Stubborn-4500

I have a 4500 backhoe. Whenever it gets warmed up real good (like when I plow the driveway) it loses all hydraulic power. I let it sit and idle for 15 minutes and it will then work again. If I drive in a higher gear down the highway it will actually start venting by the shifter on the top of the tranny. If you look in there through the fill gap it looks all bubbly when this happens.

What gives?

BelarusBulldog

Sounds like your vents could plugged, and the bubbles might be from the oil getting too hot. Then again, the bubbles could be caused by pump cavitation. Another thing to check is your hydraulic filter, ( might be plugged ) when was the hydraulic oil last changed?

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harry16

My guess is that you have a leaking o-ring at the hydraulic pump suction.

You probably have suction and return filters that need changing as well.

Stubborn-4500

When this first started happening I changed the transmission fluid and the filter. Maybe I only changed one hydraulic filter? I didn't know there were two. I did this in 2007 but it only has about 10-20 hours on it since then. The hydraulic filter I changed is a regular can style filter like a car oil filter. Is that the suction or return filter? Also what is the correct fluid for the transmission? It has New Holland Multi G 134 hydraulic fluid in it right now.

harry16

I checked with Messick's and the Ford 4500 has only one hydraulic filter, as you stated. New Holland Multi G 134 hydraulic fluid should be fine, but the latest fluid specification is 134D.

If you can get to the pump suction connection, put some silicon sealant around it to prevent any air leakage and see if this helps. It normally has an o-ring seal.

It could also be a cracked suction tube.

sixbales

Does your 4500 have a power shift transmission?? Like an SOS transmission - 10 speeds forward and 2 reverse?? When the hydraulics stop working, does the transmission stop working as well??

Stubborn-4500

Where is the pump suction connection located? I need to find an IPL for this things so I can start understanding what goes where.

Stubborn-4500

No, It has a four gear shifter between your legs and and a forward/reverse lever on the area left of the steering wheel. You have to let off the throttle to shift it from one gear to the next and if you are going forward you really have to let it idle way down to get it into reverse without grinding.

Basically the first sign of the transmission problem is it will throttle up but the increase in RPMs does not translate into acceleration and eventually if you try to keep moving it will just quit moving. As for the hydraulics they still work but are slowed down.

sixbales

I obtained the following response from JF in CT:

Does the transmission overheat light (to the left of the Power Reverser lever) light up for self test when the key is turned to the first notch? This system should be working before operating the transmission. There is a pressure test fitting under the access plate on the bottom of the bell housing. I don't remember what it is supposed to read when warmed up. If the pressure reads good when it is slipping then the clutches are probably shot. If the pressure drops off then the pump is probably shot.

As mentioned elsewhere try the fluid first. The hydraulic problem should be something else since the two systems are independent. Maybe the fluid is wrong in both systems.