Pressure Buildup in Hydraulic reservoir L3130 GST

[nmiller68]

I have an older L3130 GST not sure the year but it has 1700 Hours on it. I purchased it used about a year ago and changed all the fluids and made a few repairs to the FEL cylinder seals and of course changed all fluids and filters. The tractor has been very solid from the time I started using it.

I normally check all the fluids before I start the tractor at the beginning of the day. Today I did not do that first thing but instead moved the tractor to attach my 3pt auger. After I stopped the tractor I pulled the stick to check Hydraulic fluid level and a release of pressure from the reservoir was observed. This pressure is not so strong as to blow the stick out of the tube but fairly loud.

This does not seem normal to me and I was trying to find a cause of this.

I can not answer if it was always this way as I usually do not run the tractor prior to the check. Maybe the pressure would blead off over night.

 

[chim]

Clogged vent? On another forum a poster had oil being pushed out of the axle seals on his Mahindra due to pressure buildup. Mud daubers deciding to seal off a vent tube. Cleaned the tube and it corrected the problem.

 

[TheOldHokie]

Clogged vent? On another forum a poster had oil being pushed out of the axle seals on his Mahindra due to pressure buildup. Mud daubers deciding to seal off a vent tube. Cleaned the tube and it corrected the problem.

This topic always makes me wonder and this is a serious question:

The volume of oil returning to the reservoir is balanced by oil pulled out by the pump. How does this result in a positive reservoir pressure?

Dan

 

[chim]

This topic always makes me wonder and this is a serious question:

The volume of oil returning to the reservoir is balanced by oil pulled out by the pump. How does this result in a positive reservoir pressure?

Dan

My guess is it has much more to do with air than oil. There's a lot of air in the various cases, nooks and crannies. Maybe half the volume? As the air warms up it expands. When it cools it shrinks. It has all night (or a week or a month) between uses to slowly draw in replacement air in through tiny spaces, but much less time to expel the increased volume when it is heated.

 

[TheOldHokie]

My guess is that there's a lot of air in the various cases, nooks and crannies. Maybe half the volume? As the air warms up it expands. When it cools it shrinks. It has all night (or a week or a month) between uses to slowly draw in replacement air in through tiny spaces, but much less time to expel the increased volume when it is heated.

There is no doubt both atmospheric gases and hydraulic oils expand as they warm up. How much pressure can that create? Ideal Gas Law says not much. How pressure tight is a typical transmission/axle case?

Not trying to be argumentative just looking for some plausible answers.

Dan

 

[lugbolt]

There is no doubt both atmospheric gases and hydraulic oils expand as they warm up. How much pressure can that create? Ideal Gas Law says not much. How pressure tight is a typical transmission/axle case?

Not trying to be argumentative just looking for some plausible answers.

Dan

Science says it might only be, what, 20 psi (I don't know, just using it as an example). How much pressure can those pto, prop shaft, and axle seals take before they start to weep?

we have atmospheric air which expands with heat, and then we have hydraulic fluid that also expands with heat. They're both in an airtight "container". There is significant pressure buildup for sure if the vent can't, vent.

I know that a time or two I took a fill cap off of a warm tractor and the cap shot across the shop and the case vented a good bit of air. There's quite a bit of pressure-and air-that is trying to escape if the vent's plugged. If vent is open, it can slowly escape as it's warmed, but if it is plugged, it call comes out at once when the vent is "vented" (open the fill cap, etc)

 

[nmiller68]

Clogged vent? On another forum a poster had oil being pushed out of the axle seals on his Mahindra due to pressure buildup. Mud daubers deciding to seal off a vent tube. Cleaned the tube and it corrected the problem.

I had initially thought just that. Clogged vent. However I have found no vent or any reference to a vent location for the L3130.

 

[chim]

No scientific answers from me, but can relate a couple experiences.

The most impressive was several years ago when I left a half-full (or half empty for some) clear plastic water bottle on the black dash in my truck. Sun was bright with the truck facing South. Couple hours later sufficient pressure inside the plastic bottle pushed the concave bottom of the bottle out and made it convex.

My unvented plastic fuel cans stored in an unconditioned shed will either blow air out if it's warmer than when I placed them, or will have the sides sucked in if cooler.

 

[nmiller68]

I have an older L3130 GST not sure the year but it has 1700 Hours on it. I purchased it used about a year ago and changed all the fluids and made a few repairs to the FEL cylinder seals and of course changed all fluids and filters. The tractor has been very solid from the time I started using it.

I normally check all the fluids before I start the tractor at the beginning of the day. Today I did not do that first thing but instead moved the tractor to attach my 3pt auger. After I stopped the tractor I pulled the stick to check Hydraulic fluid level and a release of pressure from the reservoir was observed. This pressure is not so strong as to blow the stick out of the tube but fairly loud.

This does not seem normal to me and I was trying to find a cause of this.

I can not answer if it was always this way as I usually do not run the tractor prior to the check. Maybe the pressure would blead off over night.

Thanks everyone. I will keep an eye for any possible future issues. And if I do find a cause I will post an update.

 

[chim]

Does your filler cap have a rubber curlicue? If so that's a vent. (#80)

 

[nmiller68]

Does your filler cap have a rubber curlicue? If so that's a vent. (#80)

Well upon closer inspection it did not. It is supposed to be there but it was never there since I purchased this tractor. The cap was plugged. Once the part is obtained I will install and clear the cap.

Thank you for the help.