can't get air out

[scott1988]

I have a m5700 that I adapted a new holland tl270 loader to. Everything works fine except when I don't use tractor for a week. Hydraulics don't work at all until I remove supply line and let air out. I have no visible leaks. Once bled everything works great for a few days. Any ideas?

 

[wdchyd]

Suction leak on a suction hose, tube or shaft seal on the pump.......allowing the oil to drain back in the reservoir when not in use

Check all connections from the reservoir to the pump, if no obvious solution don't overlook shaft seal on pump

 

[scott1988]

Suction leak on a suction hose, tube or shaft seal on the pump.......allowing the oil to drain back in the reservoir when not in use

Check all connections from the reservoir to the pump, if no obvious solution don't overlook shaft seal on pump

Thanks I will take a look at those.

 

[Tx Jim]

Are you positive you have FEL valve correctly attached to tractor hyd's?

 

[scott1988]

I hooked it up the way a kubota tech told me to. It wouldn't work at all if it is hooked up wrong? Other than the functions being reversed.

 

[J_J]

You hyd system appears to be generating air, so check your suction line or replace and tighten clamps .

Look in your hyd tank after running and see if there are air bubbles in there.

 

[scott1988]

Can't visually see anything wrong with suction tube. Connections tight. Unless I'm looking at the wrong tube. It's about 1 inch diameter that goes from bottom of pump to side of transmission. There were lots of bubbles on dipstick. I will pull pumps shaft out to replace seals next I guess. Thanks for the replies.

 

[wdchyd]

Air entrainment is like drinking a thick shake with a small hole in the straw.....it makes bubbles in the oil

sometimes thick grease can be used to help locate the trouble area but it is not an exact science

 

[scott1988]

I have put new seals in with no change. Suction tube looks fine. I pressurized the tube while off to check for leaks and found nothing. What seemed strange was that when I took suction tube off the side of the transmission no fluid ran out. I had buckets under it thinking the fluid level would be above the tube. Dipstick reads full. If no fliud above suction tube, wouldnt it always drain back to tank creating air pocket? If I drive tractor while turning fully side to side it eventually bleeds the air out enough so the loader valve works but im afraid I will burn pump up since there is no fluid reaching it for approximately 2 minutes.
Thanks for replies. I guess the next step is to take it in and pay the big bucks...

 

[J_J]

Do you have a sump filter, and if so, check it out for sludge.

If a hyd component had an air leak, on the pressure side, it would also show a hyd leak.

If you take your pump hose going to the loader and place it in a bucket and start the tractor and run for a few seconds, you will verify if the pump is pumping.

If it does not pump fluid at start up, then I suggest your sump filter needs cleaning or replacement.

If you have air in the fluid, then you probably have a suction leak.

 

[scott1988]

That is how I was originally bleeding the system. I would remove hose, start tractor, fluid would start to cough out in about 1 minute then turn to full flow. I would then shut tractor off, re attatch hose and fill fluid to correct level. It would work fine for 2-3 days. I do also see air bubbles on dipstick. I have 2 hydraulic filters side by side near transmission, are these the filters you are refering to or is there an internal filter/screen? I parked tractor over white board in my garage to look for drips overnight and found 1 drop from steering cylinder. Barely visible.

 

[J_J]

What you describe indicates a clogged filter and a suction leak.

The screen on my Kubota is behind a hex bolt, and is cylindrical.

You should look at your manual and determine if the tractor has a sump screen and where it is.

Many tractor owners on TBN have found clogged screens on their tractors.

 

[scott1988]

No screen on it.

 

[J_J]

Your suction tube is made up with two tubes and 5 o-rings.

Are your filters fairly new or well used?

In order for the pump to function properly, the IN port has to be flooded.

If you do have an air leak, you could suck in air and cause aeration and priming problems.

 

[scott1988]

Yes I took the 2 sections of pipe and replaced all 5. It sure seems like the level of fluid in the trans should be higher than the suction tube and it was not so I don't know how it would ever stay primed. Suction tube comes out the side of trans and goes to pump as im sure you know.Crazy thing is dipstick on the back of tractor says full.

 

[scott1988]

Just bought tractor and dealer said engine oil and filters were changed but hydraulic filter don't look new. I picked up filters today so I will try that.

 

[scott1988]

Fluid should go from trans to suck tube to pump to hydraulic components to filters to tank I think.

 

[scott1988]

Tank being the trans

 

[Xfaxman]

I have put new seals in with no change.Suction tube looks fine. I pressurized the tube while off to check for leaks and found nothing. What seemed strange was that when I took suction tube off the side of the transmission no fluid ran out. I had buckets under it thinking the fluid level would be above the tube. Dipstick reads full. If no fliud above suction tube, wouldnt it always drain back to tank creating air pocket? If I drive tractor while turning fully side to side it eventually bleeds the air out enough so the loader valve works but im afraid I will burn pump up since there is no fluid reaching it for approximately 2 minutes.
Thanks for replies. I guess the next step is to take it in and pay the big bucks...

Yes I took the 2 sections of pipe and replaced all 5. It sure seems like the level of fluid in the trans should be higher than the suction tube and it was not so I don't know how it would ever stay primed. Suction tube comes out the side of trans and goes to pump as im sure you know.Crazy thing is dipstick on the back of tractor says full.

That is where your problem is. The oil level is too low or that is the return to tank tube, not suction tube.

Was the pump on the tractor or did you add it?

Pictures would help.

 

[scott1988]

Kubota diagram says its the suction tube so Im pretty sure its the correct one. I will change all filters and fill with new fluid this weekend and see what happens. I know it seems low fluid but dipstick reads full so I was afraid to over fill. Thanks