753 Auxiliary Hydraulics

jjquarterhorse · Nov 28, 2009

I'm a new Bobcat 753 user and just got a backhoe attachment which attaches to the front hydraulics of the Bobcat. Is there a "trick" to getting the hydraulics hooked up? The top one snaps on pretty easy, but I have pushed and banged on the bottom connection and can not get it to lock. It acts as it is under high pressure. Is there any way to release the hydraulic pressure before I hook up? I get it to within about 1/8" of the detent and that's as far as it goes. Thanks all ... Great Forum! Jim

nerker · Nov 28, 2009

Not sure if this works on 753, but try to move your right hand "stick" right and left with engine off. That should bleed pressure to aux. quick connects.

jjquarterhorse · Nov 28, 2009

nerker said:
Not sure if this works on 753, but try to move your right hand "stick" right and left with engine off. That should bleed pressure to aux. quick connects.

Nope ... didn't work on a 753. I guess I'll have to disconnect the fittings and hope that releives the pressure.

jerry · Nov 28, 2009

jjquarterhorse said:
Nope ... didn't work on a 753. I guess I'll have to disconnect the fittings and hope that releives the pressure.

On your machine aren't the aux hydraulics controlled by switches? If they are turn the key on and without the engine running and operate the switch on and off and it should relieve the pressure.

jjquarterhorse · Nov 28, 2009

jerry said:
On your machine aren't the aux hydraulics controlled by switches? If they are turn the key on and without the engine running and operate the switch on and off and it should relieve the pressure.

Yes, there's a toggle switch on the front of the right stick and a trigger switch on the back of the right stick. I don't know what the trigger switch does, but the aux hydraulics are controlled by the toggle. I'll give your suggestion a try first thing tomorrow. Thanks!

skidsteer.ca · Nov 29, 2009

jjquarterhorse said:
Yes, there's a toggle switch on the front of the right stick and a trigger switch on the back of the right stick. I don't know what the trigger switch does, but the aux hydraulics are controlled by the toggle. I'll give your suggestion a try first thing tomorrow. Thanks!

Worst case loosen a fitting. Moving the hoe controls may help to.
But depending on the year of your 753, some of the old ones (753 753c 753F from the 90's) you turn the key backwards past stop and hold a couple seconds) and the newer G series (triangle head lites) have a "auxiliary pressure relief" white button up on the dash that you you use to shut the engine off.
Ken

jjquarterhorse · Nov 29, 2009

skidsteer.ca said:
Worst case loosen a fitting. Moving the hoe controls may help to.
But depending on the year of your 753, some of the old ones (753 753c 753F from the 90's) you turn the key backwards past stop and hold a couple seconds) and the newer G series (triangle head lites) have a "auxiliary pressure relief" white button up on the dash that you you use to shut the engine off.
Ken

Apparently there is no pressure relief built into my model 753 (not sure which model it is). I tried all of the suggestions from everybody's posts, and nothing seems to work. I guess I'll go get out the wrenches! Thanks all for the help. Jim

jerry · Nov 29, 2009

jjquarterhorse said:
Apparently there is no pressure relief built into my model 753 (not sure which model it is). I tried all of the suggestions from everybody's posts, and nothing seems to work. I guess I'll go get out the wrenches! Thanks all for the help. Jim

There is a guy in Colorado that makes a tool for relieving pressure. It looks like a bent tuning fork to slip over the fitting and a threaded rod that you screw down into the fitting to depress the end. Simple looking thing shouldn't be too hard to make one. I have never had this problem with the pioneer type fitting though. I found this through the search here hope it helps. Posted by mrfixitpaul on 8/17/2009 9:51:58 AM Are you relieving the hydraulic pressure? On the 853 you relieve the pressure by holding the ignition key to the left as you shut off the engine, and hold the key there for a few seconds after the engine is stopped. This won't work after the engine is stopped, as it needs some pressure in the rest of the hyd system to make the aux. spool move to relieve that pressure. This should reduce pressure enough to couple up. Otherwise you may have to loosen the coupler with a wrench and bleed off ...

mrfixitpaul · Nov 29, 2009

jerry said:
There is a guy in Colorado that makes a tool for relieving pressure. It looks like a bent tuning fork to slip over the fitting and a threaded rod that you screw down into the fitting to depress the end. Simple looking thing shouldn't be too hard to make one. I have never had this problem with the pioneer type fitting though. I found this through the search here hope it helps. Posted by mrfixitpaul on 8/17/2009 9:51:58 AM Are you relieving the hydraulic pressure? On the 853 you relieve the pressure by holding the ignition key to the left as you shut off the engine, and hold the key there for a few seconds after the engine is stopped. This won't work after the engine is stopped, as it needs some pressure in the rest of the hyd system to make the aux. spool move to relieve that pressure. This should reduce pressure enough to couple up. Otherwise you may have to loosen the coupler with a wrench and bleed off ...

