Oil coming out of the left side front axle vent hole when the plug is removed.

[mcmxi]

I did a bit of preventative maintenance on the BX25 last week which included an oil and filter change, a new air filter and a new transmission filter. This morning I adjusted the chain tension on the BX5450 snow blower and greased the fittings. I also checked the front axle fluid which appeared to be at the proper level and very clean. But here's where it gets weird. I loosed the front left axle vent plug and as I removed it oil started to come out of the hole, like it was under pressure! I quickly put the plug back in and then removed the front right vent plug and nothing came out, in fact, I couldn't even see oil inside the housing although the surfaces were wet with oil inside.

I'm going to buy some 80W or 90W gear oil tomorrow, drain the front axle and see what's going on. I have about 275 hours on the BX so it's a bit premature to change the front axle oil but it's not an expensive job, and I've had it for 5 years so it seems like a good idea. Any ideas as to why oil is coming out of the vent hole?

 

[85Hokie]

I have seen people get fancy and drill a small hole and place a vent TUBE on the plugs!

More on the subject HERE

 

[je1279]

I recently saw a video where the oil level on the front axle of a BX went from over full to not even reading just by removing and reinstalling the vent plugs on both sides. One would think that if they were working properly, neither a negative or positive pressure could be created inside the front axle. The fluid lowering when the vents are removed could be attributed to air bubbles in the bottom of the drop boxes working their way out with the additional venting but I can't explain what would cause oil to come out of one side on a level surface.

 

[mcmxi]

I recently saw a video where the oil level on the front axle of a BX went from over full to not even reading just by removing and reinstalling the vent plugs on both sides. One would think that if they were working properly, neither a vaccum or pressure could be created inside the front axle.

That's the part that leaves me scratching my head. As I'm sure everyone is aware, there are three reservoirs that include the center tube which houses the differential, and two drop boxes that house the gear drives. There's communication between all three in the form of oil and air movement so how it's even possible to have oil come out of the top vent on the left drop box is absolutely bizarre. The oil is only going to "spurt" out of the vent hole if it's subjected to pressure but how is that pressure possible?

 

[85Hokie]

how is that pressure possible?

Heat - the oil gets warm or even "hot" and thus it expands ..... and creates pressure.....

 

[mcmxi]

Heat - the oil gets warm or even "hot" and thus it expands ..... and creates pressure.....

The BX manual lists the front axle capacity as being 5.0 quarts. A temperature change from 20F to 80F would theoretically increase the volume of oil to 5.2 quarts. It was 28F at my house yesterday when I checked the oil level and removed the vent plugs on the top of the drop boxes. The tractor lives in a barn without insulation or a heat source and I checked the oil a few minutes after starting the tractor. When I removed the "dip stick" plug I would have released any air pressure assuming that there was any to release. I'm not trying to be argumentative, just wondering how this is possible.

I'll pick up some 80W-90 gear oil today and drain the front axle. Hopefully oil comes out of the right side drop box.

 

[85Hokie]

The BX manual lists the front axle capacity as being 5.0 quarts. A temperature change from 20F to 80F would theoretically increase the volume of oil to 5.2 quarts. It was 28F at my house yesterday when I checked the oil level and removed the vent plugs on the top of the drop boxes. The tractor lives in a barn without insulation or a heat source and I checked the oil a few minutes after starting the tractor. When I removed the "dip stick" plug I would have released any air pressure assuming that there was any to release. I'm not trying to be argumentative, just wondering how this is possible.

I'll pick up some 80W-90 gear oil today and drain the front axle. Hopefully oil comes out of the right side drop box.

I am with you 100% - I would think in your neck of the woods..... It would create a vacuum!!!

I too am curious why it is not equalizing - and causing pressure in the cold!

when you change the fluid - I would NOT add the entire amount - add 3/4 of it - drive around - allow to settle and add more...... HOPEFULLY it will equalize and you can get to the correct reading.

 

[je1279]

I have seen people get fancy and drill a small hole and place a vent TUBE on the plugs!

More on the subject HERE

Interesting read. I thought they were designed as vents but it sounds like they only serve that purpose for initial assembly. Here's a video I just came across that suggests it may be vented elsewhere also (not sure of the model in question in this video).

 

[je1279]

I just looked up the front axle on my LX2610 out of curiosity and there is a dedicated breather behind the dipstick (150). However, I am not seeing anything similar on your BX25.

 

[OrangeKrush]

I recently saw a video where the oil level on the front axle of a BX went from over full to not even reading just by removing and reinstalling the vent plugs on both sides. One would think that if they were working properly, neither a negative or positive pressure could be created inside the front axle. The fluid lowering when the vents are removed could be attributed to air bubbles in the bottom of the drop boxes working thier way out with the additional venting but I can't explain what would cause oil to come out of one side on a level surface.

I seen this and I’m still confused as to how the fluid dropped by opening that vent when it shares the same space with the dipstick.

The video you posted gives us something to think about.. making sure ours, if vented as his was is not blocked. Thanks for posting!

 

[je1279]

I seen this and I’m still confused as to how the fluid dropped by opening that vent when it shares the same space with the dipstick.

The video you posted gives us something to think about.. making sure ours, if vented as his was is not blocked. Thanks for posting!

Glad to help. A bit of searching on Google indicates that front axle seals may be problematic on the BX's. If there is in fact no breather/vent, one has to wonder if the increased pressure within the front axle is resulting in the seal failures.

 

[OrangeKrush]

Glad to help. A bit of searching on Google indicates that front axle seals may be problematic on the BX's. If there is in fact no breather/vent, one has to wonder if the increased pressure within the front axle is resulting in the seal failures.

I’m not sure if it has any vents yet., haven’t looked into it really. I do know the filler plug/dipstick is an Oring fitment so I would think that would let some pressure release before forcing a seal leak.

I’m on a truck forum and the rear axle vent is prone to seizing closed from corrosion., taking out an axle seal. I pulled mine and put a barbed fitting in and ran a hose with a filter up to the rear tail lens.. just in case!

 

[mcmxi]

I may have caused some confusion here. The dip stick indicated that the oil level was fine but I was confused by oil coming out of the vent plug ... that didn't make sense to me.

I picked up 5 quarts of Mobil 1 75W-90 gear oil this afternoon. When I got home I parked the BX in the garage, removed the dip stick plug, removed the left drop box vent plug (no oil came out), then removed the drain plug and a lot of oil came out. I removed the right drop box vent plug followed by the drain plug and a good amount of oil came out from that drain hole too. Not as much as the left side but still enough to indicate that the gear drive had plenty of lubrication. The oil has a significant grey metallic "flake" to it.

I have the axle draining overnight and will fill it tomorrow. I'll see how much oil I get out and then try to add a similar amount. I wonder if I could pour some oil in through the vent holes to expedite the filling process. A quart to each side followed by three quarts to the axle tube?