713 backhoe pressure line blowing

levsmith · Dec 6, 2018

Hey all,
I am so close to having my 3400 backhoe/FEL going. This was a project that I bought not running so I've never seen the backhoe or FEL working. I got the filter changed and put new fluid in. I started the tractor and the main pressure line popped and spilled fluid everywhere. I put it back together and tightened the hose clamp and it blew the other end of the hose off, same situation. Long story short, it seems that it is building pressure but isn't able to flow freely. How would I see about figuring out the problem? I don't know if its the valve for the backhoe or if maybe the return line is clogged or a bypass or some sort? I assume the oil is continually flowing whether the valves are being used or not since its a crank driven pump. This is a 713 backhoe, and the plumbing goes from the pump, through the backhoe, then to the front end loader.

Thanks for any help! Hydraulics are foreign to me at this point, I don't have much experience with diagnosing them.

Sean in PA · Dec 6, 2018

A hose clamp will never be able to hold the pressure on that system. You need lines with proper hydraulic connectors on the ends. You can use hose clamps for the suction line going from the sump to the pump, but that's about all. Some folks use them on the final return line to the sump, but even that is not guaranteed to work, especially if there is a return filter downstream that might get clogged.

Andy Wickiser · Dec 6, 2018

Another thing, the 713 backhoe valve wasn't set up for "power
beyond". It was a simple open center valve. The original scheme
used a selector valve which sent high-side fluid to either the
backhoe or loader but not both at the same time.

levsmith · Dec 6, 2018

(quoted from post at 08:21:45 12/06/18) Another thing, the 713 backhoe valve wasn't set up for "power
beyond". It was a simple open center valve. The original scheme
used a selector valve which sent high-side fluid to either the
backhoe or loader but not both at the same time.

Thank you both for the replies! Andy, can you expand on this a little? Do you know where this selector valve is located? Is it something I have to manually switch? There is something that looks like a knob underneath the FEL valve but I have no idea what it does. Am I still right in assuming that the fluid goes through the backhoe valve? There is one large line coming from the crank driven pump to the backhoe, then another large line going from the backhoe to the FEL valve.

Andy Wickiser · Dec 6, 2018

First, the 713 is a prior generation backhoe to a 3400, the "native"
backhoe for a 3400 would be a 750 or 753.

Anyway the hydraulic plumbing kind of depends on what loader/backhoe
combination you have. Below are two circuit diagrams for the 713,
one for a 19-97 or 19-105 loader with selector valve (no power
beyond), and one for the industrial setup, 712 loader with power
beyond on the loader valve.

I'm not sure what loader you have, but if it has power beyond you
would send the pump output to the loader valve and the on to the
backhoe similar to the second diagram. If it has a selector valve,
the setup would be similar to the first diagram. The third picture
is the selector valve on my tractor (19-97 loader and 713 backhoe).

Since you are "mixing and matching" you'll have to figure out what's
best for your situation.

Another thing, if you blew the lines off under a no-load situation
you may have deadheaded the pump somehow. Be careful, such a
situation can blow up the pump.

<img src =https://i.postimg.cc/9FnB0SsD/713-With-Selector.jpg>

<img src =https://i.postimg.cc/rp6CC4Vc/713-With-Power-Beyond.jpg>

<img src =https://i.postimg.cc/m2YHfnBx/Loade-Diverter-Resized.jpg>

Andy Wickiser · Dec 6, 2018

Some additional information. I'm going to guess that you have a 730 loader, the most common for a 3400. Well, when the 730 was paired with a 750 backhoe the flow was different than in the 713 era. The pump output went to the backhoe valve first then, via power beyond on the backhoe valve, on to the loader. See diagram below. I think you have some engineering and plumbing to do.

<img src =https://i.postimg.cc/qRjd3yfM/730-750-Flow-Diagram.jpg>

levsmith · Dec 6, 2018

(quoted from post at 12:00:42 12/06/18) First, the 713 is a prior generation backhoe to a 3400, the "native"
backhoe for a 3400 would be a 750 or 753.

Anyway the hydraulic plumbing kind of depends on what loader/backhoe
combination you have. Below are two circuit diagrams for the 713,
one for a 19-97 or 19-105 loader with selector valve (no power
beyond), and one for the industrial setup, 712 loader with power
beyond on the loader valve.

I'm not sure what loader you have, but if it has power beyond you
would send the pump output to the loader valve and the on to the
backhoe similar to the second diagram. If it has a selector valve,
the setup would be similar to the first diagram. The third picture
is the selector valve on my tractor (19-97 loader and 713 backhoe).

Since you are "mixing and matching" you'll have to figure out what's
best for your situation.

Another thing, if you blew the lines off under a no-load situation
you may have deadheaded the pump somehow. Be careful, such a
situation can blow up the pump.
quote]

Thank you so much Andy! Can I ask what book those diagrams came out of? I bought a set of books for mine but misplaced them during my move. Those diagrams will at least allow me to see if it's plumbed correctly. Since it was a giant puzzle, I wouldn't make any bets

Mine does have a selector valve very similar to yours so it must not have power beyond. I know it is a 713 backhoe but I haven't been able to find a tag on the loader to be able to identify it. I've included a picture from one of my last posts if it means anything to you. Just looking at pictures online, it doesn't have the same bracing on top as a 19-97 or 19-105.

Andy Wickiser · Dec 6, 2018

The diagrams came from the Series 713 Ford Backhoes Service Manual.

I believe your loader is a 730. They did make a diverter valve kit
for the 730, see web page below, but I'm not sure what it was
intended for (as I said in a previous post with the 730/750 loader
backhoe combination of that period pump output went to the backhoe
valve first).
730 Loader parts diagrams

levsmith · Dec 6, 2018

(quoted from post at 14:01:09 12/06/18) The diagrams came from the Series 713 Ford Backhoes Service Manual.

I believe your loader is a 730. They did make a diverter valve kit
for the 730, see web page below, but I'm not sure what it was
intended for (as I said in a previous post with the 730/750 loader
backhoe combination of that period pump output went to the backhoe
valve first).
730 Loader parts diagrams

Thank you very much for the help so far, I'd be lost without it. I'll have to study these diagrams for a little while and see what I need to do. I'm sure I'll be back with more questions

levsmith · Jan 2, 2019

Okay I’m back, unfortunately... I had a hose made to replace the hose clamp/splice that the tractor came with. I got it installed, fired up the tractor and was able to run it without anything blowing, sort of. There were no leaks or anything but when I tried the FEL levers, nothing happened. Before I tried the backhoe levers, I decided to switch the output of the selector valve to see if that was the issue. That’s when things went south... the pressure built up and ended up blowing a hole in one of the old hoses, the one from the backhoe to the selector valve. Thats when I decided to really study the system and see if I can figure out what the issue is.

I noticed there is a plug on the selector valve. I am assuming when I pulled that valves lever, I switched it to the “plugged” outlet and the pressure had nowhere to go, other than the weakest hose. I don’t understand the point of the selector valve the way it is currently plumbed. I’ve attached a simple drawing of the way it is plumbed. I would appreciate any words to help me understand what I need to do to fix it. I obviously had pressure up to the selector valve, assuming it was going through that and into the FEL valve, why would the FEL not work? Air in the lines? I’ll be honest, I’m pretty mechanically inclined but hydraulics have never been my strong suit.

713 backhoe pressure line blowing

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