VAC no hydraulics, where to start?

Bret4207 · Oct 16, 2021

My VAC with the pump on the engine, not belt pulley, is full of oil, but the Eagle hitch isn't responding to the lever. Looking in the torque tube the oil is moving which makes me think the pumps working. Do I start at the lift lever looking for broken parts?

Joe (Wa) · Oct 16, 2021

Bret, Approx what year is your VAC?

If the pump pressure is adequate and you don't have a remote cylinder control valve in the pressure line to the hitch control unit block than the problem may be completely blown piston seal or in the control unit block.

I would first check the piston seal. Remove the vent/leak-off line, make sure the fitting in the rockshaft housing is not plugged solid with old grease. There may be some accumulated oil/grease that will drip out. Run the engine and attempt to raise the hitch, the amount of new oil from the fitting is the rate of piston seal leak-bye.

In the control unit block, the problem can be lash adjustment, stuck pressure control valve or the release valve. Can even be the relief valve (plug on the bottom of the control unit block) but it is just a ball and spring. If you determine problem is in the control unit block I can post some pics of how the valves in the unit function.

Bret4207 · Oct 16, 2021

IIRC it's a 53 Joe. Thanks for the ideas. I'll follow up when the rain stops. Where is that diagram from? I haven't seen that before, but all I have is an I+T.

Joe (Wa) · Oct 16, 2021

I have the 1949 and later VA series dealer hydraulic manuals. If the problem is in the control unit I can post pics or loan you the manuals, I want them back as I still use them occasionally.

Joe

Bret4207 · Oct 17, 2021

Thanks Joe. I'll see if I can find those to add to my collection. I wasn't aware they existed. On to Ebay... :lol:

VAC no hydraulics, where to start?

Bret4207

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Joe (Wa)

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Bret4207

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Joe (Wa)

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Bret4207

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