# Ford 3910 power steering gear box



## dcarter (Dec 24, 2016)

I am trying to change the gear box seals in my 3910. It is leaking pretty bad. I've gotten about 3 hours into the project and I can not get the box apart. Pictures are of the type of gear box I have. I have taken the 6 bolts around the plate off, screwed the screw on this side all the way in and I still can not get it off. Any help is greatly appreciated


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## dcarter (Dec 24, 2016)

Sorry for some reason the picture got turned around.


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## sixbales (May 18, 2011)

Howdy dcarter, welcome to the forum.

Attached is a parts diagram for your gearbox. According to my shop manual, for a similar gearbox, that cover should come right off. Must be stuck in place.


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## dcarter (Dec 24, 2016)

I've tried prying it off but it doesn't want to come off. Is the shaft that goes through it connects to the plate?


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## sixbales (May 18, 2011)

I've posted your problem on the yt tractor forum. Give me a little time to see if they can come up with something. I'll get back with you ASAP.


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## sixbales (May 18, 2011)

Well, no response from the guys on the yt forum. You might consider going to your local New Holland dealership, to see if they will let you look at their service manual. Maybe one of their mechanics has done this before. 

My only concern is that we've overlooked a snap ring on the shaft? 

If you can get the cover separated from the body, you can try a 2 jaw puller bearing against the shaft.


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## dcarter (Dec 24, 2016)

I have went to my parts dealer up the road and asked them and they said it would come straight off. It's not wanting to come off from either side. I didn't see any snap ring when I looked at it. I appreciate your help. I'm going to try and see if I could use a gear puller to get the plate off.


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## deerhide (Oct 20, 2016)

try wiggling the steering wheel when you pry, gently.


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## dcarter (Dec 24, 2016)

My friend wiggled the steering wheel, it helped me get the 2 screws loose. Do the 2 screws have to be completely out in order for the plate to come off? I dont want to damage the shafts because they are very expensive. Im not sure if i can just keep pulling that plate to where it comes off the shaft.


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## TraderMark (Nov 15, 2011)

If you look closely at the parts diagram that sixbales posted you'll see that item #2 is a dowel pin that fits into the body of the steering housing and also into the cover you're trying to remove. The dowel keeps the two parts aligned. Most things that have dowels aligning the two halves do no just slip apart. You'll have to get something (screwdriver. prybar, etc) between the housing and cover close to the dowel pin and pry them apart.

HTH,
Mark


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## dcarter (Dec 24, 2016)

I was able to get the plate away from the box itself. The dowel is still in the box side. Picture #2 kind of shows how far I have gotten the plate off. I havent been able to work on it for a couple days so tomorrow I will try it again. Thank you to all who have helped.


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## dcarter (Dec 24, 2016)

I looked at the diagram sixbales posted again and seen that there are 2 dowels. I only knew of the one that went into the plate and housing which Im assuming is #2. There is another dowel, #29A. Please forgive me for my ignorance in this situation. Im learning as I go


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## fireman9731 (May 4, 2017)

New member here- proud owner of a '89 3910 with a power steering leak. Dcarter, were you able to complete your repairs? I am in the same boat. What I thought would be a simple seal repair has turned into a much bigger job. 
I am trying to replace the steering sector shaft seal (#36 in the diagram that sixbales posted) Its the seal on the left side of the tractor, I have finally gotten the arm off, now I guess I have to pull the cover off of the other side to be able to get the shaft out to replace the seal? 

Once the cover is off, does the steering sector shaft just slide out? Also, when putting everything back together, how tight is the adjuster screw(#22) supposed to be? 

Any help would be appreciated!


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## TraderMark (Nov 15, 2011)

Welcome fireman1!!

I too thought it would be a simple 30 minute task to change the seals in the steering gearbox. While not overly complicated it is a bit more than a 30 minute job.

The cover is on the right side of the tractor. Once you remove both steering arms you'll need to remove the bolts from the cover and completely remove the nut from the adjusting screw. 

