JD350 crawler loader , backhoe low hyd press

jtrichard · Post by **jtrichard** » Tue Jan 19, 2016 11:07 am

IF it runs moves and steers for $2500 it should already be in your drive way as for what is wrong with the hydraulics that should not be that big of an issue in the over all scheme of things

pondhogvt · Post by **pondhogvt** » Wed Jan 20, 2016 8:32 pm

I ditto what everyone else has told you:: this may sound foolish but I think it is either something very simple or the pump...

check the simple things first, if it is not one of them , then it's the pump.
check to make sure it has plenty of oil,, check to make sure the valve on your right as you sit in the seat is fully seated,, maybe when they last used the backhoe attachment it did not get returned and the fluid is bypassing internally,,,

I would check for water in hydraulic tank,, where I live it's been freezing for quite awhile so water settles and freezes and could be obstructing the suction side of pump and or the suction line..

of course the owner won't let you separate that line to check, so that makes things difficult... if everything else checks out that is humanely possible start looking at the pump in front of radiator.. check to see if it is turning as someone else said ,,, heed Leonards, and JT"S advice on the connecting of lines as it will blow your pump apart if not done right,, but I have seen rare times that instead of the pump detonating it stripped splines instead'

if that checks out check to see if it is the right pump.. the 450 loader backhoe used the big pump,, even the steel suction line and pressure out line is bigger then a regular 450 dozer pump .. check his old pump,, are the fittings the same as new pump?? if he got a used dozer pump he would have to take the fittings off his old pump and switch them or change all the steel lines.. if he bought a new pump it would usually come with the threaded holes into pump but no fittings to connect the line. so his old pump would have no fittings if he bought a new pump...

does this make sense to you,, if he bought a used pump then his old pump would still have fittings on it... if it does are they the same size as the ones on the dozer?? could be a clue to right size pump, best of luck Mark.

speedbear · Post by **speedbear** » Wed Feb 17, 2016 3:00 am

I am having the same problem with the same machine. But, the low power in the hoe just started recently. The front loader works quite well. The hoe stalls out trying to dig fairly soft dirt. I was told there is an internal pressure relief valve that could be the culprit, but where is it located? I know there is an external relief valve, because I already popped it & blew oil everywhere.
If the filter in the oil tank was clogged, would it not affect the front end loader and the drive system too?

Willie B · Post by **Willie B** » Wed Feb 17, 2016 6:28 am

The 410 backhoe, (wheels) has a priority valve. It needs high pressure to open. It diverts oil to prioritize steering. It severely limits loader function.

Might the engineers have added some variant of this to the crawler?

Stan Disbrow · Post by **Stan Disbrow** » Wed Feb 17, 2016 7:03 am

Hi,

The drive is independent of the loader and hoe hydraulics. Having the loader work OK tells me the issue is to the back end. Perhaps you have a failure internal to a hose. I have seen where a piece inside pops loose and forms a flap which restricts oil flow.

Stan

shinnery · Post by **shinnery** » Wed Feb 17, 2016 3:49 pm

I think I would look real close at the main quick-connects. Connected right and no trash in them.
Bryce

speedbear · Post by **speedbear** » Wed Feb 17, 2016 10:50 pm

What I can't understand is, why doesn't the engine bog down, when the hoe stalls? Even with low oil flow, the pump should still force oil to the cylinders. It might take longer than normal, but it should still reach max working pressure. This is what makes me believe there is a pressure by-pass somewhere, not letting the proper amount of pressure to build up in the cylinders,

Stan Disbrow · Post by **Stan Disbrow** » Thu Feb 18, 2016 5:34 am

Hi,

Oh, yes. Good point. You are not seeing a load. Yes, that does sound like maybe a bypass spring suddenly snapped.

What you are getting are all the things that have ever gone wrong for the collective group.

I can tell you the flap failure inside a hose took me a long time to find....

Stan

speedbear · Post by **speedbear** » Mon Apr 25, 2016 12:07 pm

I'm still trying to find a pressure relief valve on my 450. The hoe works even worse now. I cannot find anything that even looks like a relief valve. Can the relief pop-off valve on the tank affect the hoe. I don't know where to even
look anymore! My 350 manual mentions a flow divider with a hoe on a 350.
Does a 450 have this?

NWJD fan · Post by **NWJD fan** » Wed Apr 27, 2016 12:51 am

Do you know what model of hoe you have. At one time there would have been a data plate somewhere on the boom. On my model 92 hoe the system relief is incorporated into one of valve segments that control the outriggers.

speedbear · Post by **speedbear** » Wed Apr 27, 2016 9:02 am

My hoe is a 92, as the 93 is a slider type. Is there any additional plumbing/hose associated with the relief valve? I assume there should be something to send the fluid back tot he tank.

jtrichard · Post by **jtrichard** » Wed Apr 27, 2016 9:46 am

NO hoses or piping to the relief valve it is built into the hoe valve on one end there will be a hex "PLUG" that will be the valve

NWJD fan · Post by **NWJD fan** » Wed Apr 27, 2016 2:11 pm

If you go to jdpc.deere.com (John Deere online parts catalogue) and search your model of backhoe it will give you a parts breakdown. The model 92 hoe is actually for JD 300 and 400 industrial tractors but it uses the same mounting arrangement the crawlers do. Model 9250, 9300 and 9550 (and probably others) are ones commonly used on crawlers

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