wasn't broken, and seemed to have enough pressure. I think the manual says it should have around 10 lbs of pressure when compressed.

Any other thoughts?

Thanks
worked on a 410 Backhoe years ago.Sound like same thing oil getting warm up loose or slow hydraulics. Check out good when cold .would push dirt/ spin wheels, loader worked good .The loader up -down worded good .Run it about 1/2 hr oil temp up everything slowed down . Did test front pump psi good .sounds like transmission pump wore .
 
(quoted from post at 07:52:34 06/13/17)
Well, it is on its way apart. Surprisingly friendly to split so far...

Well-- I made an assumption and was wrong. I split it at the clutch housing. Do I need to "double split" this or should I put the clutch housing back together and take it apart behind the gear levers?

Thanks-
Dan
 

What I call the clutch and trans housing is one casting. I think the trans needs to come loose from the rear end, behind the shift levers.

The manual is extremely good at being vague.
 
(quoted from post at 13:05:28 06/14/17)
What I call the clutch and trans housing is one casting.


JD engineers & parts catalog authors called housing in photo simply a clutch housing

49703.jpg


JD engineers & parts catalog authors called this part a trans case which contain the trans gears/shaft plus differential.

49704.jpg
 
(quoted from post at 01:47:56 06/15/17) Aaand... transmission pump looks pristine.

Suspected lines are behind it, correct?
When you say pristine (Is that buy looking at pump ) you may need some tech info SPECS . Start mike-ing pump parts for wore out parts. This tractor is a industrial wright ? & fractory loader ? I'm only asking did you do any dioxides before stripping down ? I thought you mention it has a loader , Like feeling w/ hand on in oil return line leaving control valve box on loader if it's getting hot after you start tractor should stay cool 15/30 minutes if no internal leak in valve box.
 

There is no knife edging of any of the gears, no pitting on the gears, no wear to the housing.

The tractor has a 48 loader. The problem is occurring with and without the loader and valve on the tractor.
 
(quoted from post at 13:23:11 06/15/17)
There is no knife edging of any of the gears, no pitting on the gears, no wear to the housing.

The tractor has a 48 loader. The problem is occurring with and without the loader and valve on the tractor.
Check width of gears, (any side play with gears in housing )? With loader off tractor does valve box stay on tractor ? Is tractor equip w/pto? You hav a tec manual right . I'm thinking !! If pumps off can you make a plate to add air PSI like 20-50 psi see if hear leaks after pump . While pumps off ,start eliminating possible leaks ,line ,o-rings , hang in there it's probably somethings simple.
 

Yea, the valve comes off with the loader.

Is losing transmission pump pressure indicative of a low pressure side issue, or could it be a leak on the high side (steering valve) starving the low pressure of flow?
 

Loosing trans pump pressure could be caused by low or high side. Closed-center hyd problems require very good diagnostic procedures to determine the problem.
 

Yea, I keep seeing this, I guess I was convinced by the symptoms I have seen.

What would you recommend next, and what tubes should I be paying special attention to while I am in here?

Thanks,
Dan
 

Reverser oil supply tubes & tube seals have a history of leaking. Does your tractor have hyd ind pto? If so those associated tubes & seals have a history of leaking also.
 
(quoted from post at 19:29:01 06/15/17)
Yea, I keep seeing this, I guess I was convinced by the symptoms I have seen.

What would you recommend next, and what tubes should I be paying special attention to while I am in here?

Thanks,
Dan
If your in trans & ( pump) look it over good . I may have miss spoke about lines, - o-rings ,gaskets ,etc . Tx Jim right 1 leak a o-ring gasket can cause low psi / volume of oil , I have payed my self twice more then once to fine out it was something else was in play and look all the money $ made. No extra $ . I had other info but phone died . Close center Hydraulic = like a house water system you open bath foset water comes out . Water come out at all parts of house .Now have a leak down or upstairs and try to take shower & kids out side w/ hose running you'll loose psi & volume . You now know what's the trans pump looks like . Some check that off the list of possible .
 
Ok, finally got some professional opinion here once I got frustrated.

The reverser clutch housing is worn out. The piston cannot seal. The o-rings and tubes are fine. Pretty much needs a new reverser assembly.

Source?
 

OR, is there an entire "clutch housing" that will bolt into my tractor, maybe one that doesn't have the hydraulic reverser? 2630?
 

Here's the PN listed for clutch housing in 401B PC for tractor less reverser. I'm sure there may be other clutch housing that will fit but would require research to verify

mvphoto1549.png
 

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