L 1200 Front End Loader Hydraulic Pump Case Cracked

[torch]

High temperature at the pump is to be expected. High temperature at the filter is surprising. Makes me very suspicious. If it was me, I'd temporarily remove the entire filter assembly and connect the return line direct to the tank as a test.

 

[Dave_eng]

OK Dave,
let me get this straight, take the pressure line from the pump off at the control valve and connect it to the filter inlet fitting, by passing the control valve completely, right?

yea, I can shut off the fuel to the motor, using the fuel shut of valve at the tank, then drain the fuel pump and then it will only turn over and not crank.

Yes that is what I envisioned.

However, on further reflection, first connect the pressure line to the return line after the filter as a test of the best scenario for your tractor with absolutely minimal resistance in the hydraulic circuit.

If the hydraulic system is developing pressure as it appears, then it is dangerous and can inject fluid into your eyes and skin. You should be wearing eye protection and gloves.

The following info is found in all Kubota manuals

Dave

 

[Russell King]

Can you crank the engine with the fuel shut off so it does not start before you are ready for the BIG test?
Dave

That may not be necessary. The tractor looks like it has a decompression knob on the dash, upper left hand and looks like a choke if it was a gas engine.

Pull and hold it out and it will spin but not start. The engine should spin fairly easily and fast. Just don’t let it go if you’re not ready for the engine to start. The knob can pull back in by itself.

 

[mllkn6]

Yes that is what I envisioned.

However, on further reflection, first connect the pressure line to the return line after the filter as a test of the best scenario for your tractor with absolutely minimal resistance in the hydraulic circuit.

If the hydraulic system is developing pressure as it appears, then it is dangerous and can inject fluid into your eyes and skin. You should be wearing eye protection and gloves.

The following info is found in all Kubota manuals

View attachment 47443

Dave

Dave and Torch,
I think you both came up with the same idea at the same time, Ok, I'll do the return line first, if it checks out ok, then connect to the inlet side of the filter and try it to see if he filter is the problem, correct.

I wear glasses anyway, and usually wear gloves though fingerless ones. Thanks for your concerns, I appreciate it. Thought the info isn't in all Kubota Manuals, not the 1977 ones anyway. Remember my tractor was made in Japan, the only safe warning we got was, "Aso, be careful." LOL.

Yes it has a decompression knob as it's diesel, not gas. I use it only before I start it to release the compression then release it and start it. I didn't know I could use it that way too. I was told when I bought the tractor if you used it when starting it the motor could jump timing, so I never tried to use it when cranking it. Learned something new today, great.

 

[PoTreeBoy]

Dave's on the right track. I don't want to confuse things, but when you were using the little pump, were you running through that filter or bypassing it?

 

[Russell King]

Yes it has a decompression knob as it's diesel, not gas. I use it only before I start it to release the compression then release it and start it. I didn't know I could use it that way too. I was told when I bought the tractor if you used it when starting it the motor could jump timing, so I never tried to use it when cranking it. Learned something new.

The starting process is heat glow plugs, pull knob, crank, push knob, tractor starts.
Just don’t use the decompression knob to kill tractor except in an emergency (may harm tractor).
You can also use the decompression knob if you have to bleed the injectors.

 

[mllkn6]

Dave's on the right track. I don't want to confuse things, but when you were using the little pump, were you running through that filter or bypassing it?

PoTreeBoy,
It was running through the filter as well, everything stayed the same except the connections to the pump was moved to the rear pump connections is all, so there was noting going to the front pump then.

 

[mllkn6]

The starting process is heat glow plugs, pull knob, crank, push knob, tractor starts.
Just don’t use the decompression knob to kill tractor except in an emergency (may harm tractor).
You can also use the decompression knob if you have to bleed the injectors.

Russell King,
I use the glow plug before starting, pull the knob and then push it in, then start the tractor was how I was told to do it back then. Now I know better and it also bleeds the injectors which I didn't know. Thanks, I appreciate the help.
My old manual leaves a lot to be desired to say the least.

 

[PoTreeBoy]

PoTreeBoy,
It was running through the filter as well, everything stayed the same except the connections to the pump was moved to the rear pump connections is all, so there was noting going to the front pump then.

Hmmm, ok. I'll just standby and see what happens when you do what Dave said.

 

[Russell King]

Russell King,
I use the glow plug before starting, pull the knob and then push it in, then start the tractor was how I was told to do it back then. Now I know better and it also bleeds the injectors which I didn't know. Thanks, I appreciate the help.
My old manual leaves a lot to be desired to say the least.

