Kubota B26 blowing oil from vent

[woody]

I think it was overfilled and just blew out the excess. These are hard to get a reading on and if you check them cold they show down and but if you warm them up are ok.

it blew out so much that the oil would not touch the stick, but the new pump fixed that problem. the steering was where it all began and it turned out to be two separate problems.

 

[rScotty]

I think it was overfilled and just blew out the excess. These are hard to get a reading on and if you check them cold they show down and but if you warm them up are ok.

It certainly could be that simple... or not. What you are saying is why mechanics always check hydraulic fluid level when the fluid is at room temperature or colder. Hot oil expands and so does the sump volume, but they aren't equal. Hot hydraulic oil expands much more - and faster - than the more predictable change of the sump's volume.

That fluid expansion is the reason a lot of hydraulic fluid and power steering dipsticks have different fluid level marks for hot and for cold. To prevent overpressure problems, the vent is usually sized so that If the hydraulic oil gets filled to the hot mark when the fluid is cold, it will simply blow the excess out the vent until the level is right.

Hydraulic diagnosis is pretty straight forward, but trying to do it without temp., pressure, and flow gauges is sort of like dancing in a circle to make the weather change.
rScotty

 

[b26kubota]

It certainly could be that simple... or not. What you are saying is why mechanics always check hydraulic fluid level when the fluid is at room temperature or colder. Hot oil expands and so does the sump volume, but they aren't equal. Hot hydraulic oil expands much more - and faster - than the more predictable change of the sump's volume.

That fluid expansion is the reason a lot of hydraulic fluid and power steering dipsticks have different fluid level marks for hot and for cold. To prevent overpressure problems, the vent is usually sized so that If the hydraulic oil gets filled to the hot mark when the fluid is cold, it will simply blow the excess out the vent until the level is right.

Hydraulic diagnosis is pretty straight forward, but trying to do it without temp., pressure, and flow gauges is sort of like dancing in a circle to make the weather change.
rScotty

Thanks for your tip. Long story but the suction elbow at the hydraulic pump blew, but I could not see the hole or any issues with it. We checked the fluid hot an thought we overfilled it. It was blowing foamy fluid out the overflow. Between your comment and another thread on here, I was able to figure out that the elbow was sucking air. Saved me a trip to the dealer. From now on...I'll only check the fluid when cold.

 

[Smokeydog]

Have a friend who’s B26 had the same problem with the rubber elbow on the inlet pump side. The joining metal tubing was misaligned putting that rubber elbow in a strain that allowed it to in leak air causing foam and heat then fluid out the vent. Maybe poor factory assembly?? Replaced elbow and slightly and gently bent metal tube to better align to fix the problem.
On my B26 (newer, 2016) the tubing is better aligned but still check the tightness of the elbow clamps.
Air in hydraulic systems can cause considerable damage.