312-H...my hydro finally gave up the ghost.

[calibear2003 4]

Help is needed here!!! I have a 1990 312-H and the Eaton 1100 series hydro has been showing signs of much better days since I purchased it 2 years ago. It currenly has almost 1300 hours on the clock. While cutting my lawn this past Saturday, I was barely able to make up my tiny hill...if only I could cut in reverse because it cruises going backwards. I have been watching my local CL and Ebay, but I have not seen any good used hydro's. I live in the Toledo Ohio area, can anyone point me to a place for a pump rebuild?? Also, would anyone happened to have an extra Eaton 1100 series pump with low hours that I could take off your hands???? I am afraid to even think what the repair $$$ might be to even have the pump rebuilt.

Thanks in advance...

Mark~

[canam1991 2]

i have a rear end out of a 91 312 im in jackson michigan not to far

[calibear2003 4]

Hello,

Is your rear an Eaton 1100 hydro or the 8sp sir??

Thanks.

[calibear2003 4]

No disrespect, I thought the 312-H was produced for the 1990 model year only. I am however wrong all the time lol...

[canam1991 2]

it is a hydro, 312 is a great tractor many many made

[calibear2003 4]

I just sent you a message regarding your hydro.....Thanks..

[312Hydro 474]

Are you sure it's not a linkage problem? It can be adjusted at the cam under the seat and the linkage rods may need it too. Just my .02 . IMHO if the pump was bad you shouldn't have reverse either. I'm sure there are some Eaton 1100 experts here that can help you better than I. Ive always had too adjust the cam when it wouldn't move properly. Here is a pic showing the cam and linkage.

[calibear2003 4]

Yes sir, I have checked and rechecked the linkage and cam adjustment. Sadly to say, I believe the pump is done at least for the forward motion.

Thanks.

[Sparky-(Admin) 21,405]

I hate to ask but how old is the tranny fluid and the filter? Is the level up to the top?

Mike.............

[calibear2003 4]

Hello,

I have owned the machine for the past two years, but it was used only last summer and up until now for cutting the lawn only. I had the same issue last summer, so i changed the filter for a proper hydro filter. I am not sure if the Fram filter that i removed was the proper type of filter, so it was replaced. The fluid looks fresh and new......as in, if inchanged it again, it would look the same. The level is up and at the correct full level. I purchased the machine from a fellow Red Square member who's passion is/was to buy, restore and sell the machines. I did wonder if the seller knew the hydro was tired when he sold it to me.

[can whlvr 993]

the 312-h was made for 90,91 92

[Docwheelhorse 2,682]

I have a similar problem in an 857 (Sundstrand)... it goes like crazy in forwards and has all sorts of power in forwards... but is gutless and the smallest incline stops it dead in reverse... I was speaking to other members at the show and they said that the pressure could be by-passing inside the trans and if you use common sense it seems plausible---if the tractor goes like crazy in one direction then theres gotta be something wrong with the linkage/valves/bypass stuff. But not the pump itself---I know you have an Eaton but they have to have similar setups once beyond the pump itself.

Tony

[JamesBe1 82]

From what little I know of hydro systems, if you have proper functioning in one direction, and not in the other, that would indicate that the pump and motor are ok. That is to say, if the pump was not making the appropriate pressure, then both forward and reverse would both be affected.

The problem is likely with the acceleration valve or linkage. If it is the acceleration valve, then technically it is still part of the pump, but not the portion that creates the drive pressure, but the portion that meters it out to the hydro motor.

I hope I didn't explain that too poorly (it's late here).

This thread has some great info on how hydro systems work. It's D-series stuff, but the hydro systems are basically the same:

[calibear2003 4]

I just found a thread that in detail broke down the Eaton 1100 series hydro pump. However, it did not state which were the common wear parts. It does not look difficult at all, but what/which parts are to be replaced??? Thank you to everyone who read and replied to my post. I learn something new each and every day.

[kpinnc 12,506]

Two things first before you open that pump: Use a large rubber band to hold the ball pistons in the ports (pump AND rotor sides) before they fall out. They are matched in the ports and the pump will be useless if you mismatch them.

And also make sure you keep the work area "surgery level" clean. Any contamination spells the end for these pumps, which is usually the culprit when they fail anyway...

I pressure wash any transmission I plan to open up beforehand- even before removing the pump itself. No super-high pressure, but just maybe a good degreaser and a car wash.

Good luck!

[mattd860 162]

From what little I know of hydro systems, if you have proper functioning in one direction, and not in the other, that would indicate that the pump and motor are ok. That is to say, if the pump was not making the appropriate pressure, then both forward and reverse would both be affected.

The problem is likely with the acceleration valve or linkage. If it is the acceleration valve, then technically it is still part of the pump, but not the portion that creates the drive pressure, but the portion that meters it out to the hydro motor.

I hope I didn't explain that too poorly (it's late here).

This thread has some great info on how hydro systems work. It's D-series stuff, but the hydro systems are basically the same:

Can the acceleration valve be replaced? I have a eaton 1100 that went in reverse and built enough pressure to raise/lower the lift cylinder but would not go forward at all. I've since replaced the pump with a spare out of a 520h but I still have the old pump sitting on my bench and I've been temped to open it up and tinker with it.

[JamesBe1 82]

From what little I know of hydro systems, if you have proper functioning in one direction, and not in the other, that would indicate that the pump and motor are ok. That is to say, if the pump was not making the appropriate pressure, then both forward and reverse would both be affected.

The problem is likely with the acceleration valve or linkage. If it is the acceleration valve, then technically it is still part of the pump, but not the portion that creates the drive pressure, but the portion that meters it out to the hydro motor.

I hope I didn't explain that too poorly (it's late here).

This thread has some great info on how hydro systems work. It's D-series stuff, but the hydro systems are basically the same:

Can the acceleration valve be replaced? I have a eaton 1100 that went in reverse and built enough pressure to raise/lower the lift cylinder but would not go forward at all. I've since replaced the pump with a spare out of a 520h but I still have the old pump sitting on my bench and I've been temped to open it up and tinker with it.

Good question. It more than likely can be replaced if the parts are available. That's usually half the battle - finding the parts (at a reasonable price). IMHO, it's worth the effort to take it apart. You might find some grit or blockage that is causing the problem, or something else. A word of caution - cleanliness is a must when working on hydro pumps and motors.

If you do take it apart, it would be great if you could post some pics of the process. I'm sure many here would like to see them.