Airpressure in transmission - Normal?
 

Wanted to check transmission oil. When i removed the filler cap, i had a hissing noise for a short while like pressure equalizing. Is this normal?
Car was room temperature.

Oh, and i was missing almost a third of the transmission fluid, but the transmission is not greasy on the outside. Where'd it go?

A friend told me that normally a transmission has a breather valve designed to equalize pressure, and if that is clogged up this can happen.

Any ideas? I have searched the forum, and googled for hours now, but not a single post anywhere about this.
Can the valve be changed or cleaned, or??

Hope nothing is wrong, but if it is i need to have it fixed.

Regards
Niels Torlund

EDIT: It's a european manual transmission. They have 5 gears instead of the american 6.

I assume you have an auto...

https://www.rx8club.com/attachment.p...0&d=1213493541

By looking at that it looks like the overflow tube would be the breather so check for that. Good luck!

Thanks DeViLbOi, but it's a manual.
Got any other ideas?

/Niels

Unfortunately the lo-power manuals out there are not a lot since they were sold in a short time frame.
The transmission is pretty similar to the rx7 fd3s one, you may want to check that workshop manual :)

The American manual tranny doesn't have a filler...cap...it has a plug. And after filling my tranny with new fluid tonight via the gear shift...I don't know how it would get preassurized.

heat would cause it to pressurize. i would imagine.

Yes...but how are you going to build up enough pressure in the tranny and get under the car to open the fill plug before the pressure releases through the manual shifter? And who in their right mind is going to be messing with the top of the tranny when it is hot?

:dunno:

OK. Of course i ment a filler plug. Not a cap.
And yeah, i also think temperature changes is what causes the pressure, but i don't understand why i doesn't equalize better.

Anyway, i have changed the oil, so i don't run with a semidry tranny. There was a surpisingly large amount of metal powder on the magnetic drain plug. Scary...
I have ordered a new clutch, so i'm gonne be taking the tranny out of the car in a couple of weeks anyway. Then i can get a better look.
Hopefully there's no problem.

Thanks.