Sos trans over full

cemeyer

Member
Good evening,

I was going to follow the Ford manual to adjust pressures and bands on my 59 981. First step is check oil level. I pulled the plug and it was quite a bit over full. I worried I got water or something in there to cause it, but it was not milky. I then checked the dipstick on the hydraulic reservoir and the it doesn't register. When I used the tractor Saturday, the hydraulic reservoir was to the full mark. So, I think I found where the excess oil came from, but what could have failed to cause it?

Lube tubes? Seal?

I've been having issues of the low lube light coming on only in certain gears, so I was going to run through the adjustments to try and correct the issue.

Thanks for your advice.

Curt
 
Most likely the hydraulic pressure tube in the transmission has perforation holes due to corrosion.

The hydraulic pump them pumps the oil from the hydraulic sump into the transmission.

Dean
 
No need to check. It's a near certainty.

OEM tubes are no longer available but there are aftermarket tubes available.

There are several threads about this issue in the archives.

Dean
 
I searched the archives and found many posts on repair. Thanks.

Does any one make a new tube for the SOS trans or have the measurements so I could have one made before disassembly?
 
I think Walt's has the tubes. My 901 has had the problem for 50 yrs. Been draining excess and putting it
back in hydraulics. Have watched videos of pulling old tube but not sure if I can jut drive new one in.
 
I'm not sure if the tubes in the S-O-S are the same as those in the four and five speed transmissions. Check the online parts listings to find out.

Dean
 
Parts site doesn't even show the tubes for the 4 or 5 speed, at least I can't find them anywhere. But the part number on the tubes listed on hte parts site for the S-O-S show on partspring as being used by 4 speed, 5 speed and S-O-S models.
 
In my parts book, it shows part # 310412 for the sos, NCA-945-B for the 4 speed and NDA-945-B for the five speed.

I think I'll order a stick of 1/2 heavy wall tube from McMaster and pray the existing one comes out in one piece so that I can get measurements to make a new one.
 
Update: I pulled the tube and it looks like its brand new. No rust, no pin holes, no leak as far as I can tell. So, do you think it can be reinstalled? I have my doubts since it is a press fit.

What are your thoughts on the next course of action? Split the trans/reared and change the trans output shaft seal?

I have measurements if someone has dimensions on the 4 and 5 speed to compare it to?

It is 26 5/8" O.A.L.
.500 diameter tube
.505 for .675 on the big end
.487 for 1" on the little end.

It looks pretty simple to make with a lathe to turn down the small end and a ball bearing to swell the big end.
 
I don't understand how a bad trans/pto output seal could cause your symptoms - full fluid levels across the trans/hyd/differential are all the same or nearly so (as I type this I do realize that I've not checked this exactly, but have changed fluids on several 9xx, including my S-O-S and it's got to be very close), there needs to be some mechanism to explain oil being removed from one reservoir and moved to another and a leaky hydraulic pressure tube neatly explains how that could happen -

just to make sure we are all on the same page, you have split the tractor at the bell housing and removed the smaller tube that is sealed by an o-ring at the lower right front of the bell housing and runs into/thru the transmission and is sealed by an o-ring to the rear end housing?
 
(quoted from post at 21:59:14 03/17/17)
Split the trans/reared and change the trans output shaft seal?

No! No! No! You'd be wasting your time and accomplish nothing.

Leaky output shaft or PTO shaft seals on that transmission would overfill the hydraulic reservoir as there is constant transmission lube pressure there.
 
I did not split the tractor. I remove the manifold from the hydraulic pump, tapped the small tube with a 7/16-20 tap, used a fully threaded 7/16 bolt with a spacer and nut as an improvised puller to remove the tube.
 
So if it can't be a seal from trans to rear end housing and the hydraulic tube looks perfect, what else could cause the migrating oil?
 
