Overfull ATF

Messages
676
Location
TX south plains
I checked my ATF today and it was way full. Instead of being at the cold check mark (and it was definitely cold) toward the bottom of the dipstick, it was over the top of the readable area. I've heard this is muy bad for a transmission. I'm waiting on the last of the stuff I need to do a pan drop and filter change. Should I go ahead and drain some out? Will it affect how I do my pan-drop and filter change? Car is a 1994 Jag XJS 4.0L with ZF 4-speed. It's been this way since I got in in May and who knows how long before.
 
Messages
2,543
Location
Rochester, MI, US, World
You don't have to drain it any differently, but do drain it soon. My Focus was like this when I bought it, as it was 0.5 quarts overfilled. I drained out 3.5 quarts, and added 3 fresh quarts and I was exactly at the full line. And you are correct: running your AT with too much fluid is not good. If anything, you'd rather be a little low.
 
Messages
25,966
Location
Upstate NY
You get a more reliable check (in most cars) when the transmission is hot and you have gone through all the gears and the engine was left running to check it. I would not drain ATF based on a cold check. All I would use a cold check for is to see if there is any ATF at all.
 
Messages
2,995
Location
Cedarbrae, Ontario
Originally Posted By: cadfaeltex
Learning, I thought the cool mark on the dipstick was for a check when cold. I'll check it hot. So ATF condenses when hot?
It doesn't condense when hot, you check it hot while the engine is running to see the running level, when the fluid is being pumped throughout the system. When it is cold, it all runs to the fluid pan.
 
Messages
4,844
Location
Saskatchewan
Oil expands as it warms, so it will read higher on the dipstick when it's warmer. Since it has both cold and hot marks you can certainly check it cold or hot, as long as the engine is running when you do it. Temperature will affect the level, but it should always be within range and at a level that corresponds to fluid temperature.
 
Messages
543
Location
Illinois
Originally Posted By: rpn453
Oil expands as it warms, so it will read higher on the dipstick when it's warmer. Since it has both cold and hot marks you can certainly check it cold or hot, as long as the engine is running when you do it. Temperature will affect the level, but it should always be within range and at a level that corresponds to fluid temperature.
My experience reading trans oil level has been the exact opposite. My level reads high when it's cold and then it comes down to the normal level after the trans oil is hot.
 

cadfaeltex

Thread starter
Messages
676
Location
TX south plains
Ok, think I'm getting it. It's not the expansion or lack there of in the ATF, it how much of the system it's pumping through. I checked with the engine off so I got an inaccurate reading. Correct?
 
Top