Start turning the adjusting screw IN. At some point the adjusting screw will start pushing the cover away from the steering housing. When the cover starts to move you'll need gently wiggle/pry the cover on the end opposite the adjusting screw. (where the steering shaft comes through the cover) There is a dowel pin there that you'll have to work the cover free of. Continue turning the adjusting screw in and wiggling the cover along the shaft until the adjusting screw is free of the cover. You can then remove the cover. The adjusting screw fits into a T slot in the steering shaft, so it may fall out when you remove the cover.

Removing the cover will allow you to replace the oring in the groove inside the steering arm hole.

Once you have the cover off, you can remove the left steering shaft to replace the oring in the housing.

When you start to reassemble the gearbox, you'll have to install the adjusting screw into the T slot in the end of the shaft, then push the screw far enough through the cover and that you can turn the screw OUT to pull the cover on. Make sure you have the dowel lined up. You may have to gently bump that end of the cover to get it to fully seat. 

I would recommend that you use a new gasket and clean both surfaces well. I didn't. So I had the pleasure of doing this a second time to replace the gasket I should have replaced the first time. 

There are also timing marks on the steering valve rack and on the gears of both shafts. Make certain these timing marks are aligned.

HTH,
Mark


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## fireman9731 (May 4, 2017)

Thank you so much! How snug does the adjusting screw need to be upon reassembly?


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## TraderMark (Nov 15, 2011)

There's a whole procedure in the service manual to adjust the two steering shaft/gears. It involves a scale and a rope to measure the amount of force required to move the steering wheel.
However, what I did was:

Loosen both adjusting screws by backing them OUT.
I rocked the steering wheel back and forth and watched the right steering arm as I screwed the adjusting screw in a little at a time. Once I had all the free play out of those two gears, I continued screwing the adjusting screw in until I felt some drag on the steering wheel. I then back the screw out until there was *almost* no drag on the steering wheel and there was no free play at steering arm.

Then I repeated the procedure for the other side. It has worked well so far. It's been about 2 months since I did the repair.

Mark


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## fireman9731 (May 4, 2017)

Thank you again, this place is great! I got the other arm and cover off this evening. Found the culprit o-ring and will stop by the dealer tomorrow to get the correct parts. They originally sold me a seal, there are apparently many different steering boxes on the 3910 and the parts guy had never seen one like ours. One last question- to refill the gearbox, do I just fill it up to the fill hole on the side of the box? And is regular power steering fluid ok or should I use universal hydraulic oil? I have dumped a gallon of automotive power steering fluid into the reservoir at the pump but the fluid that came out of the box smelled oily. Any suggestions?


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## TraderMark (Nov 15, 2011)

There are 3 or 4 different styles of steering gearbox. It pays to be careful when trying to get parts.

I used a hose attached to a funnel to refill my gearbox with UTF. As for the powering steering pump, I use engine oil in the reservoir. That's just my personal preference but sooner or later the front seal in the steering pump will fail and I'd rather have engine oil leaking into the crankcase than ATF or automotive PS fluid.

Mark


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## fireman9731 (May 4, 2017)

The dealer only had one o-ring in stock this morning so I had to hunt down another one. After several stops with no luck, I ended up a hydraulic service shop. It's an odd size apparently. They said it was a 900 series o-ring if that helps anybody. It may have been just a smidge bigger than the genuine one but it fit in the groove just fine. A lot cheaper too!
Anyway, I got everything cleaned up and put back together without too much issue. The dealer said to use hydraulic transmission fluid so I drained the reservoir and refilled it with Ambera and refilled the gearbox too. I must say, the steering is much smoother now. I used to get an occasional binding at full turn, no problems now! I assumed that there was a sharing of fluids between the gear box and the power steering pump. I kept topping off the reservoir, thinking my leak was at the gearbox. There was plenty of fluid in there when I took the cover off. Maybe I have a leak somewhere else.... pretty sure it's not going into the engine oil at least.


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