new member with a tractor problem

[birdsnest]

I just bought a 1984 ford 1710 with a 757a backhoe attachment. After only about an hour of use the dipstick would drift down after lifting it. After learning a little about hydraulic principles I have come to the conclusion that the problem is probably not the cylinder. The cylinder has no external leaks and I can't believe the cylinder could let the dipstick drop without hydraulic fluid going somewhere to allow the ram to displace the fluid. I feel like the relief valve or the control valve are the problem but don't want to disassemble anything until I have some avenue to get replacement parts. The six station control bank is made by Kontak, an English company that has been acquired by Parker. I called a Parker distributor in Salt Lake City and although he was helpful, he couldn't find any repair kits for this control valve. Is there a source for repair parts, seals, o-rings etc. for this old machine. I have the old parts manual and operators/trouble shooting manual for the backhoe attachment which gives me all the disassembly procedures and parts numbers. Thought this forum would be a good place to start. By the way, there are no external leaks anywhere on the machine

 

[TimberHole]

A hydraulic expert I am not. I’m sure someone with more smarts will be along shortly. That said, what makes you think the fluid isn’t going around the o rings on the piston? The first thing I would do is repack the cylinder.

 

[birdsnest]

the way I understand it, both the upper and lower hydraulics fittings on the cylinder go to the control valve for that cylinder and both should be closed in neutral position. This causes a closed cylinder which would not allow the ram to move either direction due to the fact that the oil cannot be compressed or drawn out. I am no expert either but want to be feeling good about my first move towards repair. when the ram moves inside the cylinder, oil must be drawn into or out of the cylinder or it can't move. The stick will drop from full extension in about 5 to 10 seconds. About 20 minutes before it started dropping so radically it took about 10 to 20 minutes to drop so whatever changed did so quite quickly. All other functions are normal Thanks for the reply.. And I may be wrong about the cylinder.

 

[TimberHole]

Even if both sides of the cylinder are closed the dipstick drops if fluid moves around the o rings from one side of the piston to the other. Again, not an expert but am I wrong here?

 

[birdsnest]

I think we are both going to learn something pretty soon. No way I would call you wrong with my limited knowledge.

 

[MHarryE]

How fast is the drop? Control valves are not zero leak and have a specified leak rate by the supplier. It only increases with time. Rebuild when it gets objectionable. An example for me is my mini-excavator. If I leave the bucked a foot off the ground at night, it will be on the ground in the morning. Same for all the hydraulic functions under load when stopped. Internal cylinder leakage across the piston is not normally a leak down problem. For example if the fluid from the piston end leaks across to the rod end, where is the oil going to go? Example - moving the piston end May displace 4 cubic inches of oil but for that same displacement, the rod end chamber makes room for only 2 cubic inches. A cylinder internal leak is normally seen as loss of function. Direct oil into the piston end and it blows past the seal and out the rod port which at that time will be open.

 

[mikester]

How fast is the drop? Control valves are not zero leak and have a specified leak rate by the supplier. It only increases with time. Rebuild when it gets objectionable. An example for me is my mini-excavator. If I leave the bucked a foot off the ground at night, it will be on the ground in the morning. Same for all the hydraulic functions under load when stopped. Internal cylinder leakage across the piston is not normally a leak down problem. For example if the fluid from the piston end leaks across to the rod end, where is the oil going to go? Example - moving the piston end May displace 4 cubic inches of oil but for that same displacement, the rod end chamber makes room for only 2 cubic inches. A cylinder internal leak is normally seen as loss of function. Direct oil into the piston end and it blows past the seal and out the rod port which at that time will be open.

Bingo!

Surprised by hydraulic leak down on a 1984 machine? I was surprised when I was told by GM that 7L of oil consumption every 5000km was considered “acceptable” for a gas engine...

You will probably spend more money chasing that leak down than the machine is worth.

 

[birdsnest]

Does anyone know of a parts source for the 757a hydraulic controller?

 

[Industrial Toys]

Unfortunately, pretty much EVERYTHING is loose and leaks on many old machines. I have used the worst of them. Good for a pail of oil a day, but still cheap to get a job done.

 

[birdsnest]

I don't care if it uses TWO pails of oil a day, I just want it to work. Lets see, what is cheaper, add another quart of oil or rebuild the engine. We all know the answer to that question. If I was looking for a brand new machine I would have forked over $30,000 but instead I paid $2,000 and now need the backhoe to dig. I can afford to put some money into this machine and am looking for a little direction.

