1970 Ford 5500 backhoe. I’m basically at my witts end with this machine. it sat for about 15 years with a newer motor with less than 100hrs. I bought it and replaced many hydraulic lines drained fluid and got as much gunk out of the tanks as I could. Cleaned suction strainer. Replaced fluid with J20 Shield and cam 2. Ford recommend a multi-g134. Tractor runs great but you can hear the buzz of the pump aerating. After a few minutes of using the pump will start groaning when using hydraulics then fluid will overflow the breather. Got a new pump(hindsight I would not have). Fluid and pump still was unchanged. I felt maybe I left too much old contaminated fluid in the system so I drained it all again and blew all lines out. Bought 70 more gallons… vacuumed out suction strainer port and cleaned it again. I replaced the cracked rubber boot with a hard 2” elbow brazed. I have t-bolt clamps tight on the suction side with new rubber hose. It makes the noise and aerates immediately so I feel it’s in the suction side but everything is tight. I’ve had grease on each fittings and cannot find where air is getting in. After shutting it off you can hear bubbles every so often. I’m wondering now if maybe the fluid is not compatible with a vane pump. Please help!
You talk about suction strainer cleaning, but did you replace the intake filter on the pump. Sounds like system (pump) is starving for fluid thus the aeration.
Where the suction clamps are..........are those threaded pipe ends?
The only strainer/filter on the suction side between the pump and tank is the one I cleaned. It seems like the original type and I cleaned it well.
No. I ground out threads to receive a 2” pipe and brazed in stainless exhaust pipe.
I would charge the reservoir with at least 15 psi. of air. Maybe, just maybe, the pump would start pulling oil like it should.
I like that idea. While it’s running? Someone, just today told me to charge the reservoir with air and if there’s a leak in the suction line it should push oil out.
Charge the tank and look for leaks. Then start it up and let it idle a few minutes. Work some levers while it is idling. Then leter rip ! Hopefully you will be good to go.
Man I hope so. I’ll try that tomorrow and give an update. Thanks. I’ve been working on this thing since February.
In your opening post you mentioned that you blew all the hydraulic lines out. If you did that with compressed air, that is lot of air for the system to purge. That also would cause the oil to foam for quite a while.
So I pressurized the tanks through the reservoir breather. Felt promising. I had a compression test kit that hooked right into it and to my compressor, set at 15psi. air leaked through the loader lift valve which eventually turned to an oil leak. I suspect the air that came out was from trapped air from popped bubbles. Also oil seeped from the filter cover bolt. Otherwise, no change. You can hear the buzzing noise immediately upon startup so I think I’ll rework my suction line and check the strainer..again. I’m also using a paper type gasket. The typical stuff from the auto parts store. Any issues with that maybe? Still scratching my head. thanks for the help.
If you have a straight edge check the filter flanges.
The OEM and equivalent for that bended hose still available.
As is #56 gasket.
Hey I appreciate that. I got to the gates page before but turned away when I didn’t see anything about it being oil resistant. Probably really doesn’t matter. I’ll go ahead and get one. My homemade elbow is a little cramped.
You is right. Gates is EPDM, and, according to this https://www.wcrp.uk.com/technical/m...lastomer-offers-the-best-oil-fuel-resistance/ it doesn't resist oil well.
Summit racing has a 4 ply silicone one (you may have to shorten it a bit). It says 2" ID each end. https://www.summitracing.com/parts/vpe-2740?rrec=true
Radiator hose swells and get soft before total failure in an oil application. Why Silicone Hoses Cannot Be Used for Oil and Fuel https://www.instructables.com/Why-Silicone-Hoses-Cannot-Be-Used-for-Oil-and-Fuel/
I called the company that I got my new pump from and they think it’s a shaft seal and maybe the bearings that are leaking. I do remember a small amount of play in the shaft when I got it. They’re sending me both so I can install and rule that out. Hopefully that’s what’s leaking so I won’t have to mess with all the fluid again! Out of town for a week so I’ll be back working on it with an update after that.
Absolutely possible. You will be glad to finally solve the mystery I'm sure.