Do automatic gearboxes have breathers?

[bigfatnick]

Hi all, one i've never heard of here so i'll set the scene.

I currently reside in whistler, canada, where a large chunk of the winter olympics were, my mate has a $200 1994 ford econoline e350, its got a 5.8 litre v8, a 4 speed auto box, 2wd and as good ground clearance as a lot of 4x4's.

This mornings plan was to see how far he could get it up the mountain using the old logging roads that run round the side of the thing. We got maybe 3/4's of the of the way up and started to smell something, we stopped, shut the engine off and then i checked under and saw oil puking out and landing on the floor, then fizzing and splattering (think the green blood on aliens when it hits the floor). What i'm assuming has happened is that we boiled the gearbox oil, and what i saw was it boiling out over from the breather. The only thing is, i thought gearbox's were sealed, i didnt know they had breathers, can anyone confirm this?

The gearbox then pretty much stopped working, we rolled back down the hill until we got to a point we could turn around, the gearbox wouldnt engage reverse and in drive wouldn'd propel the car well. We happened to have spare fluid (the joys of oil leaks) and poured maybe half a litre back in and the gearbox seemed to work well again.

I'm not too fussed about possible damage, just concerned about where the oil was coming out? Any ideas?

[Simon says]

Yes auto trans have breathers,was the box over filled as trans fluid expands like a good un when it gets hot.

[bigfatnick]

cool, to be honest i thought it was under filled, but i think we just made it boil. The way it was frothing out onto the floor, it looked like a volcano! I guess if it was low on fluid anyway, it'd be easier to overheat the fluid and it'd be more likely to boil.

Thanks, nick