1987 755b Hydraulic Help Needed

[8NAcres]

Posting this for my father-in-law, so some terminology my be a bit off. He has a 755b that sat for quite some time and he decided he needed it again for some dirt work. Unknown to him at the time there was a fair amount of water in the hydraulic sump and when he got it running he cycled through the lift, loader, bucket, swing, etc. to verify all was well. Nothing seemed to work so he checked the hydraulic level and he discovered the water. He drained the hydraulic oil, put a new filter on, and tried it again. Now, the boom and outrigger works, the backhoe only works if you hold the boom control activated solidly, and the bucket does not work at all no matter what.

He pulled the main valve to clean it up and replaced the o-ring and a plastic (may not be the right material) ring that was cracked. This did not change anything. Hoping to find some knowledgeable folks that may know a few things for him to check to get this tractor running again. He is very well versed and experienced at heavy machinery repair and maintenance (has done most of his own work for several decades) - me, not so much so I got the research side of things.

TIA

Dan

 

[Leejohn]

What is a 755B?

 

[Xfaxman]

What is a 755B?

I don't know either, but it was made in 1987. :thumbsup:

 

[8NAcres]

It is a heavy construction backhoe loader tractor built by Ford from 1983 - 1988 I believe. 16k lbs and about 100hp. A Google search will show you the full spects from tractordata.com:

TractorData.com Ford 755 backhoe-loader tractor information

Dan

 

[LD1]

Could be a deere 755 crawler loader too. Also built in the 1980's, and could probably be had with a backhoe attachment as well.

 

[TractorTech]

Dan, if it is a Ford 755B, it's a shame that it sat as it is a dirt digging machine. As for pulling the'main valve', I assume it is the relief on the loader valve. Also, boom is referring to loader lift/boom? And bucket, the loader bucket? What does the oil look like now? Was there any rust on the valve? Had the water possibly cycled through the system before it was parked?
The oil flow goes from pump to loader valve and main relief to backhoe.

Without a little more description, but better, a pressure reading, it is difficult to diagnose. It sounds like the pump is bad or there is still leakage on the relief.

 

[LD1]

Dan, if it is a Ford 755B, it's a shame that it sat as it is a dirt digging machine.

Agreed.

My 5500 is the predecessor to the 755 series.

Not sure how similar the hydraulics are, but the 755's got a much needed power boost at the engine with a turbo added.

Without a better description and understanding of terminology, I am gonna be of little help.

If "boom" is refering to the backhoe, its odd that only it and the outriggers work.

Cause on my 5500, thee are TWO 3-spool valves. The left one (as sitting in backhoe operating mode) controls the dipper, boom, and bucket, the right one controls the swing and two outriggers. So its odd that only one function from the left valve and only 2 from the right valve work

 

[8NAcres]

Dan, if it is a Ford 755B, it's a shame that it sat as it is a dirt digging machine. As for pulling the'main valve', I assume it is the relief on the loader valve. Also, boom is referring to loader lift/boom? And bucket, the loader bucket? What does the oil look like now? Was there any rust on the valve? Had the water possibly cycled through the system before it was parked?
The oil flow goes from pump to loader valve and main relief to backhoe.

Without a little more description, but better, a pressure reading, it is difficult to diagnose. It sounds like the pump is bad or there is still leakage on the relief.

Sorry for the poor description, I am translating and I am pretty sure he is not using the true mechanical terms. As far as the valve, he called it the "main" valve and said there was a smaller valve inside it he cleaned as well - not sure if that helps. He said it comes off the pump and runs to the loader control. There was NO rust at all in the valve - he said there was a screen in the valve and it was completely clean. The "boom" as he called it is referring to backhoe - and it works fine ONLY as long as the loader control is held in a working position. The loader arms do not move at all - the "bucket" that does not work is on the loader. The oil looks fine now, and clean. He is not 100% sure no water at all was in it when he parked it, but he does not think so and keeps his running equipment well maintenance as he relies on it for work, this just had old sun-checked hydraulic hoses and heavy to run on customers lots so it sat for quite some time. He does not have a pressure meter for a reading, but said the pump itself appears to be working fine.

Thanks for the help!

 

[LD1]

So...trying to get this straight....there are 8 hydraulic functions.

1. Loader lift.....don't work
2. Loader bucket curl...don't work
3. Backhoe boom....works only if loader lever is held
4. Backhoe dipper...????????
5. Backhoe bucket...?????
6. Backhoe swing...?????
7 and 8...outrigger....works normally

Is that correct. Can you fill in the blanks

 

[8NAcres]

LD1 - just got off the phone with my FIL. Loader arms will not move no matter what. Loader bucket will not move no matter what. Backhoe arm and bucket will not move UNLESS the loader control is held in any operational position (does not matter if it is arm up, down, bucket curl, etc.), then it will move up and down and curl the bucket. Outrigger and backhoe swing is the ONLY thing that works fine without doing anything out of the ordinary.

Thanks!