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Discussion Starter · #1 ·
So I decided to fix up my Cub Cadet 680 because I am in need of a heavy duty tractor for dragging junk mowers and stuff. The hydro leaks oil through one of the check valves (According to Sundstrand service manual that I downloaded that is what there called). The hydro is almost out of oil at this point and acts like it too. So it's not overfilled. Can I just replace the check valve to stop the leakage or does this point to a deeper problem. Thanks!

The check valve on the right in the photo leaks oil severely through the little
Food Amber Cuisine Ingredient Dish

hole on top.
 

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1976 Sears SS16, 2008 JD 2320
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Hard to say if anything else is wrong. Those check valves can be expensive but you may be able to get a good used one from a tractor recycler. I believe there is also someone out there who rebuilds them but below is a link to a video on how to rebuild them. They are not that complicated. I had trouble with one of them on a JD 317 and I was able to get the valve moving again by lubricating the piston and cleaning the corrosion off of the top part of it. I didn’t need to take it apart.
You also might want to clean the hydro after you get the leak fixed. It may be running hot due to lack of cooling from the fins and the body due to the coating of oil and dirt etc.
 

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Discussion Starter · #3 ·
Hard to say if anything else is wrong. Those check valves can be expensive but you may be able to get a good used one from a tractor recycler. I believe there is also someone out there who rebuilds them but below is a link to a video on how to rebuild them. They are not that complicated. I had trouble with one of them on a JD 317 and I was able to get the valve moving again by lubricating the piston and cleaning the corrosion off of the top part of it. I didn’t need to take it apart.
You also might want to clean the hydro after you get the leak fixed. It may be running hot due to lack of cooling from the fins and the body due to the coating of oil and dirt etc.
Thank you for the reply! Seems like the check valves usually have a little thing on the top like some kind of plug, where there is a hole on mine. Seems kinda strange. I'll probably try cleaning the valve first, and while I have the fender pan off I'll clean the hydro a bit too.
 

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They're the same on many brands that use this sunstrand hydro unit. I put some from a spare hydro i pulled from an ariens, to get a cub cadet going.
There's a guy who offers a rebuild service on these check valves, seems last time I had a pair done by him were something like $40 each. This was like a year and a half ago, his prices might have changed since then. I know he lists his service on eBay, sunstrand hydro check valve rebuild service. I know that he advertises on the cub cadet specific forums.
 

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Thank you for the reply! Seems like the check valves usually have a little thing on the top like some kind of plug, where there is a hole on mine. Seems kinda strange. I'll probably try cleaning the valve first, and while I have the fender pan off I'll clean the hydro a bit too.
There are two different styles of them. The manual ones with the buttons on top that you would push down, or the automatic ones like you have. Either style will work, the automatics are the more common replacement and are still available new, but they are expensive.
 
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