" I remove the manifold from the hydraulic pump, tapped the small tube with a 7/16-20 tap, used a fully threaded 7/16 bolt with a spacer and nut as an improvised puller to remove the tube."

kudos - smarter than me (altho I've not needed to perform that operation) - did it fight you all the way out? I've wondered how that tube seals where it exits the bell housing/enters the transmission -

I am at a loss to explain how hydraulic fluid could overfill the transmission without that tube being involved -
 
How did the o-rings looked when you pulled the manifold from the front of the transmission, and how tight/hard was the pressure tube to remove? Although I've never heard of it happening this way, if the o-ring was in bad shape and the pressure tube was a loose fit to begin with, the pump could have been pushing some of the fluid around the o-ring and the end of the pipe and directly into the transmission, but it is unlikely unless it was a really loose fit.

Is this tractor new to you? If so, and because the pressure tube looked practically brand new, the previous owner might have tried replacing the tube and not gotten a proper fit when he did it.
 
The longest part of removing the tube was fully threading the 7/16-20 bolt for the "puller". Could not find a bolt suitable at ace hardware last night.

It is tight for about an inch and then you're out of the press fit and it just slides out.
 
I've owned the tractor for 4-5 years. I'm not sure of any history before that. The o-rings looked good, but even if they were bad it would just leak to the floor. The tube is 1/2" diameter and the o-rings sit in a recess that is about an inch in diameter. The only thing that seals the tube inside both ends of the transmission is the press fit. My tube has lateral marks around the whole diameter of both ends of the tube. So it appears like it had complete contact with the bore of the transmission case on both ends.
 
I've owned the tractor for 4-5 years.

So the trans and hydraulics were both working fine for most of that time and the problem just started recently? That's a head scratcher for sure. The only thing that could make the hydraulic sump that low and the trans that high is something pumping the fluid from one sump to the other, as you said that a couple of days of sitting causes the levels in the two sumps to even back out. It sounds like you do have a leaking seal between the two sumps that is causing them to level back out, but the only thing that would normally force the fluid from the hydraulic sump into the trans would be the pressure tube leaking.

Keep us posted on what it turns out to be.. if you ever do figure it out.
 
(quoted from post at 07:35:10 03/19/17)
I've owned the tractor for 4-5 years.

as you said that a couple of days of sitting causes the levels in the two sumps to even back out.

Did I miss something? I do not see anywhere that he said that.

If he did the only explanation is a hole in his tube that he's not seeing and that fluids seek their own level at rest.
 
(quoted from post at 10:16:17 03/19/17)
(quoted from post at 07:35:10 03/19/17)
I've owned the tractor for 4-5 years.

as you said that a couple of days of sitting causes the levels in the two sumps to even back out.

Did I miss something? I do not see anywhere that he said that.

If he did the only explanation is a hole in his tube that he's not seeing and that fluids seek their own level at rest.

Larry - In his first post he said when the trans was overfull the hydraulic sump was so low it didn't register on the dipstick, and then he said:

When I used the tractor Saturday, the hydraulic reservoir was to the full mark. So, I think I found where the excess oil came from

I took that to mean that after it sat and he checked it again on Saturday the hydraulic sump was back up... but reading back on it again, maybe the Saturday that he checked and it was full might have been before the problem happened. Hopefully he'll reply to clarify that for us.
 
(quoted from post at 10:12:01 03/19/17)
(quoted from post at 10:16:17 03/19/17)
(quoted from post at 07:35:10 03/19/17)
I've owned the tractor for 4-5 years.

as you said that a couple of days of sitting causes the levels in the two sumps to even back out.

Did I miss something? I do not see anywhere that he said that.

If he did the only explanation is a hole in his tube that he's not seeing and that fluids seek their own level at rest.

Larry - In his first post he said when the trans was overfull the hydraulic sump was so low it didn't register on the dipstick, and then he said:

When I used the tractor Saturday, the hydraulic reservoir was to the full mark. So, I think I found where the excess oil came from

I took that to mean that after it sat and he checked it again on Saturday the hydraulic sump was back up... but reading back on it again, maybe the Saturday that he checked and it was full might have been before the problem happened. Hopefully he'll reply to clarify that for us.

I could be wrong, but I took that to mean that prior to the time of use, the hydraulic level was fine and that after he used it a little it was low. I didn't take it that it rebounded for him. Perhaps he'll affirm one of us?
 
