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Transmission leak at the track, breather?


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I recently took my getrag 245 equipped 2002 to a track day at Mid Ohio. Toward the end of the day I started smelling transmission oil. When I was able to inspect the car I confirmed it was transmission oil but I couldn't find any obvious location of the leak. Based on the location of the oil on the outside of the transmission, the oil appears to have come from high up on the front of the transmission where the breather and reverse switch are located. I have driven the car on the street for several years and done multiple autocross events and never had a transmission leak before. Has anyone had oil come out of the transmission breather when driving at high speeds? What do the racers do with their transmission breathers?

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I've seen fluid exit the breather on prolonged, high-speed runs in the race cars.


What I do (with transmission out of the car):

- remove the factory breather (it's a press fit -> pull it out)

- tap the hole (there's a pipe thread that's very close - put a small piece of paper in the hole to catch the filings)

- screw-in a brass 90° fitting with hose barb end

- install a breather hose and route up into the engine bay


Worth noting: I've never seen fluid climb up the hose - thus, it may not have to empty into a can.


Stating the obvious: Before any of this, confirm the reverse switch isn't loose or has fallen out. -KB

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My E-Production E30 pushed fluid out of the G265/262 close ratio box. Solution was as Ken suggested, tapped fitting to a catch can. Don't believe I ever found any fluid actually in the can so I suspect a length of hose some distance above the tapped fitting would give the fluid enough expansion room until it cooled down and returned to the transmission. Your race organizations rules may very well specify a catch can versus the hose approach. By comparison, my 2002 vintage race car with the G245/10 close ratio box doesn't seem to push fluid out of the transmission. Maybe I'm not pushing it hard enough. 



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I have had oil coming out of tranny to a can and then to engine bay. Reason was that my hose didn't run upwards all of its length. Putting it to a constant rise cured puking. At that occasion i used reverse switch position for breather. OE breather location is good. One can snap that plastic cap off but remaining pipe is rather short. Wiggle that out and push in longer pipe (w/ elbow ) for hose if tapping is not an option.

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I do what Ken does- tap for a 90.  Then the hose runs up into the engine bay, and joins another

catch can. 

I've never had that barf fluid.


I have had the stock breather get overwhelmed- I think something happens with lots of heat

and high cornering force.  It never snotted enough to matter, just made a mess.


I also put a breather extension on the diff- THAT little weasel will get far hotter that the transmission does.

As confirmed by telemetry.




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