Overfilling ATF fluid?

[CruzinA1A]

can any damage be caused by sligtly overfilling a transmission?

what would any symptoms be?

Thanks,

Mike

 

[FL_Rob]

How much might'slightly'be?

 

[CruzinA1A]

i think about half quart,,,
its been corrected now.....

 

[FL_Rob]

no worries ,even if you left it in there.

 

[CruzinA1A]

i dont know if its just my imagination but it seems that the shifts were a little jerky sometimes when it was a bit overfilled,,,,,

probably just in my head...

 

[MonumentOiler]

What vehicle ? Some transmissions are sensitive to overfilling.

The A343F in my 98 Toyota Land Cruiser had rough shifts when very hot and slightly over filled. I drained the fluid to the proper level using the right system (fluid at temp, level ground idling in park, ect...) and never a problem now.

It is most likely to have an effect when you get the trans temp up and the fluid is at maximum expansion.

If very overfilled there can be a fire danger when the hot fluid expands, escapes the case, and catches fire. Probably no danger of that with your situation.

The max line is there for a reason!

 

[Chris Meutsch]

I had overfilled the Civic a while back by probably 1/4 quart, and every time I stopped from long highway runs I could smell it. Eventually I got around to draining a bit out and it mostly went away.

 

[Michael_P]

Yeah, If overfilled it will spew out of the vent for a while leaving puddles and odors.

 

[SteveSRT8]

Not all trans have vents.

Many newer models have very carefully designed fluid levels for fuel economy. This is to prevent rapidly moving parts from touching fluids.

If the fluid is too high in these type of units you can get foaming and pressure variations, all kinds of trouble!

 

[ncguy]

I am sure there's no benefit to overfilling a tranny but as an old mechanic once said, "I'd rather have too much in one than too little."

 

[ScoobySTeveD]

Originally Posted By: CruzinA1A
can any damage be caused by sligtly overfilling a transmission? what would any symptoms be?


Our 2003 Acura TL 5 speed gets harsher shifts, especially to second, when trans oil is above te top marker. I don't think that it causes damage because it returned to normal operation afterwards.


My 1997 Subaru Legacy seems less inclined to downshift when I put my foot to the floor to induce a downshift if it is overfilled. Other than that, no damage observed.

 

[pavelow]

It's best to not overfill an automatic transmission. Some manufacturers are making that hard to do since some transmissions don't have a dipstick to accurately measure the fluid level.