939 Checking the trans fluid

[mikey]

I have read the TM's and searched the forums, but can't find an answer to my question.

When checking the trans fluid for my M931A2, my truck has OE/HDO 10, I start the engine, let it warm up, put it in neutral with the parking brake on and I check the fluid level. I get the same result every time, picture #1. I am careful to slowly remove the dipstick.

If I immediately shut the engine off and check again, I get picture #2 every time. I'm talking about within 10 seconds of turning the engine off.

According to the TM, I should be adding some trans fluid based on picture #1 with the truck running in neutral. However, I want to be sure I don't overfill it. I'm cautious because the check with the engine running appears to have such little fluid on the dipstick. There is always a very slight amount just on the edge. What you see in picture #1 is what the dipstick shows every time I check it with the engine running. I want to be sure this is normal and correct before I add more fluid. It just seems strange to have such a small amount of oil on only one side of the dipstick.

Thank you!

Mikey

 

[Floridianson]

When im haveing trouble with the readings I wipe off the dip stick hit the stick with baby powder and knock off all excess take reading.

 

[Tow4]

The transmission needs to be at operating temperature or it will read low.

 

[mikey]

I always check the level when the truck has been running for at least 10 minutes, but I find no reference to "operating temperature". Yes it registers a temperature and yes it's below 180f when the pictures above were taken.

As per TM9-2320-272-23-5:

Withdraw dipstick slowly to prevent a false reading. If transmission oil temperature gauge reads
180°F (82°C) or below, level on dipstick should show between marks designated for normal run. If
transmission oil temperature is above 180°F (82°C) allow transmission oil to cool.

Mikey

 

[73m819]

A LOT easier way to check, first get the truck to op temp, make sure the level is correct, shut the truck down, let it sit till the next day, pull the stick, take a file and mark the COLD non running level. this way when you check the motor oil, you can check the trans also, the COLD level will always be the same, if low add till at mark, a lot easier dealing with a cold unit then a hot one.

 

[Ford Mechanic]

My 0.02 just worry about the running level of the oil. It's going to read high when it's not running, the pumps not pulling oil from the sump and not circulating it, passages drain and so on. All this plus the massive size of these units adds up to higher levels with engine off.
Pic 1 I would say needs more oil. Most of the time readings on the sides of the stick like that are from fluid that is coating the side of the pipe. Fluid won't drain that quickly off the side to get that reading any other way. Passenger vehicles typically read 1 to 1 1/2 quarts higher with the engine off just for comparison.

 

[98G]

A LOT easier way to check, first get the truck to op temp, make sure the level is correct, shut the truck down, let it sit till the next day, pull the stick, take a file and mark the COLD non running level. this way when you check the motor oil, you can check the trans also, the COLD level will always be the same, if low add till at mark, a lot easier dealing with a cold unit then a hot one.

I do this also, in all my vehicles. I've never been able to figure out why it isn't just standard procedure to read them cold, with a corresponding cold marking....

 

[VPed]

I do this also, in all my vehicles. I've never been able to figure out why it isn't just standard procedure to read them cold, with a corresponding cold marking....

I think it is because you cannot be certain about the volume that has drained out of the torque converters as it has been sitting. That can have a huge effect.

 

[charger53]

I do this also, in all my vehicles. I've never been able to figure out why it isn't just standard procedure to read them cold, with a corresponding cold marking....

I think it is because of the variables.... torque converter position can affect how much is drained back, how much fluid is left behind different valves and pumps? Just to many places for fluid to either drain from or be held within the trans. When it is running the pump is turning and everything inside is filled to capacity so the pan has a constant level?

 

[Ford Mechanic]

I think it is because of the variables.... torque converter position can affect how much is drained back, how much fluid is left behind different valves and pumps? Just to many places for fluid to either drain from or be held within the trans. When it is running the pump is turning and everything inside is filled to capacity so the pan has a constant level?

+1 for what he said. I've just been to busy as of late to add that.

Also you have to think about the fluid expansion due to temp. Fluid temps can vary drastically due to ambient temp, fluid at operating temps are typically predictably close regardless of ambient temp.

For example fluid level "cold" at 30*F will be lower than "cold" at 100*F but levels should be the same at both outside temps after a 30 min drive.