All the 753's prior to the G series have auxiliary pressure relief if you turn key to the left and hold there for a few seconds, but the engine needs to be running at idle when you turn key to left. If engine is already stopped it won't relieve any pressure. Some models will only relieve one of the couplers and some do both, not sure which ones though. On the right control for the aux. the thumd switch is for intermittent control, the trigger is for continuous flow, like for the backhoe. The switch in the dash for the aux has 2 lights on it. when only one light is lit only the thumb switch works, when both are on the trigger and thumb switches should work.

jjquarterhorse · Nov 29, 2009

jerry said:
There is a guy in Colorado that makes a tool for relieving pressure. It looks like a bent tuning fork to slip over the fitting and a threaded rod that you screw down into the fitting to depress the end. Simple looking thing shouldn't be too hard to make one. I have never had this problem with the pioneer type fitting though. I found this through the search here hope it helps. Posted by mrfixitpaul on 8/17/2009 9:51:58 AM Are you relieving the hydraulic pressure? On the 853 you relieve the pressure by holding the ignition key to the left as you shut off the engine, and hold the key there for a few seconds after the engine is stopped. This won't work after the engine is stopped, as it needs some pressure in the rest of the hyd system to make the aux. spool move to relieve that pressure. This should reduce pressure enough to couple up. Otherwise you may have to loosen the coupler with a wrench and bleed off ...

Jerry & Mr.FixitPaul, I didn't have the engine running when I turned the ignition switch to the left ... I'll go do that now. Thanks for the help, and Mr.Fixit, thanks for explaining the aux hydraulic switches and controls. It's a new machine for me and I haven't figured everything out yet (can you tell?) Is there a way to tell by looking at the 753 what series it is? The guy I bought it from said he thought it was manufactured in the mid 90s, but he wasn't sure. Thanks again, Jim

soutthpaw · Nov 30, 2009

jjquarterhorse said:
Jerry & Mr.FixitPaul, I didn't have the engine running when I turned the ignition switch to the left ... I'll go do that now. Thanks for the help, and Mr.Fixit, thanks for explaining the aux hydraulic switches and controls. It's a new machine for me and I haven't figured everything out yet (can you tell?) Is there a way to tell by looking at the 753 what series it is? The guy I bought it from said he thought it was manufactured in the mid 90s, but he wasn't sure. Thanks again, Jim

let us know the year of your machine. My 753 has the key where you turn it counter clockwise from off (like acc position on american cars) it will release all aux pressure and should snap easy... do you have round or flat face connectors.. if you have the round ones, check for torn O ring in the female connectors.. sounds like I have a twin... post up some pics heh!

soutthpaw · Nov 30, 2009

jjquarterhorse said:
Jerry & Mr.FixitPaul, I didn't have the engine running when I turned the ignition switch to the left ... I'll go do that now. Thanks for the help, and Mr.Fixit, thanks for explaining the aux hydraulic switches and controls. It's a new machine for me and I haven't figured everything out yet (can you tell?) Is there a way to tell by looking at the 753 what series it is? The guy I bought it from said he thought it was manufactured in the mid 90s, but he wasn't sure. Thanks again, Jim

If it was mid 90"s then its not a G series. which is good if you work on it yourself...
the engine won't run with key turned to the left... its not supposed to.. it just activates a relief valve in the high pressure side of the aux hydraulics. then to run the backhoe once connected you press the aux hyd button so both lights are lit then press the right trigger once to start the constant flow to the backhoe...... the left trigger and switch are for the rear stabilizers... i did a couple posts about the benefits of the rear stabilizers not to long ago. my machine was plumbed for them already so not sure what is involved in adding the hydraulics for them but they work real well

jjquarterhorse · Nov 30, 2009

soutthpaw said:
If it was mid 90"s then its not a G series. which is good if you work on it yourself...
the engine won't run with key turned to the left... its not supposed to.. it just activates a relief valve in the high pressure side of the aux hydraulics. then to run the backhoe once connected you press the aux hyd button so both lights are lit then press the right trigger once to start the constant flow to the backhoe...... the left trigger and switch are for the rear stabilizers... i did a couple posts about the benefits of the rear stabilizers not to long ago. my machine was plumbed for them already so not sure what is involved in adding the hydraulics for them but they work real well

