How to check your transmission fluid (NAG1)

[joseph]

This is a simple, effective way to check your tranny fluid yourself, you'll need these 3 things:
1) Temp/Fluid level chart, go to page 5 and print it to use it later: http://modsfaceoff.com/2005_dodge_ma...ck%209336'
2) Dipstick miller tool 9336 http://www.etoolcart.com/index.asp?P...OD&ProdID=7029
3) Digital high temp thermometer (you can use an IR themometer, that might work too, try it) http://www.etoolcart.com/index.asp?P...OD&ProdID=2556

Some info before we start: I got this started in this thread: Transmission dipstick available, take it for what it's worth (lots of naysayers), but you only need 3 things to check the fluid level, the chart to compare temp level to the fluid level, the dipstick marked in 10's (mm), from 10 to 80, and a way to accurately check the tranny fluid temp, which is what the starscan tool at the dealer is designed to do, but does the reading via the obd plug and gets the temp from that leaking plug (I believe), so I figured that the tranny fluid temp could be checked via the dipstick right after you pull it out of the tranny, hence the need for a good digital themometer that can read high temps.

This is what I've done:
After driving the car for 15-20 minutes, I pulled in my garage and put in the dipstick in to get it hot so that the dipstick would not be cooler than the tranny fluid when I check.You'll notice that the dipstick is way tool long, not to be used permanently, and will hit the bottom of the tranny pan, which is ok.

have your chart handy and the thermometer ready:

Next I put the thermometer on a hot surface to get it up to around 140 so that it would not take forever to go from ambient temp to fluid temp, you won't need to do this if you use an IR thermometer:

Once your themometer and the dipstick are hot after a few minutes and with the engine running, pull out the dipstick and immediately put the themometer probe at the twist of the dipstick where all the fluid will accumulate if the dipstick is facing down at a slight angle, repeat this a dozen times, mine hovered around 130 everytime, I couldn't take a picture because I only have 2 hands, one to hold the themometer and the other to hold the dipstick, but that's all there is to it.
When you take out the dipstick read the level right away, and compare it to the chart, mine was overfilled, it was at the black pastic thing, which is 90, when it should be around 50-55mm when the fluid temp is at 130 (see chart). I'll take care of it when I replace my leaking o-rings and I'll refill it with 1/2 qt. less than I'll take out and see where it stands.


Some of you know I serviced my tranny recently but the o-rings are leaking again, just a little bit, but this time I'll get my o-rings from Mercedes, because they are said to be of better quality Transmission servicing


P.S.: there is some concern that the temp on the dipstick is not the same as read by the starscan, so I'll go to the dealer and I'll have them check the level, which they will do with the starscan (after I change my o-rings again in 2 weeks or so), then I'll go home and check it manually and see if my readings are accurate in accordance to the official DCX chart, then we'll know if my method works or not. Etheir way, I'm glad I have the dipstick to check anyway, to see if at least it's within the marks.

[joseph]

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[faster]

I understand that the trans level is designated when the fluid temp is hot (measured level vs fluid temp), but using this dipstick method....couldn't you determine from that meas what the level should be when cold (~65-70F) after letting it cool? Then use that level meas in the future for checking. That would do away with the need for hot temp meas. Just a thought to simplify.

[faster]

Sorry for duplication-can't delete
I understand that the trans level is designated when the fluid temp is hot (measured level vs fluid temp), but using this dipstick method....couldn't you determine from that meas what the level should be when cold (~65-70F) after letting it cool? Then use that level meas in the future for checking. That would do away with the need for hot temp meas. Just a thought to simplify.

[joseph]

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[quarky42]

Thanks for verifying this Joseph. I had talked to fnkychkn about this method sometime mid year this year and he tested it for me. He found a big discrepancy between the measured temperature and the starscan reported temperature.

Good luck! It would be nice to have a way to check my own fluid finally.

[joseph]

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[DannyC]

So how much does the dealer usually charge to hook up the Starscan? I'd like to have everything checked on mine soon. I doubt they hooked it up before I bought it. It was used so there is no telling when the last time it was hooked up.

Anybody have a good list of things that should be checked?

[joseph]

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[Meister]

Joseph, I believe I've verified, to my satisfaction at least, that 70mm is right where the dealer would put your fluid level, given a car normally warmed up, in town.

You'll find that in your other thread on the the topic, here: Transmission servicing

So looks like you've hit another one out of the park.

70mm it is.

[joseph]

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[mikeyb]

I found another way around the dipstick issue. I used the dipstick out of my Cummins diesel. It's long enough to hit bottom and I used a metric ruler for the measuring.
Any dipstick that's at least 40" long should work.

MikeyB

[joseph]

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[moparman53]

Have you ever checked it cold, like somebody else asked?

[BrilliantBlackHemi]

should be fine too, as long as it's long enough to hit the bottom of the pan, and from there, you can just measure in mm, the tip of the DCX dipstick is the 0 mark.

Hemi31 and I found out the same thing when we cut the dipstick from a 94 Dodge Ram 5.9L Magnum Tranny to fit the LX.