[AT] OT(?) Cub Cadet 1812 Hydro question

[Stephen Offiler]

Hi SteveW:

Thanks for the inputs; I appreciate it.  Everybody is telling me they
are PRV's.  It's the shop manual that is calling them "check valves";
wouldn't they know?  They appear to function as I'd expect a
check-valve... the spring pressure on the ball is pretty light, so
it'll flow pretty easily with a small pressure differential in one
direction, and close up tight going back the other way.  I'd expect a
PRV to have a much heavier spring, and to hold closed until the
setpoint is reached.  My problem valve, PRV or not, is located in a
port on the pump that leads directly to a line to a distribution
block, and thus appears that they must normally flow in order to
pressurize that block.  I guess my point is that, while hydraulics are
NOT one of my specialties, these things do appear to me to be
check-valves.  I think perhaps the saving grace in the distinction
between the two types of valves is that this spring is pretty light,
so I probably have a shot at getting it back together, whereas a heavy
spring would be a bigger struggle.    And to think...  at first I was
so pleased to learn how easy it was to access the area, and the
specific component, that was the root cause of my mystery leak...

Best regards,
SteveO.

On Mon, Jun 1, 2009 at 11:11 AM, Steve W. <falcon at telenet.net> wrote:
> Stephen Offiler wrote:
>> OK, it's not an antique farm tractor, guilty as charged.  It is a 1988
>> Cub Cadet (MTD built, a.k.a. "Cub Cadet Corp.") and it is a Model
>> 1812, which is built off the same tooling as a real IH Cub Cadet Model
>> 782 or so I am told.  I know all about the "IHCubCadet" online forum,
>> but nonetheless figured I'd start here on ATIS.  My goal is simply to
>> repair this machine so I can make the call whether I want to keep it
>> and mow with it, or sell it and buy a modern Zero-Turn-Radius mower.
>>
>> The basic problem is a leak from the hydraulic system.  It was serious
>> enough (say a quart every 15-30 minutes into the cake pan that I was
>> forced to rig underneath the machine) that I parked it a couple years
>> ago, and here I am today, living proof that occasionally you DO get
>> that Round Tuit.
>>
>> I've got the factory service manual, and it tells me I've got the
>> Sundstrand hydrostatic transmission.  With the sheetmetal stripped
>> from the steering wheel back, a good power-washing and running off a
>> remote battery connected with jumper cables, I found the source of the
>> leak, and mercifully it looks like something REALLY simple.  The pump
>> has two check valves threaded right into the top, very easy to access
>> with no further disassembly.  They are identical, and they each have a
>> tiny vent hole centered in the top.  The leak comes from this vent
>> hole.  The book says these valves cannot be serviced beyond
>> replacement of the o-rings, and removal and inspection of the faulty
>> valve shows that it is crimped together and cannot come apart, so I
>> agree with the book.
>>
>> My specific question is this:  if the check valve is leaking out the
>> tiny vent-hole in the top, does that mean O-ring replacement, or do I
>> need to chase down a whole new valve?
>>
>>
>> Thanks and best regards,
>> Steve O.
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>>
>>
>
> Steve,
>  Sorry to be the bearer of bad news but those valves are pressure relief
> valves. Not possible to rebuild them. When they leak it means the
> internal seal is bad. I have had some luck taking them apart and soaking
> them in some cleaner.
>
> Oh and if you have any other questions try
>
> http://www.ihregistry.com/
>
> We welcome ALL of the CC tractors from the originals on up to todays models.
> Also have LOT'S of guys with spare parts and new parts as well.
>
>
> --
> Steve Williams
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>