Velvet Drive transmission over pressure

[SeaDogAK]

I have a pair of Velvet Drive S7000 transmissions (Perkins engines). The starboard transmission seems to build up too much pressure, to the point that when I pull the dipstick to check the fluid, there is a dramatic release of pressure along with a gush of ATF.

You’re supposed to check the fluid when it’s hot, but I don’t dare because I don’t want to get doused with scalding hot ATF.

Even if it’s been shut down for hours but still a little bit warm, there’s enough pressure to gush ATF.

The dipstick has a rubber seal that takes some force to release, and no matter how hard I try to ease it out so that the pressure can seep out slowly, it still gushes fluid. My engine room is a mess, and I don’t enjoy my periodic ATF showers.

My first thought was the breather valve, but replacing that didn’t solve the problem.

The transmission works fine, but I’m afraid that too much pressure will blow out a seal.

Does anyone have any other idea what might be going on? Is there some kind of vent or filter inside that could be clogged?

 

[boomerang]

I would revisit your vent again. There must be an obstruction allowing pressure to build up.

 

[SeaDogAK]

The breather is a little spring loaded gizmo that mounts in a hole on top of the transmission. I installed a brand new one but I don’t know how to check for a blockage in whatever is inside that little hole.

 

[SeaDogAK]

I suppose I could try running it with the breather removed and see if that relieves the pressure.

 

[twistedtree]

And get a look down the hole where the breather attaches. It should be open to the interior of the gear case.

 

[Bmarler]

My breather isn’t spring loaded, it’s just a cap sitting over the breather fitting. There should be zero pressure build up in the case.