Did the ATF flush (dropped the pan, cleaned everything out, flushed via return line) this weekend on my 98 auto Maxima, and poured 12.15 quarts of Mobil 1 ATF in. Just read that the tranny only holds 10 quarts, went out to check and sure enough my tranny fluid was 1/4" above the top of the hot line (measured after the car had been driven 50 miles). I know some how I'm gonna need to get the extra fluid out either via siphon or dropping the return line.

My question is why is it bad to have overfilled the tranny and what effects can it have? Longterm effects? The car has been driven 250 miles with the overfilled ATF.

 

I Think this extra fluid can create higher pressure within the transmission enclosure. This extra pressure may push the gaskets apart and create a leak. As far as the actual mechanics of it, i dont know if the gears or other parts may be affected...

 

Overfilling causes the fluid to become aerated, not good!

 

u will feel no power

 

yeah its gona foam up and bubble or something, is that right ?

 

12.5 quarts of ATF is definitely too much, but 50 miles of driving just before checking the fluid level could very well have elevated the temps to the point where it is also causing a high reading. To get a more accurate reading, I recommend you drive the car normally for no more than 10 miles (just enough to bring the fluid to normal operating temp) and then recheck it. I think you will get a different result.

 

The way I flush is drain the pan and fill fresh ATF. Remove return line and run vehicle till no more ATF is push out thro the return line. Stop car, now all the fresh ATF from pan is inside the TC (pan is empty), fill pan again and button up. Check level a few times after driving to check the level.

 

I heard if you overfill in ATF the car will roll more in neutral (even if its automatic). Can anyone verify this? I wouldn't want to give wrong advice...

 

When I overfilled on my other car it started to smoke after a few hundred miles.

 

It is not good for the transmission and can break it. You can siphon it out of the dip stick tube if you have about a small hose about 5 ft long.

 

Yeah definately not a good idea, maybe if he can't get it out...just drain alittle from the cooling line that goes into the radiator...

might be even easier than siphoning...