L3250 - no hydraulic pressure after engine rebuild

[rbargeron]

Attached is a clearer drawing of the hydraulic block labeling its ports and selector valve. I'm also posting the other drawing again so toggling between them is easy.

When no loader is present, the hose on the block we're calling the bypass connects from the "out" to the "in". When a loader is mounted, the bypass hose is disconnected from the "out" port and instead connects to the short hose from the valve. The other two hoses connect to the "out" port and the "tank" port (forward end of the block). This should be the setup you have if your tractor isn't modified.

Hope I've described it right - pictures of my L3250 don't help - it has an additional valve and hoses so it's too crowded to see. Dick B

 

[100 td]

tried unscrewing the hydraulic oil filter while running and dry as a bone

Go back a bit here.
Hydraulic pump can not pump and work 3pt and steering if it has no oil to pump. Oil most likely goes from tank(transmission) to filter to pump. You need oil at the filter. The oil seal of the filter to the housing must be perfect otherwise the pump will suck air. Also check there is oil in the suction pipe leading to the filter. Ensure there are no loose clamps/hoses in the suction pipe.
Is the filter a throw away or a canister/housing with internal filter, if internal type also check for seal/oring on base of canister if it has one as well as the top seal.
Is the hydraulic pump being driven, you may be able to remove the outlet pipe and see the pump gears.

Hydraulic pump was in a box for 12+ months? Main hydraulic pipe from Xmission was taped off to prevent dirt from entering.

Any of that tape still in place or a mud dauber in the the pipe or in the inlet to the pump?

 

[J03bota]

Thank you guys I picked up some new hydraulic connectors so I can properly connect the short hydraulic bypass hose from the input port of the hydraulic box to the output port (no loader config). Thought all I needed was a sex converter Turns out all my hydraulic connectors are obsolete.
With the Hydraulic box Properly set to bypass mode (valve setting included) I can now FINALLY rule out improper hose configuration if the hydraulic pump still doesn't work.
-Will double check for air leaks throughout the hydraulic pump system. I have a brand new hydraulic oil filter with brand new Rubber seal attached. Will double clamp the vacuum hose side just in case.
Thank you very much.

 

[rbargeron]

If the loader and connections worked ok 16 months ago, I wouldn't change any genders or fittings until the pump is pumping -then try to connect the loader the way it was.

Also, even though the connectors on the early BF loaders are a different brand and style than the later ones on LA loaders (Parker 60 series) they should work fine connected right.

Another issue is the holes in the L3250's hydraulic block were British straight pipe threads, so new replacements may not mate up right.

 

[J03bota]

Please see images:
Got the new connectors installed for the hydraulic bypass configuration.
All my hydraulic connectors are obsolete? Too bad
I also double clamped the suction hose connection just in case it was leaking air.
** Still dead.
Tried opening the two send lines hoping that it might bleed out some air and kick start the pump but no such luck.

** Quit early. Too cold up here in New Hampshire. Supposed to be on vacation this week. My wife is already disgusted with me and my long, intimate relationship I have with my tractor.

Maybe tomorrow I will pull off the suction hose and see if the hydraulic pump is doing anything Its being driven mechanically hello. It must be pumping right?
I never took the pump apart. I only disconnected it from the engine and removed the pipes/hoses. Hydraulics worked perfect before the rebuild.
If there is no suction does that mean I need to rebuild the pump?
Thank you very much.

 

[rbargeron]

In your middle pic, the screw should be turned counter-clockwise to point toward C

The wording on the hydraulic block drawing is not real clear.
When it says "implement is not attached" it means there is no loader supplied with the tractor, and no bypass hose was supplied either, and the "out" and "in" ports have plugs in them. In that case the screw slot should be pointed toward "O" (internal valve open), allowing flow to go thru to the 3-point hitch.

When a loader is supplied with the tractor, it comes with all the fittings and hoses, In that case, the screw slot should point downward toward the "C" closing the internal valve so power goes out to the loader, and the loader's power-beyond can go to the 3-point hitch. When boom and bucket are detached the short hose can be connected between "out" and "in" as an external bypass.

Unfortunately none of this addresses why your pump isn't getting oil. I think I'd try rigging up a way to pour oil in from above the pump to fill the air spaces as much as possible before running it.

 

[J03bota]

Hi Dick, I agree do not want to add another variable here. I was planning on only purchasing a male to male coupler so I can properly connect the bypass hydraulic hose to the hbox output connector without changing any of the main connectors but needed to change out both female connectors because the male to male coupler did not fit the obsoleted connectors. Will be changing the connectors back when I put the loader back on. Those 2 new connectors cost me about $55 at the Kubota Dealership because I wanted to make sure the connectors fit the metric hose.
Thank you Dick.

 

[100 td]

Note: I'm assuming there is unrestricted oil available in the inlet pipe to the filter. I'm assuming the filter is fully sealed. I'm assuming the hydraulic pump is spinning.

I had a look at the parts layout for your pump, did you replace the oring between the pump and the filter bracket/manifold? If you did, I would unbolt and check to ensure it is the correct thickness oring, and it is sealing properly.

Then remove the banjo bolt on the PS outlet on the pump, and remove the main flange outlet pipe on the pump.
From the opposite side of the tractor start engine, when oil starts spraying EVERYWHERE, shut engine down. You may be able to just crank the engine with the stop lever applied and achieve the same result, and less clean-up.

 

[North Idaho Wolfman]

As stated, you don't need a bypass hose, the slot on the side of the block is the valve to change from loader connected to loader disconnected, that will take out the need to change any of the fittings and any variable of a bad fitting.

That style of pump cavitates very easily.
A bad / clogged filter or bad suction line or fitting will cause the pump to not create enough vacuum to prime the pump.

