Hydraulic reservoir building pressure?

[Isekirunner]

Hey everyone! In need of some ideas here for my Bolens 294. So recently I realized my hydraulic fluid was getting from my hyd reservoir into the trans/rear axle. I was losing fluid with no leaks so I check the transmission and it was way over full. Took the reservoir off today and checked the pan and no holes or cracks. Reinstalled the reservoir, refilled it, etc. After I started the tractor I took the fill cap off and ran the loader up and down. Everything looked good. I put the cap back on and ran the tph up and down a few times took the cap back off just to recheck the level and fluid was spewing out of the cap before I got it off. The cap is original and it isn't a breather cap. Is there some reason why the tank is building pressure? I'm thinking the tractor has been doing this and its been blowing fluid through the vent hose that goes from tank top to rear axle even though that was the first thing I checked before I took that heavy awkward tank off. If I leave the cap off it doesn't build pressure and foam out of the fill hole. There is a filter flange coming off the side of the reservoir. Could a dirty filter somehow be causing the fluid in the tank to pressurize because the pump isn't sucking enough fluid through? The filter flange doesn't have a plug where I believe usually there is for the bypass passage way like say on an oil filter flange. Any thoughts would be great, thanks

 

[Tx Jim]

Hyd reservoir I've seen have a breather for heat expansion.

 

[J_J]

Both heat and air will expand the fluid.

Are there any small air bubbles in the fluid after running the system .

You could have a suction leak and that will generate air bubbles.

Lots of cavitation will generate air bubbles.

You definitely need to let the fluid expand.

Are you sure the cap doesn't have a small hole that is stopped up.

 

[Isekirunner]

Thanks guys. JJ the cap is solid cast no hole. I thought maybe the reservoir could vent through the small hose coming off the top that goes down to the rear axle but I'm thinking the rear axle vents into the tank instead. I think I might just have took take some pics and investigate a little more.

 

[Isekirunner]

Well heres what I have found today. The fluid is foaming still with no loose connections. The fluid was right up to the top of the hole with the tractor running which is about an 1' higher than where it was shut off and I took the vent hose of the rear axle and the fluid dropped about an inch maybe a little less. I put black rtv on the sealing surfaces yesterday and that little breather hole for the rear axle had some squished into the hole so it was half the size it was supposed to be. I put a drill bit the same size as the hole in there a few times with a pair of pliers and opened it back up. Now the fluid is staying down from the hole. The dipstick for the reservoir is only about an 1 1/2" to 2" long so I think with the fluid on the mark for full its too much fluid for the loader when the bucket is curled up and the loader all the way down, so all cylinders are pretty much all the way in. Too me it seems as though it has been overfilled its entire life. The level where the fluid is now is sufficient for the loader at full height, it only goes down about an 1 1/2" in the reservoir when at full height and bucket dumped. With the tractor off the fluid is about an 1" lower than it was before when full. I will check it after the next time I use it and if the level doesn't change I'm gonna call it good.

 

[fxrs55]

I had a similar problem with my G154. The hydraulic fluid would bubble out of the
filler plug and then on to the ground. I realized that the oil foamed more
as it got colder outside. I finally figured out that the oil seals in the hydraulic
pump were old and hard and would suck in air as it got cold outside.
I rebuilt the pump and all is well now. I just used the tractor for
a couple hours today and it is still working good. It is cold here
in NJ and everything was working great. You more than likely
have a small hole or worn seal on the suction side of your pump.
check this link and start at post #170

 

[wdchyd]

I had a similar problem with my G154. The hydraulic fluid would bubble out of the
filler plug and then on to the ground. I realized that the oil foamed more
as it got colder outside. I finally figured out that the oil seals in the hydraulic
pump were old and hard and would suck in air as it got cold outside.
I rebuilt the pump and all is well now. I just used the tractor for
a couple hours today and it is still working good. It is cold here
in NJ and everything was working great. You more than likely
have a small hole or worn seal on the suction side of your pump.
check this link and start at post #170

X2^^^^^^What he said.......foamy oil = air entrainment from a suction leak (shaft seal, hose, tubing?)

 

[Isekirunner]

Thanks a lot guys! I'm gonna go over that thing again and double check all suction fittings. It could very well be the pump by the way its acting. It started this thing this summer where when I have an implement on that's heavy, sometimes I have to drop the tph a little to get the loader to work. If I don't drop the tph a little and try to raise or lower the loader it will barely move. Its strange how I have to move the tph a hair to relieve it so the loader will work at the right speed, I would like to figure this thing out. Then all that's left is splitting her in half for a new clutch. I love this tractor, its like a tank but I gotta get it workin right again. They don't make em like these anymore, now they have same hp and half the weight=useless to me.

 

[Leejohn]

Your feedback linkage isn't set right.

 

[Isekirunner]

Fxrs55 mine is like that when its cold. The loader wont even move for 15 minutes when the temp is 35 and under. Leejohn what exactly is that linkage? Is that inside the reservoir?