(quoted from post at 13:13:26 03/19/17)
(quoted from post at 10:12:01 03/19/17)
(quoted from post at 10:16:17 03/19/17)
(quoted from post at 07:35:10 03/19/17)
I've owned the tractor for 4-5 years.

as you said that a couple of days of sitting causes the levels in the two sumps to even back out.

Did I miss something? I do not see anywhere that he said that.

If he did the only explanation is a hole in his tube that he's not seeing and that fluids seek their own level at rest.

Larry - In his first post he said when the trans was overfull the hydraulic sump was so low it didn't register on the dipstick, and then he said:

When I used the tractor Saturday, the hydraulic reservoir was to the full mark. So, I think I found where the excess oil came from

I took that to mean that after it sat and he checked it again on Saturday the hydraulic sump was back up... but reading back on it again, maybe the Saturday that he checked and it was full might have been before the problem happened. Hopefully he'll reply to clarify that for us.

I could be wrong, but I took that to mean that prior to the time of use, the hydraulic level was fine and that after he used it a little it was low. I didn't take it that it rebounded for him. Perhaps he'll affirm one of us?

On Saturday the 11th, before I used the tractor, I checked the dipstick and it registered full. I did not check the transmission.

On Tuesday the 14th, I decided to adjust the pressure valves in the trans to try to remedy the low oil indicator light that comes on in a few gears. This is when I found the hyd fluid low and trans over full.

I hope this clears up the order of stuff.

I found another post in the archives that mentioned the pto seal could be the culprit. Looking in the parts book, it appears the seal is to seal fluid in the transmission not seal in the hydraulic fluid. But it is an illustration and could be a double lip seal. I'll see if I can find a pic of the seal to verify. Part number 312410, I think. The parts book I have doesn't list it in the description. And there's also seal 703 in the same vicinity. Probably going to have to split it to verify. ????
 
(quoted from post at 13:13:26 03/19/17)
(quoted from post at 10:12:01 03/19/17)
(quoted from post at 10:16:17 03/19/17)
(quoted from post at 07:35:10 03/19/17)
I've owned the tractor for 4-5 years.

as you said that a couple of days of sitting causes the levels in the two sumps to even back out.

Did I miss something? I do not see anywhere that he said that.

If he did the only explanation is a hole in his tube that he's not seeing and that fluids seek their own level at rest.

Larry - In his first post he said when the trans was overfull the hydraulic sump was so low it didn't register on the dipstick, and then he said:

When I used the tractor Saturday, the hydraulic reservoir was to the full mark. So, I think I found where the excess oil came from

I took that to mean that after it sat and he checked it again on Saturday the hydraulic sump was back up... but reading back on it again, maybe the Saturday that he checked and it was full might have been before the problem happened. Hopefully he'll reply to clarify that for us.

I could be wrong, but I took that to mean that prior to the time of use, the hydraulic level was fine and that after he used it a little it was low. I didn't take it that it rebounded for him. Perhaps he'll affirm one of us?

On Saturday the 11th, before I used the tractor, I checked the dipstick and it registered full. I did not check the transmission.

On Tuesday the 14th, I decided to adjust the pressure valves in the trans to try to remedy the low oil indicator light that comes on in a few gears. This is when I found the hyd fluid low and trans over full.

I hope this clears up the order of stuff.

I found another post in the archives that mentioned the pto seal could be the culprit. Looking in the parts book, it appears the seal is to seal fluid in the transmission not seal in the hydraulic fluid. But it is an illustration and could be a double lip seal. I'll see if I can find a pic of the seal to verify. Part number 312410, I think. The parts book I have doesn't list it in the description. And there's also seal 703 in the same vicinity. Probably going to have to split it to verify.
 
Is the normal level in the trans that much lower than the normal level in the hydraulic sump? A leaking seal would just cause the fluid to migrate between the two sumps just enough to even the level out between them. I am not sure how high the level check hole is on your S-O-S transmission relative to the full mark on the hydraulic dipstick, but if the level check hole is drastically lower than the full level of the hydraulic sump then I suppose a leaking seal is a possible cause. You could try parking the tractor facing uphill for a couple of days to see if the fluid migrates back.
 

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