Hydraulic pressure

[Joshua Zahn]

The other day I bought a 3000 psi pressure gauge to test my system pressure. I also bought fittings per my interpretation of my brother's suggestion to hook into the one quick disconnects running from my loader control to junction block on the left hand side of the seat. I hooked it up prior to trying to start the tractor. I tried to start the tractor but it would not start. I looked at gauge and read approx 2550 psi as it was trying to start. I tried hooking to the other line and it read 0 psi and also the tractor would not start. I realize that this is no the Kubota specified way but at the time my buddy had my WSM. So my questions are a) is this pressure reading valid at all? and b)why would the tractor not start? It kind felt like the pressure guage on the supply line was causing the pump to dead head and not have the cajones to overcome the resistance. Is this the case? Or is the old girl playing tricks on me?
Thanks, Josh

 

[dusty-t]

Hi Joshua. Would the tractor start when you reconnected the quick connect. I don't know if you dead headed it or not but if you did, be very thank full that it did not start. Probably would have blown the pump. If the gauge showed 2550 then chances are that is what it is putting up. My thinking is that you should have a tee with the gauge that way it does not interfere with flow. Keep us posted. Dusty

 

[Joshua Zahn]

Whoops, I forgot to add that part. Yes, as soon as I hooked the quick connects back up she started fine. As soon as I get a chance I will get the right fittings and hook it up per WSM instructions. Patience is not my strong suit so I start looking for answers from you all before I get a chance to try it myself.

 

[traildust]

Whoops, I forgot to add that part. Yes, as soon as I hooked the quick connects back up she started fine. As soon as I get a chance I will get the right fittings and hook it up per WSM instructions. Patience is not my strong suit so I start looking for answers from you all before I get a chance to try it myself.

Hey Josh!
I'm actually glad you "don't have the patience" otherwise we wouldn't have known these kind of issues.

But like Dusty asked, was it T'd in? Sounds like it wasn't, at least I didn't catch it. T'd in should be fine as it is looped into the pressures system but in no way will it hinder the flow.
Sort of like an innocent by stander.

Keep us updated.

Scott

 

[Theekillerbee]

A pressure of 2550 psi is too high for your tractor. Like you surmised it dead headed your pump. Hopefully no damage was done. I don't recall the exact pressure of the little Kub systems, but I'd venture it is between 1500 and 1800 psi.

 

[Joshua Zahn]

Well no, the pressure gauge was not teed in to the FEL line as as soon as y'all mentioned it.....duh. Shoulda thought of that.

I tested the pressure as Vic described using the port covered by the hydraulic cylinder plug and following the guidelines in my WSM. I was going to try putting a tee in the FEL line and checking there but I bought the wrong tee at TSC. Needed a 1/2"NPT tee and bought a 1/2" JIC tee. I know NPT is National Pipe Thread but will have to look up JIC (and double check when I'm buying parts). Any how my pressure reading was topped out at 1000 psi.
I read about putting shim in to adjust the relief valve but.....according to my manual there is a different way to check discharge pressure by removing the delivery pipe from the pump and setting a control valve and gauge. However the reference picture sucks. It looks like they disconnected the pipe, set a tee with the gauge, followed by a valve to control flow and then a hose that is pushed in to the fill port of the transmission for the fluid to flo back in the system. Does this make sense? Is worth the trouble or is the the test I performed already pretty much the same thing?

Thanks you all, Josh

 

[Joshua Zahn]

Well I looked at a parts manual I had so that I could tell the dealer the number associated with the pressure relief shims that I needed. Except my parts page only showed a complete assembly whereas the WSM says you could shim the spring to fix it. So I called the dealer....and stumped him. After a few hours he called back and said yes, he saw the page I was referring to in the WSM and no, his parts list has no listing. So he asked the head mechanic who said in that situation he has used washers ground down to the correct thickness. It's kinda refreshing to actually hear that professional mechanics will admit to using old farmer tricks.

