# Ford NAA Hydraulic issue



## hlbly (Jul 23, 2014)

Hello, I'm a first time poster and a new owner of an NAA. The hydraulics seemed solid when I bought it, but after 4 hours of running a heavy bushhog they seem a bit puny. It has the piston pump rather than the vane pump. Here are the symptoms:

1. It won't hold the bushhog off the ground at low RPM
2. It pulses a little when holding up even lighter things like a PTO driver chipper.
3. Things go to the ground quickly when the motor is turned off.
4. The fluid is a bit milky.

Okay, there is apparently some water in the fluid so I need to flush and replace. Here are my questions:

1. I assume water in the hydraulic fluid is not enough to cause all of these symptoms. Is that correct?
2. Which valve should I look at first? There are no visible leaks. 
3. Can I take off the side cover and look for valve leaks during operation?
4. The image below is a picture of the pump. There seems to be a non-original screw in the top of the pump. Was that a bleed valve originally? If air was getting in there would it cause these issues?

Any help or suggestions greatly appreciated. Thanks!


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## Rustynuts (Sep 13, 2014)

I'm more familiar with Ford Ag tractors but some basics may apply and help you. It sounds very much to me like there's a leak in the hydraulic top cover where you upper lift arms are, under the seat area. You say that the arms b pulse or bounce and this is sign of the system over correcting: in other words the system is trying to maintain the lift height but a leak causes the arms to drop, however linkage recognises this and pushes the control valve in the lift cylinder casting to the raise position and lift the arms back up, if the leak is bad enough, this will happen very often, I've even seen the bounce up and down! 

Again I'm sorry I'm not familiar with what a this FAA? is but on an Ag machine there is a service outlet on the back for lifting tipper trailers or running hyd motors etc, if you get access to a hydraulics gauge and put the right fitting on it ( screw on Dowty type coupling if it's old or a 1/2" quick release if it's younger, stick it in the line and apply pressure through the external service lever, you should get a pressure reading and when I was working on 10 series, this was about 2600 psi. If you don't get pressure then it may be the pump at fault or a dodgy relief valve but if the pressure is there, it's more likely to be a bad leak in the top cover, usually one of the O rings between the lift cylinder casting and the inside upper of the top cover casting. Without knowing more about this machine I don't want to go further and mislead you so try and get a shop manual or the services of a friendly mechanic to help you if your not sure. good Luck!


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