Front Axle Holding "Pressure"

smweatherman · May 24, 2013

Hello all
I searched some, but couldn't find this addressed. MX4700. I decided to check the front axle fluid level and when I removed the check plug I heard of 'puff' of air (tractor had been sitting for over a day). Level was fine, but the pressure (or vacuum) concerned me a little. I checked two more times over the last couple of weeks and got the same result. It is so quick I can't honestly say whether it is pressure releasing or a bit of a vacuum equalizing.

Is there a vent on the axle? If so where and can I clean it? If no vent, is this normal for others? Is this something I need to address? I don't want to blow a seal with built up pressure when it gets hot. I would have thought there was a vent to prevent much pressure, but I haven't found it yet.

Thanks for your comments

Chilly807 · May 24, 2013

Interesting question.. I can't honestly say I've ever noticed a vent hole on the front axle of my L3400. If there were one, it'd have to be above any possible waterline, unless you used a "duckbill" type vent cover.

Sean

whistlepig · May 24, 2013

I think this small gold "L" shaped tube coming out of the boss on top of my axle is a vent tube.

repete · May 24, 2013

My L2550DT had no vent ability in the front axle. I took the fill plug out and drilled a small hole then tapped it for a 1/8" pipe thread (I had to go to the side of the dipstick). Into that I put a 1/8" MPT to 1/4" hose barb fitting. I then ran a 1/4" fuel line up into the engine compartment. I put a 1/4" inline fuel filter (one that flows both directions) in the end of the hose just to clean the air as it breathes. I tied a rag over the filter when I discovered mason bees had filled the hole in the open end of the fuel filter.

JOHNTHOMAS · May 25, 2013

Interesting. I checked the rear drive wheels axle yesterday and heard this same sound which I'd never noticed before on my Kubota F3080.

kuboman · May 25, 2013

The L's don't have a vent. I did similar to repete but I just used a 1/8 dif vent. Unless you plan on running your tractor into a lake there is no need to run the vent any higher than the fill plug. Running a constant pressure or vacuum in not particularly good for the oil seals.

repete · May 25, 2013

kuboman said:
The L's don't have a vent. I did similar to repete but I just used a 1/8 dif vent. Unless you plan on running your tractor into a lake there is no need to run the vent any higher than the fill plug. Running a constant pressure or vacuum in not particularly good for the oil seals.

I agree on the running the vent up beyond the axle like kuboman did. I do a lot of work in mud so I just wanted to avoid the possibility. Maybe a throw back from the days of 4 wheeling in the Pacific NW.

smweatherman · May 25, 2013

I think I would feel more comfortable with a vent as well and going through the fill plug is probably as simple as anything. The front axle is not something I check too often so it took almost two years to notice this. I would have thought a vent would have been a standard item. The rear axle/hydraulics does have a vent.

Thanks for the replies.