Every year I drain and refill the transmission in my Infiniti and Chevy P/U. I drain the pan and pour it into a jug, so I can refill it with the same amount. Yesterday the P/U got refilled a little too much, as it's about 1/4 " above the x-hatched area on the dipstick, when hot. I know you're not suppossed to overfill it, but what does it do? How does this hurt the Xmssn? Doesn't it just back up the dipstick tube or what?
Transmission fluid level
- Thread starter malibu jimbo
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if you overfill the transmission by 1/4 a quart or more it could foam because there is too much oil in there and cause transmission failure try not to overfill it and if you do drain some out asap!
I do not think 1/4" overfill will cause any problems, I would not do a thing. The vehicle manufacturers must allow a "moron factor" when they design an engine or transmission. Your average person who adds oil or ATF is going to add it a QT at a time, not a little bit, check the level and maybe add more.
In addition in an engine you have the crankshaft and connecting rods not too far above the oil level and if they start bashing into the pan of oil you get foam, but that is simply not the case with a transmission.
In addition in an engine you have the crankshaft and connecting rods not too far above the oil level and if they start bashing into the pan of oil you get foam, but that is simply not the case with a transmission.
The fluid will expand, so if its a 1/4" in when cold, it could be a 3/8" or more at operating temp, depending on ambient temp of the fluid at installation and operating temps of the trans. You would have to know the thermal expansion of the fluid you used to know exactly how much it will expand at operating temps. That's why they always say, check at operating temp.
To remove some fluid just remove the top cooler line of the trans at the radiator cooler connection and run the engine a few seconds. If more come out than wanted, top off again but do not fill to the full mark when cold. Check it again after trans has warmed up to temp and then top off.
I would draw it down because an over filled trans is never good. First there is only so much capacity and if the fluid ever becomes over heated (like when towing) it will expand more and excess could be forced out the fill tube onto hot parts and cause a fire.
To remove some fluid just remove the top cooler line of the trans at the radiator cooler connection and run the engine a few seconds. If more come out than wanted, top off again but do not fill to the full mark when cold. Check it again after trans has warmed up to temp and then top off.
I would draw it down because an over filled trans is never good. First there is only so much capacity and if the fluid ever becomes over heated (like when towing) it will expand more and excess could be forced out the fill tube onto hot parts and cause a fire.
I don't think 1/4" over is a problem either, but if you're worried get a suction pump, for about $10 or so. It looks like a grease gun and is used for draining differentials, put a longer hose on it and suck out some fluid then top off to the correct level.
HTH,
Frank D
HTH,
Frank D
Good idea, Frank. Some transmissions are more sensitive to overfills than others. From what I know the Chevey p/u trans is not that sensitive to the overfill amount you are describing. (one of 2 possible transmissions). The concern is the same as in an engine, except the moving parts are not the crank and rod ends, but the spinning geartrain in the main body of the trans above the valve body. You don't want the fluid being whipped up into a froth by this spinning mass of gears and clutches while driving down the road. At the normal fluid level, the fluid is well-below the moving parts. It would take a considerable overfill to get to that point, IMO.
One of the trans(axles)that are sensitive to even a slight overfill is the 4T80E found in FWD 8 cyl Cadillac, etc.
One of the trans(axles)that are sensitive to even a slight overfill is the 4T80E found in FWD 8 cyl Cadillac, etc.
Checking the fluid level should be done once when cold and once when hot.
Engine should be running and in drive. Using the parking brake and in drive the dipstick level should be between L and H.
If the engine is off surely the marker will show much higher than H.
Engine should be running and in drive. Using the parking brake and in drive the dipstick level should be between L and H.
If the engine is off surely the marker will show much higher than H.
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I run 4 quarts in my 3 quart TL. I didn't want a gallon container of Amsoil sitting around so I dumped the whole thing in. Ran the engine for a while and checked for foam. None, so I drove it around town, checked again and no foam. So it's been run this way for 60,000 miles.
1/4 when hot is not a problem, I do it all the time
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