Not sure what the year is. Or the series. I'll poke around the machine and see if I can find anything to identify it. In the mean time, I've tried all the above suggestions, but nothing seems to work. I talked with the local Bobcat shop this morning and he said the machines that have use the ignition key to release pressure are old enough that the mechanism probably dosen't work any more (as opposed to the ones that have a pressure release button). Sooooo, I guess I'll finally give up and get out the wrenches. By the way, my backhoe is not a full backhoe like yours .... basically a bucket on a boom with one hydraulic cylinder which is controlled by aux hydraulics. It isn't much, but does most of the jobs I need to do around the farm. I dug a 200' trench in hard clay last week and it cut through the clay without a lot of problems.

soutthpaw · Nov 30, 2009

jjquarterhorse said:
Not sure what the year is. Or the series. I'll poke around the machine and see if I can find anything to identify it. In the mean time, I've tried all the above suggestions, but nothing seems to work. I talked with the local Bobcat shop this morning and he said the machines that have use the ignition key to release pressure are old enough that the mechanism probably dosen't work any more (as opposed to the ones that have a pressure release button). Sooooo, I guess I'll finally give up and get out the wrenches. By the way, my backhoe is not a full backhoe like yours .... basically a bucket on a boom with one hydraulic cylinder which is controlled by aux hydraulics. It isn't much, but does most of the jobs I need to do around the farm. I dug a 200' trench in hard clay last week and it cut through the clay without a lot of problems.

one thing that may work is lay a rag over the male end of the connector assuming you have the round end not flat ones and give it a couple hits with a brass hammer... that should let the pressure out of the system. do it on the backhoe side and the machine side... the backhoe you have does have advantages for certain things. digging long trenches for one that are not too deep and the ground doesnt matter if it gets messed up by constant turning of the skid steer to empty the bucket... also you have limited depth and reach

jjquarterhorse · Nov 30, 2009

soutthpaw said:
one thing that may work is lay a rag over the male end of the connector assuming you have the round end not flat ones and give it a couple hits with a brass hammer... that should let the pressure out of the system. do it on the backhoe side and the machine side... the backhoe you have does have advantages for certain things. digging long trenches for one that are not too deep and the ground doesnt matter if it gets messed up by constant turning of the skid steer to empty the bucket... also you have limited depth and reach

Yeah, I've done that with hydraulics on my tractor. The Bobcat has flat end fittings, so I'll need to take a wrench to the fitting. So far I'm pretty happy with my little digger. I figure that the money I didn't spend on a 'real' backhoe will rent me one many times when I have big jobs to do.

skidsteer.ca · Nov 30, 2009

jjquarterhorse said:
Yeah, I've done that with hydraulics on my tractor. The Bobcat has flat end fittings, so I'll need to take a wrench to the fitting. So far I'm pretty happy with my little digger. I figure that the money I didn't spend on a 'real' backhoe will rent me one many times when I have big jobs to do.

You could install the coupler block from the new series of loaders (03 or 04 and up) that has a manual pressure release built in the coupler, but you would have to run a new case drain line up to the couplers also.
Ken

ferenc · Jul 1, 2023

jjquarterhorse said:
I'm a new Bobcat 753 user and just got a backhoe attachment which attaches to the front hydraulics of the Bobcat. Is there a "trick" to getting the hydraulics hooked up? The top one snaps on pretty easy, but I have pushed and banged on the bottom connection and can not get it to lock. It acts as it is under high pressure. Is there any way to release the hydraulic pressure before I hook up? I get it to within about 1/8" of the detent and that's as far as it goes. Thanks all ... Great Forum! Jim

If you do go the route of the wrenches and there's no way to relieve pressure. You might go to high pressure quick connect fittings on the bottom. Meaning 10,000 psi. Those things don't need a pressure relief, but are expensive

Cheerio · Jul 2, 2023

I bought a Irwin ratchet clamp specifically for the aux. hydraulics. If I followed the instructions to turn the key to the left to relieve pressure it would always blow a fuse and the machine wouldn't start. I have arthritic hands and the wrench makes attaching and detaching quick and simple.

TonyCT322 · Jul 3, 2023

I have a couple of attachments that I know I need to fight with to connect. I broke down and bought the Irwin modified clamp from Skidsteer something. Usually requires a 3rd hand the line up, but does the trick. Rarely is pressure on the machine side the issue. The grapple sits out in the sun. Heat causes the oil left in the lines to expand. Won't let you connect. I usually loosen the fittings on the attachment to relieve the pressure and then connect. Some days I just need to walk away for five minutes and come back to it.

753 Auxiliary Hydraulics

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