yodawill2000 wrote:Whoever posted awhile back about some magic hole that releases transmission fluid if it's overfilled please stand up !!!!
POPPYCOCK !!!
I consider you innocent until proven guilty....
Present your case.
Stand forward or forever stop the BS.
~~Going out to drain a bit~~
Installed a larger cooler because of the 3 digit heat i drive in and over compensated the fluid it would take for the larger cooler.
hasn't dropped a bit on the stick in two days of driving.
I'll take credit (or blame) for posting something similar to what you are saying... My transmission was also over-filled when I did my 1st drain and fill on the J. I put in close to the same amount that came out but hadn't checked the dipstick before I did that. 3 qts in to a 2 qt sump and my dipstick was well over the hot full mark
when cold 
This also means it had run over-filled for close to 10k miles and we see temps in Summer of 100+ routinely.
I have a long time friend who's a serious motor-head, more serious Datsun/Nissan/Infiniti motor-head and (amongst others) owns a '95 300zx TT (auto). He says the J and his TT share the same trans. He's also had his motor and trans out of the car a couple of times so has actually visually seen the vent, and told me "not to worry about being a little over filled", as it has this vent. It is a vent, not an over-filled transmission take-it-to-the-safe-range drain. Perhaps someone else posted something like that? I also ended up draining some out, btw -- but left it in the full "hot" range...
According to my friend, the vent is located towards the rear driver's side on top of the trans., I tried to look but couldn't see up there, so I cannot personally verify the vent is there. But if it's there, it is not to drain the over-fill condition, but to prevent over-pressuring the system and blowing seals, puking ATF, etc. I would bet there is some room between over-full on the dipstick and spewing trans fluid from the vent. Other vehicles have transmission vents too...
I am unclear as to what folks think will happen on a packed hydraulic system that automatic transmissions have that are over-filled. If it's unvented, you run a risk of blowing seals or puking fluid out the fill/dipstick tube and onto hot exhaust etc. (fire danger), or on a vented system puking out the vent, also potentialy onto hot exhaust. But unlike a wet sump motor that has a crankshaft that will whip over-filled oil into a foam, what do we think happens in an automatic? The sump shouldn't need an airspace other than for fluid expansion, right?
In any case, does anybody have a schematic of our trans that might show if the vent exists?? I'm all about getting edjumacated, that's why I'm here, and I try to contribute where I can as well...
There's a synthetic Dexron that is supposed to be compatable with plain Dexron III -- happened to pick up a bottle of universal fluid at Wallyworld (their brand) while I was helping my Dad w/ power steering fluid change out on his Toyota -- it smelled just as bad (as in the same) as the Ford Mercon V that I just put in my Expedition. It also said it met both Dexron III and Mercon V specs (Mercon V is only a synthetic). Hmmmm... At three and a half bucks a quart might be worth doing it...
) in general on an auto trans.
