AT Dipstick Reading Seems Odd - PeachParts Mercedes-Benz Forum

BrierS · #1 07-27-2004, 03:21 PM

In the process of changing my 300TD's auto trans fluid and filter, I wanted to add a can of Trans-X to run for the next couple hundred miles. Prior to today I have checked the trans fluid a couple of times in the 1K miles I have owned the car. Today, I had a shock. When I carefully examined the stick I noticed a normal range reading on one side but just hitting the stick on the other. I flipped the stick over and checked several times. Unless I miss my guess, this trans has been running low. Has anyone else noticed this with their auto trans and does anyone know why it reads this way?

95300YDT-A · #2 07-27-2004, 03:48 PM

BrierS,

You should better read your manual about how to check the level of your auto-trany. There is nothing odd about your level readings!

Danny

BrierS · #3 07-27-2004, 04:22 PM

Quote:

Originally posted by 95300YDT-A
BrierS,

You should better read your manual about how to check the level of your auto-trany. There is nothing odd about your level readings!

Danny

Unless you are reading a different manual than I am there is nothing in either my "Owner's Manual 300TD Turbo" or my Haynes Service and Repair Manual that addresses what I was attempting to ask. What I was trying to ask after illustrating what I was doing was, has anyone had similar dipstick readings when following the proper procedure that applies to this transmission as well as probably thousands of others? Repeated checking consistantly shows ATF well above the "high" mark while the other side of the dipstick is within the normal range. To add some type of benchmark, the high reading is about 38mm or 1.5' higher. As I also said, I have checked it previously a couple of times and can now see how someone could be mislead by viewing one side versus the other.

Danny, if you have something in print that my manuals lack regarding this I would certainly appreciate you sharing it with me.
Thanks

elusive 190E · #4 07-27-2004, 06:19 PM

Just out of curiousity;

Are you checking the a/t fluid with the engine idling...

And the gear selector in park..?

I have seen the condition you describe especially just after adding fluid to the tranny...

I call it "dip stick smear"... [the filler tube gets fluid residue smeared/splashed all the way up in it theory...]

Generaly all that is needed is for the residue to drip and drift back to the pan, to get more accurate readings...

Only trying to help, thanks.

BrierS · #5 07-27-2004, 06:33 PM

Elusive 190E,
Yes. The procedure has been the same I used for years and that I learned during the years of owning/operating my service station. That is why I at first felt stupid and then realized that possibly others have seen such a wild variation i.e. particular to this trans. I checked it a few times before adding any fluid since I expected I would need to MitiVac a quantity of fluid out prior to adding Trans-X. Level, warmed engine, running in park, stick all the way in, just not locked. It has been a few hours since I added ATF and the Trans-X so I'll check it again to make certain it was not residue yet as I wrote above, the first checks were made before. I can certainly state two things; the shifting is already smoother and the occassional flare has gone, second, I'm worried about having run it one or 7.7 quarts low (actually less than 1 since it appears there is about a 1/2 qt. between stick marks).

elusive 190E · #6 07-27-2004, 06:45 PM

If tranny operations return to normal operations...

Everthing should be "A-okay"...

Just keep on motor-o-vating with that smile inside that all is well...

If the fluid drops to a lower level in the next 90 days...

With no external leaks noticed... check out the modulator valve, it may be allowing tranny fluid to migrate to the intake manifold...

Happy motoring!

95300YDT-A · #7 07-28-2004, 01:48 AM

Hello BrierS,

Apart from my EPC ( where I can choose the language ) I have no manuals
in English. My owner's manual is in Dutch but the procedure to check the A/T level is offcoarse allways the same.
You do not only as stated before, check with engine idling and gear selector in park but it is also of the upmost importance to have the tranny oil on working temp. That's 80° Celsius. So prior to check you have to drive at least 10 miles playing from time to time with the selector. There is really a lot of oil
inthere to warm up and as long as the tranny is colder than 80°, level reading will allways be to much.
These trannies are very, very sensitif to the oil level. To much will cause damage. To less and it start to behave completely different. In the first place it will change gears with a "jerk".
But regularly maintenance and the oillevel right, these trannies are working beautifully and will continue to do so for really a lot, a lot of miles!
Have a nice day,

Danny

BrierS · #8 07-28-2004, 03:26 AM

Danny,
Thanks but been there. Done that. Everything you wrote is standard procedure. The missing item from what you wrote is back to my question . . . when you pull the dipstick and compare the fluid clinging to the two flat sides, have you ever noticed if it is higher on one side than the other? This was my observation after repeated attempts to check the level. Careful examination did show that on the side where the level appeared to be higher, there were actually small, non-coated areas. Seeing these made believe it was picking the fluid up either from the tube as fluid was draining back from the stick being withdrawn or something similar. So, I had several "false" readings when trying to check the fluid. Be it a result of my carelessness or lack of familiarity with the MB, I could have cost myself a transmission if I had not discovered this. If others have found the same with their vehicles I thought it might be worth mentioning so others wouldn't make the same mistake I did. Thanks for your opinion.

95300YDT-A · #9 07-28-2004, 05:20 AM

Hello again BrierS,

I see wat you mean now! Don't be worried, there is nothing wrong with you.
The same happens to me everytime I check the A/T level.
I need 3 or 4 "tries" before being shure about the level.
It's just the way it is...

Danny

pmckechnie · #10 07-28-2004, 07:51 AM

I have seen this many times. I always look at both sides of the stick and go by the lowest reading. It is caused by the stick rubbing on the side of the tube when you put the stick in or take it out, I don't know which.
Just use the lowest reading and all will be fine.

BrierS · #11 07-28-2004, 08:04 AM

Thanks all for the info, opinions & of course, encouragement. Checked again this morning after making a 15 mile trip and it is certainly within the normal operating range. Now I'll have to watch to see if the level drops. Mission accomplished.

BrierS · #12 07-30-2004, 08:03 AM

Still holding steady and the trans is shifting better than it ever has during the brief time I have owned it. I now have enough miles with the Trans-X in that I'll change fluid and filter Monday. What are the opinions about running a can of the Trans-X along with the Mobil 1 ATF over the longhaul?

TimFreeh · #13 07-30-2004, 09:16 AM

This issue has been a long standing pet peeve of mine. Reading the ATF level with a MB dipstick is about as accurate as reading tea leaves.

I'm not sure why this happens but its really annoying - I've never figured out how to get an accurate reading. Most of the time I end up taking reading 20-30 times and just average the results.

janko · #14 07-30-2004, 09:19 AM

if memory serves me, in some past thread someone suggested wiping the dip stick with denatured alcohol. thought was this would provide an accurate reading as a result of doing so.

wols0003 · #15 08-05-2004, 10:44 PM

I read in the Mercedes manual that you should run the engine in park for one to two minutes before checking the tranny fluid level. I assumed that driving the car before checking the level would produce a false reading. The transmission reaches 80c way before the engine reaches 80c.