 

[J03bota]

I think I'd try rigging up a way to pour oil in from above the pump to fill the air spaces as much as possible before running it.

I agree will try this next.

A bad / clogged filter or bad suction line or fitting will cause the pump to not create enough vacuum to prime the pump.

I never threw the old hydraulic oil filter away.
Should compare the rubber gaskets to see if the previous filter gasket is thicker. They're both original Kubota filters.

100 td: Never took the filter assm apart. Tried removing the upper send pipes and got nothing. Something going on in the lower portion of the hydraulic pump
Thank you very much everyone!

 

[100 td]

. Something going on in the lower portion of the hydraulic pump

If the pump was working before, it will work again, without any repair, if you haven't done anything to it, as long as the inlet piping to it is sealed.

Note: I'm assuming there is unrestricted oil available in the inlet pipe to the filter. I'm assuming the filter is fully sealed. I'm assuming the hydraulic pump is spinning.

Recheck all of the above. Pull the hose clamps and the rubber pipe, check the rubber for damage, check for oil in the pipe. Shove the old filter back on if you think there is a chance the new one is not sealing, recheck you haven't got the new filter cross threaded. Whilst a remote chance that it's exacerbating the problem, remove your hydraulic filler cap as well in case your breathers are clogged, until you get it sorted.

 

[rbargeron]

At the risk of being declared a whack job here's something I've done for years fueling my tractors - and I think it could work to prime your hydraulic pump.

I keep diesel fuel in a clean 55 gallon barrel (new when I started doing this). I have a small air tube going into it that I can use to very slightly pressurize the barrel with compressed air. I put a 2 or 3 second squirt of air into it and the fuel hose delivers a nice gentle flow into the tractor tank. I give it another second of air now and then when the flow sounds like its slowing down. No hand cranking, no lifting and pouring, no drama. Just easily-filled fuel tanks.

As I though about your pump not getting prime, it hit me that a small air pressure surcharge on the transmission might do the trick. The important thing would be not to overdo it. About 1/2 or 1 psi should be plenty to lift the oil in the suction pipe up to the top of the pump - and away she'd go.

The lip seals on the transmission shafts would hold just fine - you might hear the breather hissing a little but by then you'd be done. If the dipstick lifted out you'd have put in a little too much air - but by then you'd be running.

Another side benefit would be if there are any leaks sucking air in, they'd show up right away - by sound and squirting oil.

As always, prompt cheerful refund if idea is bogus. Dick B

 

[J03bota]

Another side benefit would be if there are any leaks sucking air in, they'd show up right away - by sound and squirting oil.

Seems like a great debugging method at the very least
So here's the big question how do I charge the cavity. Maybe create new rubber filler cap and insert a bicycle pump needle valve into it?
And where is the Breather located?
Thank you

 

[D2Cat]

You might get an idea if you go to this link and about post #9 I posted some pictures of how I prime fuel in my Cat engine without battery or engine turning over.

See if you can adapt the idea. http://www.orangetractortalks.com/forums/showthread.php?t=31444

 

[J03bota]

Thank you D2CAT, great idea I might be able to wrap a tire tube around the filler tube in the back of the tractor with a pipe clamp. I think there is a big enough lip. If not then I'll try my idea of a rubber plug and a needle valve
If I loosen up one of the send pipes on the top of the hydraulic pump I can watch the air bleed out

 

[rbargeron]

I'd keep it simpler than that - wrap a plastic bag around an air hose and hold it against the oil filler neck in the back. Just hold it with your hand while the engine is idling - after maybe 3 to 5 seconds remove it (air should whoosh back out) - then try the 3 point. Might take a few tries to move the air pockets along in the lines near the pump. The hydraulics are open-center so once the air pockets go thru the pump it should keep going by itself.

Remember the importance of not over doing it. It should only need a small amount of air pressure - like blowing up a balloon. Dick B

 

[J03bota]

I'd keep it simpler than that - wrap a plastic bag around an air hose and hold it against the oil filler neck in the back. Just hold it with your hand while the engine is idling - after maybe 3 to 5 seconds remove it (air should whoosh back out) - then try the 3 point. Might take a few tries to move the air pockets along in the lines near the pump. The hydraulics are open-center so once the air pockets go thru the pump it should keep going by itself.

Remember the importance of not over doing it. It should only need a small amount of air pressure - like blowing up a balloon. Dick B

Hi Dick B, read your comment late.
I caught a break this morning and had a rubber plug left over from a previous project that fits perfectly inside the rear hydraulic tube. I then inserted/glued in a needle valve into the rubber plug. See Attached Image.
I have a hi-volume manual bicycle pump that I will use to inject air.
-- I hear you loud and clear and will Not Over-Charge The Chamber. I'll start off with 1/2 stroke.
Too cold today. Tomorrow is a better day - going to heat up to a whopping 20°.
Very excited about this back-fill idea. Thank you very much everyone!!!

 

[whitetiger]

You did put oil in the pump before you installed the pressure tubes didn't you? If not, take the tube back off of the top of your pump, put some oil in it so it came create a vacuum to suck oil up to and thru the filter.

 

[J03bota]

I finally got the hydraulic pump working. Applying air pressure through the xmission fill tube did not work. System would not hold pressure.
I then took off a send pipe, then both send pipes in an attempt to prime the hydraulic pump. While pipes were off I shined a flashlight into one of the pump send holes and saw the cylindrical pump mechanism. Tried rolling over the engine and noticed that the mechanism was not moving.
Took the pump off and realized that the gear on the fuel cam needed to be flipped so that it makes contact with the hydraulic pump gear. Please see attached images.
Pump worked almost instantly. Pump cavity and filter housing was still dead empty
Thank you everyone for all your help.

 

[100 td]

Well what can I say....
Glad you got it going!