Pressure in lower unit

[Jamz33]

I have an alpha 1 gen 1 lower unit and I have noticed when I took the top vent hole screw out it to check th fluid level one day it gushed oil out and you could hear air as well. From what I have found out the internet there is a vent hole that goes through the gimbal housing at 12oclock correct? Would this be plugged I assume or is there another explanation possibly? Thanks.

 

[achris]

That vent hole is not for the drive oil, it's to equalize pressure inside the bellows (or they's collapse or expand)....

The most likely explanation for such a pressure build up inside the drive is water ingestion... Drop the oil from the bottom hole and check it's condition...

Chris.........

 

[Jamz33]

I have checked the drive oil and it’s clean as a whistle. I’m just lost as to what it could be.

 

[achris]

The only other possible explanation is that the day you filled the drive it was cool and with high atmospheric pressure, and the day you opened it, it was warmer and with lower atmospheric pressure.

Chris......

 

[Jamz33]

So there is no reason that unit should build up pressure? One more question. The top screw says “vent hole”? Just curious as to why? Just a vent for when you fill it with drive oil I guess?

 

[achris]

... Just a vent for when you fill it with drive oil I guess?

This... ^^^

 

[Jamz33]

I am not sure I understand your last post?

 

[nola mike]

Yes, your assumption is correct

 

[Bondo]

Ayuh,..... Welcome Aboard,.... If ya don't vent the top of the oil cavity, ya can't pump in the oil from the bottom,....

 

[achris]

I am not sure I understand your last post?

You asked if the 'Vent' hole was for allowing air out of the drive as it was being filled. My reply was "yes"...

Chris.........