It just allows the engine to spin easily while bleeding the injectors, and keeps the starter a bit cooler since it is working less with no compression. Sorry if I made it sound like it was more magical than that!

 

[mllkn6]

It just allows the engine to spin easily while bleeding the injectors, and keeps the starter a bit cooler since it is working less with no compression. Sorry if I made it sound like it was more magical than that!

Russell King, No, I appreciate the help and learning something new, my manual doesn't tell a lot about anything. It says to use the glow plug and decompression knob in cold weather or if hard to start, wrapped up in one sentence is all it says about either. I like learning something new, Now I know I don't need to turn off the fuel coming out of the tank, drain the fuel pump and remove the fuel lines at the injectors just so I could turn it over without it cranking, thanks to y'all.

 

[mllkn6]

Dave-eng, torch, PoTreeBoy,
Well all I had to do was run one test, connecting the pressure line from the pump to the reservoir refill line coming off the filter.
First I stuck the pressure line into the reservoir refill line and clamped it down, but this made the refill line bow so the fluid wasn't going straight in, yet it held together for a trial run that lasted about 60 seconds before I stopped it.
Then I used a 90 connected to a 1/2" pipe section to connect the two lines together, I screwed the pressure line into the 90 then slipped the pipe into the reservoir fill line and clamped it down so this way the fluid had a straight run into the refill line. Again I started the tractor, both ways the results were the same.
The fluid flowed from the pressure line back into the reservoir with out any problems, but the motor would only rev up to 1200 RPMs. If it doesn't work this way without the filter in between them then it sure would not work if I had connected to the filter to go through.
Something is restricting the motor from operating above 750 or 1200 RPMs, what it is I have no idea but a few guesses.
1. The hydraulic lines are to small, the old lines were all 3/8", I took one from the cylinders, the pressure line and the fill line to the pump for the place who made them to match, which they did. Had no problems working with the old pump as I used them for about 2 to 3 weeks before it cracked. Maybe the pressure line is too small, creating higher pressure.
2. Maybe it's in the plumbing coming off the pump. What was on the pump before was the same 90 as shown in the video, the one that is now leaking, but it was pointing down at a 45 degree angle and connected to the pressure line which made a long sweep down under the front axle group about 4" and it took a beating down there from stuff rubbing against it. I wanted to change it be level with the pump hence the long sweep pipe I put on that you see in the video.
I have made a brush guard out of 1/2" cold roll steel bars to mount in front of the pipe that I planned to put on after I get everything working right, so nothing can hit the hose or pipe.
3. Something is wrong with the pump, to much pressure or something. You can go to Bailey International's website and look up SKU # 118027 which is the pump I have to see the specs.
4. Some how the shafts are not aligning up which is creating stress on the pump and motor. Check out the video as it shows them running in it, they seem to be marrying up good to me. But the Bailey engineer said they would need to be way out of line to cause the motor to bog down.
5. It could be a combination of all of the above, again me guessing.
I even looked at the linkage that works off the throttle to see if it was binding in any way, nope working good. Then there is the controls, I'm not 100% sure they not working perfectly but I need the tractor operating at full speed to check that out. I do know they are not causing the problem of low RPMs since we bypassed them today.
I felt sure by us bypassing the filter that would make the motor open up, but nope it didn't, made a little more power but not full throttle.
OK, guys, anything anyone can think of that we need to do, sing out, I'm all ears.

 

[torch]

Looking at the spec sheet for that pump, it shows an outlet port size of -10 and an inlet port size of -12. Google produced this chart of hose sizes that suggests your inlet hose should be 3/4" ID and your outlet hose should be 5/8" ID to match the ports. I think my PTO pump for the backhoe are similarly sized.

So, yeah, maybe the hoses are too small. I don't know enough to say for sure, maybe the manufacturer would have better advice on that?

BTW: I ran my backhoe for several hours today and both pump and filter temperatures barely rose. They were slightly warm to the touch, but certainly nowhere near as hot as you described.

The only other thing I can think of is what weight of oil are you using? Although the pump spec says it can handle a range of wide viscosity range of 6 to 200 cTs, I think thicker oil would take more HP to move.

 

[PoTreeBoy]

You weren't going through the filter, right? You may have too much pump but don't change it yet.
Random thoughts:
What fluid are you using? Someone on here recently had a problem and solved it with thinner fluid: https://www.orangetractortalks.com/forums/threads/need-a-hydraulic-guru.47116/post-410788. I don't think that would completely solve the problem, but it may be contributing.
Your new pump is rated 6.8 GPM at 2000 RPM. Your engine is rated at 2800 RPM which would give 9.5 GPM.
9.5 GPM @ 2500 PSI needs ~17 HP
Looking at a B26 TLB on tractordata.com, which has about the same engine as yours, has a 7 GPM front pump.
But just pumping fluid around shouldn't develop that much pressure drop. 3/8" hose is probably too small. Fittings may have smaller openings acting like an orifice.
Could you repeat your heat gun test with just hoses and fittings and see if there's any hot spots? The other guys probably have some ideas.

