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BMW Automatic Transmission Fluid Leak – Shifter Shaft Seal

October 28, 2010

Q
My 1999 328i E46 will leak out about a cup of trans oil when put into reverse. This usually happens if the car has sat for more than 5 days. I cannot for the life of me detect the source of this leak. Where does the dipstick tube insert into the trans? I also noticed that one time I accidentally bumped the shifter into neutral while driving and then re-engaging the a/t into drive caused a gear-shaped warning light to come on at the dash display. I feel the a/t stuck in 3rd gear. I pulled over and stopped the car for two minutes, restarted the car and the warning light went away.

A
In order to try to diagnose the fluid leak, we are going to have to locate the general source of the leak. Are you saying that the leak happens immediately when you go to Reverse gear? If so, we should put the car up on jack-stands and duplicate the conditions that cause the leak. A cup of fluid is quite a bit and we should be able to see where it is coming from.

With the above point made, note that your A5S-360R transmission does not have a dip-stick for checking the fluid. The fluid is checked via the fill plug on the side of the transmission. How have you been dealing with all of this loss of fluid?

I would not worry about the transmission warning (and the “limp mode”) from the inadvertent neutral shift, if it was cured by restarting the engine.

Julius Replies:
Q
Yes, the fluid was leaking from the shifter shaft, the seal completely gone. I deal with the loss of fluid by raising up the car on 4 jack-stands and filling the plughole until it runs out. Now when I drive and I try to pass, sometimes the gear light comes on and I “limp” back to the slow lane, pull off and turn off the car for 1-2 minutes. When I did the tranny change, I used castrol import atf. Now I’m second guessing. What about Valvoline Maxlife? can’t afford OEM $35/liter. Need to buy a new shifter seal too.

 

A
Ah, yes, on the older BMWs it is not uncommon for the shifter shaft seal to begin to leak.  This applies to both the automatic transmissions (shaft is above the fluid pad on the driver’s side) and the manual transmissions (shaft is on the rear of the transmission, above the output shaft).  You should be able to replace the shifter shaft seal without removing the transmission.  Just remove the lever arm (that the shifter cable connects to) from the shaft and use a small seal pick to pull the seal out.

Click HERE for transmission shift shaft seal for your A5S-360Z transmission

The specified fluid for your transmission is the ETL-7045E fluid.  We do offer this in 1-liter bottles.  We’re not sure if the current fluid is at fault in your intermittent transmission faults, but it certainly would not hurt to get the proper fluid into it.

Transmission Fluid (ID your BMW or MINI model to see the proper fluid):

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