Hydraulic lift problem

[feg7846]

I acquired a 1947 cub from a friend. It set out in the weather for about 5 years. Got it converted to 121v alternator. Running great.
I drained the hydraulic fluid and refilled with MS 1209 which is compatable with Hytran. As per the manual, cycled the lift about 15-20 times to release any air in the system and refilled tank. Lift worked fine for a few days. Yesterday, the lift started a jerking up and down motion when the lift handle was set it most any position. I would let the lift down a ways and it would start jumping up and down. Or, up and the same thing would happen.
Looking for help and advice from any hydraulic heroes out there. Thank you very much....

[Don McCombs]

Check the fluid level again. If it is low, check the engine oil level. If it is overfull, you have a pump shaft seal leak.

[feg7846]

Got her fixed. I was not taking the time to refill the reservoir when I moved the lever forward and backward.
Hydraulics working good since I did it right. I should read the manual before every job, but I don't. In too big of
a hurry. Thanks for your input Bob.

[Bob McCarty]

It would still be a good idea to check the oil level on the dipstick as Don suggested, if you didn't already.

[Glen]

Hi,
Be sure to fill the system to the plug hole, with the arms in the rear, or down position.
The fluid level rises in the unit as the arms go the the rear position.
If you fill it with the arms ahead, it will have too much fluid in it.
If you filled it with the arms ahead, I would remove the plug, run the engine and move the arms to the rear, and let the excess fluid run out.

If you are just checking the fluid level, check it with the arms in the rear position also.