Sudden Leak

marimus · Aug 5, 2007

Hello,
I have a NH TT75 which yesterday started leaking hydraulic fluid.
I don't know much about hydraulics (or tractors for that matter), but looking through some loader valve parts manuals (not for my tractor, but to figure out the names of the parts).

Anyway, its leaking from between the body of the loader valve, and the "spool attachment"?. Its one of two cylindrical things bolted to the bottom of the loader valve. The tractor has just over 100hours, and it just started leaking with no load or work being done.

I'm going to call the dealer tomorrow, but I wanted to get a feel for what could have caused this problem, and if it could be a warranty fix, or could it be a symptom of some other (possibly major?) problem?

Any thoughts welcome,

Cran

MJPetersen · Aug 5, 2007

g'day mate. I am trying to get a picture from your description and I believe that what you are refering to are the covers over the end of the spools. I would think that a leak in this area would be covered under warranty. It is probably an o-ring that cracked. You will not want a repeat so Check carefully why?

Mike

marimus · Aug 5, 2007

MJPetersen said:
g'day mate. I am trying to get a picture from your description and I believe that what you are refering to are the covers over the end of the spools. I would think that a leak in this area would be covered under warranty. It is probably an o-ring that cracked. You will not want a repeat so Check carefully why?

Mike

Here is a picture, its not exactly the same as mine, but it illustrates it pretty well. The leak is on one of the two highlighted parts, and its coming from between the base of the part and the housing.

Cran

RonMar · Aug 5, 2007

Based on that location, I would say that it is probably a spool end "O" ring. The "O" ring itself is about a $0.15 part. Changing it out on a joystick valve is a little more involved than a separate lever valve, but still should only take about 1/2 hour or so. Internal valve designs on these small valves are pretty similar. The outer ends of the spools are usually where the return galleries are located. There is an "O" ring at each end of the spool to contain any of this return oil from leaking where yours is leaking. Because there are "O" rings here against the moving spools, they wear. Any dirt in these areas or machining flaws on the spools might also speed a failure. Also because of this the return pressure is limited to a certain PSI(usually in the low hundreds). If for some reason there is some restriction in the return line, this could cause the pressure to build and force oil past the "O" rings.

MJPetersen · Aug 5, 2007

I forgot to add what Ron has now said and that is you must watch the return oil pressure, because that is a very common way these seals are damaged. Sometimes through faulty connecting a QD.

Mike

marimus · Aug 6, 2007

Hi,

Thanks for your replies. I called the dealer, and he said the same thing about the O rings. He is going to send me a set, hopefully an easy fix. He also said that he would send me a new spool if it turned out there was anything wrong with it, so I'm pretty happy.

Thanks again,

Cran

marimus · Aug 11, 2007

O rings arrived yesterday, not that I didn't try and find some from many many other places. Nobody had the right size

Anyway, here is a pic of the spool, with a new oring, and the old one beside it.

This one has always been a little "stiff", and I now realise that the cover was screwed down too far on one side, before the other, causing the spool to rub to one side of the oring.

Since I replaced it, its as smooth as silk.

Cran

MJPetersen · Aug 11, 2007

Hooray!! I always love a happy ending!

Mike

3RRL · Aug 11, 2007

That just goes to show you that Ron really knows his stuff. I find his posts are always informative and pretty much right on the money. I would check your strainer though, in case there is any residual piece of "O" ring that may have sheared off. Don't want that floating around in the system either.