Calibrate Transmission Dipstick 4r100

[Fitz98]

I want to calibrate my transmission dipstick for my 98 Expedition 4r100. I have 2 transmission tubes that are slightly different lengths, and 2 elbows that press into the transmission that are slightly different lengths. Depending on the combination, they vary in total length by 1/2". Does anyone know how far below the top of the pan the fluid level should be when full? The black mark here is the seat for the transmission pan. Here are some levels with the pan level (when the vehicle is level, the pan slopes down towards the rear) 9 quarts fills it to the rim

 

[samven]

If you can get a look at the service manual or talk to a dealer find out what the service fill is. That number is just what is in the pan when cold. I dont have your transmission but mine specs 5 qts service fill with filter change. You could look at a web site that makes aftermarket high cap pans to see if they give you any info on how much fluid you need then subtract the extra capacity from that and you have the factory amount.

 

[atikovi]

Kind of meaningless unless you accurately know how many quarts are left in the transmission and torque converter and cooler and lines...

 

[Fitz98]

A few days ago, I started the truck, got the truck warmed up, selected through the gears, shut down and drained the pan and the filter drained when I removed the pan as well. At this point, I would imagine a typical drain and fill quantity might be the correct approach. I thought perhaps there was a certain measured level below the top of the pan that was a target amount.

 

[Rand]

you check the atf level while its running?

 

[clinebarger]

Most GM rear wheel units is level with the pan rail HOT, I only know that because I paid attention to factory set-ups while servicing them. Without having a known good reference point....No one is going to be able to answer this question.

 

[oldhp]

Originally Posted by Rand

you check the atf level while its running?

I've never seen one not have to be running. Some are checked in Park.......Some in neutral.

 

[Linctex]

Originally Posted by Fitz98

4r100. I have 2 transmission tubes that are slightly different lengths, and 2 elbows that press into the transmission that are slightly different lengths. Depending on the combination, they vary in total length by 1/2".

Run the shortest dipstick with the longest tube/elbow. Done.

 

[Fitz98]

When I drained the pan originally, just by loosening bolts and letting overflow run out, I drained out about 4 quarts IIRC. Now filling back up, I have added 6 qts, and am getting an accurate reading of 6 qts based on water measurements I took referencing top of pan. That leaves room for 3 more before overfill. What I can't explain, is that I am right back to my original quantity I removed and replaced. So question would be, where would all that extra fluid come from that would overfill pan when it sits? I still should add more to get the running level to read properly on the dipstick, but I am hesitant. Anyone know how much should be in the pan by itself when refilling?

 

[clinebarger]

Originally Posted by Fitz98

So question would be, where would all that extra fluid come from that would overfill pan when it sits?

The Valve Body & Filter displaces fluid!

 

[Fitz98]

Thanks Clinebarger. It's amazing how sometimes the most obvious things can be overlooked. That would explain a lot, however... I put a mark on my dipstick where the top of the pan is. After refilling with the same amount removed from the system (I captured all I removed and filtered to replace. I just changed it not too long ago), The level when the engine is turned off is 1" below the pan at the front of the pan where the dipstick is, which is about 3/4" below the top of the pan at the rear of the vehicle, considering a slight rearward slope in the pan when the vehicle is sitting level. This is already taking into consideration the displacement, since it is installed. I don't know why the image below is posting upside down. In theory, if I was to let the vehicle sit and loosen the pan, I should have the same amount drain out the back of the pan as when I started this process (about 3-4 quarts). Is it possible as the vehicle sits, fluid drains back into the pan from somewhere else in the transmission, raising the level in the pan? Regardless, I am hoping I have resolved all this by repairing the dipstick tube seat seal, so even if the pan level raises, it won't leak out, but it was my understanding that the level should not be above the top of the pan when engine is off. End result is 6 quarts added to fill the TC and 6-1/2 qts added to the pan

 

[clinebarger]

You're assuming the fluid level was correct to begin with? Converter drain-back is normal & the rate it drains back increases as the unit wears. With the upper dipstick tube not seated....You were likely overfilling the unit assuming the dipstick itself was the correct one? Your original question "Does anyone know how far below the top of the pan the fluid level should be when full?" is EXACTLY what you need to know. If I knew that....I'd tell you!

 

[Linctex]

Originally Posted by Fitz98

Depending on the combination, they vary in total length by 1/2".

Just run it full, or a tiny bit over. No transmission will ever be harmed if filled 1/2" overfull by mistake.