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transmission fluid level

OntarioMax said:
So there is no vent for the overflow of the fluid?
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Even with the vent, it is possible to cause aeration of the fluid when overfilled. This causes slipping under load which will quickly destroy a transmission.

We deal with this a lot in fleet maintenance. People can't be bothered to set the fluid level correctly. Or borrow a dipstick from the wrong transmission because one is missing. Or fabricated dipsticks or just about a thousand other reasons to not do it the right way.

Ford transmissions are bad about giving up the ghost when overfilled. Not sure about the Aisins but it is definitely possible.
 
Meatball said:
Even with the vent, it is possible to cause aeration of the fluid when overfilled. This causes slipping under load which will quickly destroy a transmission.

We deal with this a lot in fleet maintenance. People can't be bothered to set the fluid level correctly. Or borrow a dipstick from the wrong transmission because one is missing. Or fabricated dipsticks or just about a thousand other reasons to not do it the right way.

Ford transmissions are bad about giving up the ghost when overfilled. Not sure about the Aisins but it is definitely possible.
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Aisins are very reliable. Some going 200K and the very lucky ones going near 1M miles with proper maintenance.
Those are probably never over revved and have the fluid changed way before it's needed, which is overkill but it's better in the long run I was told.
 
1990Volvo740GLNonTurbo said:
Aisins are very reliable. Some going 200K and the very lucky ones going near 1M miles with proper maintenance.
Those are probably never over revved and have the fluid changed way before it's needed, which is overkill but it's better in the long run I was told.
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Okay, I appreciate your response but my original comment was to the behavior when overfilled. Some apparently handle it better than others based on design.

I've never overfilled an Aisin transmission. Underfilled my S60 by about 1/2 quart one time and it acted like it had failed.

All I'm saying is put the correct amount of fluid in it it's not worth assuming that the vent will eject any overages. Cavitation is a pump killer. Aeration causes pressure loss.

Caveat emptor
 
OVERDRIVE said:
Cold can kinda be all over the place but 1/2" higher than hot is still lower than I've seen with the correct fluid level. There's a notch on the dip stick an inch or so above the max hot line, it's usually around there if not higher after sitting overnight.
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Thanks for that information
Also, is the fluid susceptible to evaporation or boiling away to a small degree if the ambient temperature, or operating temperature, is high?
 
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Checking Level When Fluid Is Cold. there is also a way to reliably confirm proper fluid level when the engine is stone cold and not running....e.g., after you've let the car sit overnight. On the dipstick, above the plastic part that has the two temperature-specific scales, there is a little rectangular notch on the metal portion. Assuming the fluid level is correct, and the car is stone cold and you haven't started the engine yet, if you withdraw the dipstick and wipe it off and then reinsert it, then upon withdrawing it for this second time the fluid level should be on that notch. This does NOT work if you just withdraw the dipstick and look at it -- you MUST withdraw it, wipe it off, and then reinsert it before withdrawing again to read the level.
 
OntarioMax said:
Checking Level When Fluid Is Cold. there is also a way to reliably confirm proper fluid level when the engine is stone cold and not running....e.g., after you've let the car sit overnight. On the dipstick, above the plastic part that has the two temperature-specific scales, there is a little rectangular notch on the metal portion. Assuming the fluid level is correct, and the car is stone cold and you haven't started the engine yet, if you withdraw the dipstick and wipe it off and then reinsert it, then upon withdrawing it for this second time the fluid level should be on that notch. This does NOT work if you just withdraw the dipstick and look at it -- you MUST withdraw it, wipe it off, and then reinsert it before withdrawing again to read the level.
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Using the method you described, What is he difference between the notch and the Max indication?
 
1990Volvo740GLNonTurbo said:
Using the method you described, What is he difference between the notch and the Max indication?
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The plastic max indicator marks for when the trans is either cold running or when up to temp. The difference is that the notch is only for stone cold engine reference.
So if the oil level when stone cold is slightly below the notch. You would carefully add a small amount of atf at a time to get the level to the notch. Do not go over the notch as an overfilled trans will puke fluid making a huge mess.
 
dl242gt said:
he difference is that the notch is only for stone cold engine reference.
So if the oil level when stone cold is slightly below the notch. You would carefully add a small amount of atf at a time to get the level to the notch. Do not go over the notch as an overfilled trans will puke fluid making a huge mess.
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The level when stone cold was well below the Notch. It was on the M of the Max. What fraction of a quart is that?
 
1990Volvo740GLNonTurbo said:
The level when stone cold was well below the Notch.
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Whose "stone cold"?
In Vostok Antarctica, it's currently -38 F.
In Managua, Nicaragua, it's currently +91 F.
The readings at their "stone cold" temps will be different.

1990Volvo740GLNonTurbo said:
It was on the M of the Max. What fraction of a quart is that?
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How high is "up"?
How many grains of salt in "a pinch"?
How much boob in "a mouthful"?

It's really, really, really not that critical to get some exact number of drops of fluid in the trans.
Start car. Check fluid. Is it somewhere in the COLD "zone"?
Go for a drive. Check fluid. Is it somewhere in the HOT "zone"?
If yes to both, close the hood and go enjoy the rest of your day.
If it's low, add a bit until it's in "the zone".
Jeebus Crisco. Stop trying to overthink it.
 
1990Volvo740GLNonTurbo said:
Sorry about that.

Another question though. Can the transmission additives AT 205 reseal and Seafoam trans tune be used in the same fluid?
Are they mixable without issues?
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I wouldn't. One is for cleaning the varnish off certain parts in the tranny, the other is more for rejuvenating the seals..
The AT 205 has a polymer that the cleaning chemicals in the Seafoam might negate.
The other issue depends upon the age of your transmission, and it's internal condition. If your fluid is dark brown or black, then the Seafoam cleaner chemicals might remove the varnish but slippage might begin.
I see where you are going with this though. The Seafoam is reputable, but is half the price of the AT 205.
 
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