ATF fluid level-What's going on here? This doesn't make sense!

I have the same question on the S-10 forum but getting no answers. I have a 2001 S-10 with the 4.3L and the 4L60E automatic trans.Mileage is 46,000 miles.The only thing done to the transmission is I had an extra transmission cooler installed cause at the time I was going to do some towing. Ended up not doing any towing.
For some bizarre reason I went to check the ATF level and when cold it was about 1 inch "above" the hot line. When I would bring it up to normal operating temp the level was in between the marks. So at normal temp it was reading where it should. I left it sit for an hour and checked it again and the same result when cold. It read 1 inch above the hot line. Warmed it up and the reading was normal. Next time I let it sit for 6 hours and checked it and it was above normal again.
I started it up and waited less than a minute and the level came down to normal. I turned the engine off,waited less than a minute and it read 1 inch above normal again. This has me puzzled. Have worked on many cars through the years and have never come across this situation. Always before when the fluid was cold it would read low on the dipstick.
The only good thing about this is at normal operating temp the oil level is where it should be. The transmission itself shifts fine and the fluid color is very good. Any idea's whats going on? Many thanks!

My guess is that after it has been sitting for a while, some of the fluid drains out of the lines and internal parts into the sump, making it look like there is more fluid in the transmission. Since you are supposed to check it at operating temp, and your fluid level is fine, I would say you are good to go.

My guess is that after it has been sitting for a while, some of the fluid drains out of the lines and internal parts into the sump, making it look like there is more fluid in the transmission. Since you are supposed to check it at operating temp, and your fluid level is fine, I would say you are good to go.


I was thinking the same thing

One question. Are you sure your checking the fluid right. Flat ground? Engine running? Shifting through gears prior to checking level?

If your not doing that, then yes the fluid could be leaking down.

In my previous older hydramatics, there was a check valve in the torque converter to keep the oil in it while sitting overnight. When this valve leaked, the oil drains back into the pan.
I think it doesn't make a lot of difference as long as the oil is at the correct level when hot.
Possibly if the converter isn't pumped back full and you take off immediately when first started in the AM, it might be a bit sluggish?
Bob B

Your aftermarket transmission cooler is probably draining back into the sump as others have said. Sounds like gravity at play here.

Hope this helps. If you added a second cooler, rather than just a better one, then the increased fluid pressure itself would result in an increase in fluid in the pan when cold, as any stop valve in placed would have been engineered for the static fluid pressure based on a set amount of fluid from the manufacturer. Keeping in mind that "cold" fluids are more dense as well.

That is normal .
You are getting drain back from converter.
No problem.
Front wheel drives do it more than rear wheel.
Just.
Always check fluid when is is good and hot and park after shifting threw gears.
MT