 

[Reb954]

https://www.tractorbynet.com/forums/hydraulics/214338-kontak-directional-control-valves.html

Maybe this thread will help. Maybe not.

 

[birdsnest]

Reb954, thanx. I was born a yankee but converted at a very young age. Sent pictures and gave description of what I need to this Brit company. Actually looks like they may have the parts for this oddball. Will know more soon since they are about 12 hours apart from me. I emailed them so now I wait. Appreciate the help. I thought it was spelled Windoming. HaHa. I'm a neighbor in Utah.

 

[fried1765]

Reb954, thanx. I was born a yankee but converted at a very young age. Sent pictures and gave description of what I need to this Brit company. Actually looks like they may have the parts for this oddball. Will know more soon since they are about 12 hours apart from me. I emailed them so now I wait. Appreciate the help. I thought it was spelled Windoming. HaHa. I'm a neighbor in Utah.

You might consider adding the "Utah" location to your profile.

 

[milligan36]

Try Worthington AG they are a big salvage outfit.

 

[birdsnest]

I wasn't comfortable with my assesment of why my dipper would keep dropping on it's own in 10 seconds. Iniitially thought it was a leakby on my hydraulic control but had to be sure so I swapped the hydraulics lines to a known good control and the same thing happened. It is not the control. It has to be the cylinder. The cylinder is the crowd cylinder and shows rebuild kit is not available. Anyone know of a source for the kit?

 

[Sportsman762]

Bridsnest the parts diagram for your back hoe is in the link below. Your local Case International or New Holland dealer can assist you with the parts. The part number for the rebuild kit for the crowd cylinder (dipper) is BMCAG00007, it has been superseded by BMCAG00083, the retail price on that is about $36. most seals for a hydraulic cylinder are standard, so any large hydraulic shop would probably have parts. However with the low cost (compared to most OEM cylinder seal kits) I would just get the OEM one.
Official New Holland Online Parts Store and Online Parts Catalog for New Holland and Ford Tractors.

Also in my opinion your comments on 8/6 were out of line, you failed to quantify the drift of the backhoe, slight drift is acceptable in most cases for most people. Please do not bite the hands helping you, Industrial Toys, and Mikster's comments were based off of their experiences, something you admitted you lack.

 

[searcyfarms]

Bridsnest the parts diagram for your back hoe is in the link below. Your local Case International or New Holland dealer can assist you with the parts. The part number for the rebuild kit for the crowd cylinder (dipper) is BMCAG00007, it has been superseded by BMCAG00083, the retail price on that is about $36. most seals for a hydraulic cylinder are standard, so any large hydraulic shop would probably have parts. However with the low cost (compared to most OEM cylinder seal kits) I would just get the OEM one.
Official New Holland Online Parts Store and Online Parts Catalog for New Holland and Ford Tractors.

Also in my opinion your comments on 8/6 were out of line, you failed to quantify the drift of the backhoe, slight drift is acceptable in most cases for most people. Please do not bite the hands helping you, Industrial Toys, and Mikster's comments were based off of their experiences, something you admitted you lack.

sounds like a PICNIC issue

 

[Rebeldad1]

I agree with TimberHole. A 2way ram can leak internally allowing the load to travel from one end to the other without a external leak. Think of it kind of like a french press.
You can put quick disconnect fittings on the ram and remove the hoses from the ram. The piston can still travel if the seals pass fluid.
That would be one way to check the ram.

 

[birdsnest]

have updated profile. thanx

 

[birdsnest]

In fact, on the 5th I stated the dipper dropped all the way down in 5 to 10 seconds and I really don't appreciate anyone telling me how to spend my money without knowing about this machine. I pulled the cylinder and a case dealer is resealing it for about $150 which makes my total investment so far at about $2,200. This machime is probably worth about $5000 so for someone to say I am probably going to spend more than the machine is worth is just wrong(at least to his point) I have already received priceless information from the members of this forum that has stopped me from chasing my tail. And that includes you Sportsman 762. I may have been a little out of line but will stand my ground when I feel like it. Certainly no personal attack was intended on Industrial toys or Mikester and the last thing I would do is bite the hand of those who are trying to be helpful. Thank you for for bringing this to my attention. BTW what is a picnic issue? Oh, I get it. HAHAHA. I did say I was new to this game but at least figured out to change the lines to isolate the control so not hopelessly stupid IMHO>