What happens with too much trans fluid?

[bstone]

Drove from Boston, MA to New Haven, CT today. While on I-90W I noticed white smoke coming out from the back of my car. All the gauges were good and the car was driving fine, so I pulled over and looked. I was leaking a lot of transmission fluid (red, clear fluid coming from the trans).

 

After about 100 miles it seemed to stop. I checked the trans fluid level and it appeared high. I did add about 2qt last week as I had a few bolts loose on the trans oil pan and had leaked some out. I think I seriously overestimated how much came out at the time when the bolts were loose and overfilled the trans.

 

Is it possible that the extra fluid caused an increase in pressure which caused the trans fluid to come out? But when the volume returned to normal that stopped?

 

It's shifting fine. I'll check for leaks again.

Edited April 8, 2011 by bstone

[987687]

Are you checking when the engine is running?

[ShawnW]

Its a thermal thing. On the highway the fluid expanded and began to leak.

 

Its amazing how little is coming out when you spot a leak sometimes and an easy mistake. Run it thru all the gears, warm, and check it while its idling to see where the level is at. Drain some out if its overfilled. This unit likes a precise amount to be in it to work best and not leak, shift hard, etc.

[bstone]

The gaskets are less than a year old, put on by yours truly. Replaced them when I did the Duty C Solenoid last summer.

[forester2002s]

Too much AT Fluid can cause excessive 'frothing' inside the case.

The excess will then blow out of the air breather tube (on top of the AT case).

If the discharging froth gets onto the exhaust pipe/cat, that's when you'll see the plume of white smoke in your rear-view mirror.

It looks quite dramatic, but is unlikely to do any harm.

[Rooster2]

The ATF dip stick takes only a pint of ATF to fill from the "low" on the stick to "high" on the stick, so very easy to over fill. Best to drain to get to proper fill level.

[MilesFox]

i've had too much fluid in a 3at, enough that it was puking out of the fill tube

[bstone]

Too much AT Fluid can cause excessive 'frothing' inside the case.

The excess will then blow out of the air breather tube (on top of the AT case).

If the discharging froth gets onto the exhaust pipe/cat, that's when you'll see the plume of white smoke in your rear-view mirror.

It looks quite dramatic, but is unlikely to do any harm.

 

I think that's exactly what happened. You described it perfectly well.