Josh

 

[traildust]

Well I looked at a parts manual I had so that I could tell the dealer the number associated with the pressure relief shims that I needed. Except my parts page only showed a complete assembly whereas the WSM says you could shim the spring to fix it. So I called the dealer....and stumped him. After a few hours he called back and said yes, he saw the page I was referring to in the WSM and no, his parts list has no listing. So he asked the head mechanic who said in that situation he has used washers ground down to the correct thickness. It's kinda refreshing to actually hear that professional mechanics will admit to using old farmer tricks.

Josh

Josh,
That is good news! glad to hear that the pieces are falling together for you. I hope it all works out and I can't wait for your post on the final fix.

Scott

 

[Joshua Zahn]

Well, I took the pressure relief valve body off to add a washer as a shim and found nut already in there that a PO had used to shim it. Added my washer anyway. Per the WSM a 1mm shim should add 380 psi. My washer was approximately 1mm and when I started the tractor and tested at the cylinder case cover port I had no change. This leads me to believe that the hydraulic pump is indeed bad unless y'all have any other ideas. Will have to wait a little while to get a new pump since they are pretty spendy.

 

[dusty-t]

Hi Joshua. So what pressure did your gauge show. Dusty

 

[Joshua Zahn]

Hi Joshua. So what pressure did your gauge show. Dusty

Dusty,
You'd think I would put all the pertinent info but it seems to slip my mind.
The pressure read 1000 psi as I actuated the 3pt hitch lever then dropped to 500psi about halfway through its travel.
Josh

 

[dusty-t]

Joshua, I was just reading back through your posts. and at one point you said that you're tph was strong but the loader was weak. On the hydraulic block where the loader hoses join to the tractor is there a selector for tph and loader.It kind of a shot in the dark but if that selector valve is off it will affect the loader. I don't even know if your tractor has this. My B7200 and B8200 had it. Like I said a shot in the dark. Dusty

 

[Joshua Zahn]

Dusty,
I'll check tomorrow for a selector. I can't recall one, but that would be perfect. Yes, the 3pt works great but the other day I couldn't even lift an old Chevy 6 cylinder with the loader.
Josh

 

[dusty-t]

This is a picture of the block on a B8200 the bolt sticking up at an angle with the little tit sticking out below it is the selector valve. Dusty

 

[Joshua Zahn]

My Kubota tech books says a .011 shim will increase the hydraulic operting system pressure by 200 lbs.

Releif pressure on the L275 is 2000 psi. The reference value for the hydraulic pump is 6.2 gpm, the allowable lower limit is 5.2 gpm, with 85% effeciency.

QWhen testing the system, you have to have the position control lever in the "up" position, so that you can hear the releif valve "buzzing" or whinning.

Engine must be at max rpm, or 2600 in the case of the L275.

Here's some info:

View attachment 1219

Thanks, Vic. That's what I did. I wasn't sure what 2600 rpm was so I tried once at half throttle and once wide open both with the same results. Great link! Any chance that y'all would post all your fancy manuals here?

 

[Joshua Zahn]

This is a picture of the block on a B8200 the bolt sticking up at an angle with the little tit sticking out below it is the selector valve. Dusty

Nah, I didn't get that lucky. I didn't see anything like that. Josh

 

[dusty-t]

Sorry to hear that, luck is a fickle mistress. Keep us posted. Dusty

 

[Joshua Zahn]

Well, I got my new hydraulic pump today. Messick's did not appear to have any in stock, neither did my local Kubota dealer so I purchased an aftermarket unit that is supposedly for my tractor. Hope to attempt the swap tomorrow after a building materials auction. Was looking in my WSM for text on the swap and found nothing. $100 for a book that gives very little info. (On the other hand the info it does give is pretty useful) Oh, well! Will keep y'all posted.

Josh

 

[traildust]

Good luck Josh!

Scott

 

[Joshua Zahn]

Well, it's been a few days, I've been lurking and not posting. The swap didn't go well. The pump that is supposed to replace my original doesn't have the same drive on the end of the drive gear. My original has splines and the aftermarket replacement has a rectangular tapered key like on a distributor shaft. My local Kubota dealer cannot tell me the difference in OEM parts number as there was a part number break depending on serial number. Of course, I have the earlier model and it is...wait for it.......discontinued and replaced by the other number. Luckily, the seller says he will take it back. The saga continues.....