 

[Dave_eng]

Thanks for doing the test.

I am concerned about doing more tests like I suggested as there is no relief valve protecting the pump.

My next thought is to have you buy the largest diameter pump discharge hose you can get.

Buy it long enough to reach the fill cap of the reservoir. Only have your hose maker put a fitting on one end to so as to connect to the pump outlet.

The hose can be cut to the proper length and a fitting crimped on to fit the loader valve once the restriction location has been identified..

Run the engine with the fluid going directly into the reservoir. The engine should be able to rev up now.

Dave

 

[mllkn6]

torch and PoTreeBoy,
The inlet hose is 3/4" ID and 1-1/4" OD, lined with mesh and a spiral wire, but the outlet or pressure hose is 3/8" as per what was on it before. My opinion is this pump is at least 3 times better than the old pump, it has 2 cylinder about 1" long x 2" wide where the old pump had 2 wheels 2" wide X .5" deep with teeth on them.
I have taken the long sweep pipe off and plumbed the hose directly into the pump, trying anything, didn't work that way either. So you may be on to something Torch, I get a 3/4" hose made up tomorrow and try it.
I think the heat is coming from the pump not being able to move fluid like it is suppose to do, which is bogging down the motor.
PoTreeBoy,
No, I wasn't going through the filter, not yet, still by passing it. My engine may be rated at 2800 RPMs but it will turn 3300 max the rated HP is 25.
Oil and hydraulic fluid is like politics on any auto or tractor forum, people fight over less issues than that. I used Kubota UDT till my local dealer retired and closed the doors. After that I went to NAPAs Hydraulic fluid approved for Kubota's UDT. Been using it since the dealer went out and it always work good.
Thanks guys.

 

[PoTreeBoy]

3/4 on the suction and 5/8 on the discharge should be good. You have to be careful with the bore and short bends with pipe fittings.

 

[torch]

Discharge hose would be 5/8", per the internet spec I quoted.

 

[mllkn6]

Thanks for doing the test.

I am concerned about doing more tests like I suggested as there is no relief valve protecting the pump.

My next thought is to have you buy the largest diameter pump discharge hose you can get.

Buy it long enough to reach the fill cap of the reservoir. Only have your hose maker put a fitting on one end to so as to connect to the pump outlet.

The hose can be cut to the proper length and a fitting crimped on to fit the loader valve once the restriction location has been identified..

Run the engine with the fluid going directly into the reservoir. The engine should be able to rev up now.

Dave

Hi Dave,
torch looked up the hose size chart based on the outlet port size 10 which says the outlet hose should be a 5/8" ID hose not a 3/8" like I got and what was on it. Or would it be better to go with a 3/4" hose on the outlet the same size as coming in to the pump?
I think you, torch, PoTreeBoy and myself are on the same page with what we all think the problem is. I'll pick up one tomorrow to try it and see how that turns out.
The 90 degree fitting that screws into the outlet on the pump has gone bad, it has begun to leak where the 90 is, I can screw the hose directly into the pump and make a long sweep out of it going back to the reservoir, then I can support it with ties so it doesn't drape down under the front axle like it did before and drag on stuff, unless anyone thinks I need the 90 out of the pump, to me it's just another restriction point.
Thanks

 

[Dave_eng]

Hi Dave,
torch looked up the hose size chart based on the outlet port size 10 which says the outlet hose should be a 5/8" ID hose not a 3/8" like I got and what was on it. Or would it be better to go with a 3/4" hose on the outlet the same size as coming in to the pump?
I think you, torch, PoTreeBoy and myself are on the same page with what we all think the problem is. I'll pick up one tomorrow to try it and see how that turns out.
The 90 degree fitting that screws into the outlet on the pump has gone bad, it has begun to leak where the 90 is, I can screw the hose directly into the pump and make a long sweep out of it going back to the reservoir, then I can support it with ties so it doesn't drape down under the front axle like it did before and drag on stuff, unless anyone thinks I need the 90 out of the pump, to me it's just another restriction point.
Thanks

When I do pressure loss calculations on HVAC stuff, the fittings account for 50% of the total restriction.

Likely similar on the hydraulic side so fewer elbows the better.

Also, when using fittings make certain they are hydraulic fittings not plumbing ones.

Dave