Overfill AT
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From: Texas
Overfill AT
Besides the obvious reason of AT fluid all over the floor of your garage, is there any good reason not to overfill the AT?
It wouldn't appear to cause the same issues as overfilling the crankcase with oil.
It wouldn't appear to cause the same issues as overfilling the crankcase with oil.
Three Wheelin'
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From: Dubuque, Iowa.
You will over-pressure the supply line to the transmission cooler and a leak will most likely occur at the hardline-hose transition between the torque tube and passenger side frame rail. Or, that is at least what happened when I overfilled mine years ago.
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From: Double Oak, TX
John,
Get down from the tree house with the young ladies and get under your car and check the ATF level the way it should be checked.
Roger
Get down from the tree house with the young ladies and get under your car and check the ATF level the way it should be checked.
Roger
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Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
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928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
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From: Texas
Ben, Why would overfilling the reservoir increase the pressure in the system? It just seems that the pump will have a maximum pressure regardless of the volume of the reservoir. I'm not saying you are wrong or trying to start an argument of any sort. I just have always heard " Don't overfill" but fail to understand how it would be bad for the tranny.
What if you put a larger reservoir in place of the stock one? That shouldn't damage the tranny, which in effect, is what you'd be doing by overfilling.
I know it sounds silly, but I just want to know.
What if you put a larger reservoir in place of the stock one? That shouldn't damage the tranny, which in effect, is what you'd be doing by overfilling.
I know it sounds silly, but I just want to know.
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IMHO, the pressure of pumping oil through the 20+ feet of small diameter pipe/hose, combined with banjo fittings at the transmission is a contributing factor in flexplate creep. (Even at the stock fill level.)
My old '86's flexplate stopped creeping when I put in a rear cooler, and straight through fittings. I have yet to convert my new '86, and it's flexplate moves the regular 3-4mm after a short time.
Note that the four speed has a thermo-valve inside that delays shifting when the oil is cold, which is annoying if you install just an air/oil cooler, I found. This time I'm going to use a thermostat, along with a cooler with an integrated fan.
My old '86's flexplate stopped creeping when I put in a rear cooler, and straight through fittings. I have yet to convert my new '86, and it's flexplate moves the regular 3-4mm after a short time.
Note that the four speed has a thermo-valve inside that delays shifting when the oil is cold, which is annoying if you install just an air/oil cooler, I found. This time I'm going to use a thermostat, along with a cooler with an integrated fan.
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Mine is overfilled. It used to leak a lot after the car was shut off. Now it doesn't leak much, but when I get the ATF hot, it will come out of the cap, compromising the seal. The wind also picks it up and mists it onto my exhaust pipes causing this lovely caked on crust... 
My transmission service is coming up soon, so I'm going to synthetic and making sure the fluid level is correct so it will never happen again.
My transmission service is coming up soon, so I'm going to synthetic and making sure the fluid level is correct so it will never happen again.