Anybody else having problems measuring proper transmission fluid level? - PeachParts Mercedes-Benz Forum

MercFan · #1 08-23-2010, 05:02 PM

I know this is a stupid issue, but I can't seem to accurately measure the amount of fluid that's in the transmission and I know how important it is NOT to overfill it.

I've recently serviced my 300SDL with new filter/fluid. Filled it up with 4 quarts, started it and slowly added another 3 quarts - shifted to R-N-D-N-R-P back and forth, went for a very gentle ride around neighborhood until it warmed up well and then parked the car on even surface while idling and kept adding fluid until I thought it reached top of the mark. I had trouble telling where I was at but I though I finally had it.

Today, I measured it again with the car completely cold and it looks like it's way way over the mark - if anything, it should be under the MAX since it's cold.

The trouble I'm having is that it's hard to tell because I can't accurately tell from the dipstick where the top of the fluid is... it's got wet spots along nearly its entire lenght so it's really hard for me to tell what the true level is...

Any tips will be appreciated.
James

tangofox007 · #2 08-23-2010, 05:11 PM

Quote:

Originally Posted by MercFan

I
The trouble I'm having is that it's hard to tell because I can't accurately tell from the dipstick where the top of the fluid is... it's got wet spots along nearly its entire lenght so it's really hard for me to tell what the true level is...

Try letting the car sit for 10-15 minutes after you have driven it 15 or so miles. Then start it the engine, shift through the gears and leave it idling in park or neutral.

That said, my hot-cold readings are not in agreement with the spec. If it's at the "max" mark hot, it's 10mm below the "min" line when cold. The spec is 5mm below when cold.

MercFan · #3 08-23-2010, 05:19 PM

Quote:

Originally Posted by tangofox007

Try letting the car sit for 10-15 minutes after you have driven it 15 or so miles. Then start it the engine, shift through the gears and leave it idling in park or neutral.

That said, my hot-cold readings are not in agreement with the spec. If it's at the "max" mark hot, it's 10mm below the "min" line when cold. The spec is 5mm below when cold.

So you're able to wipe the dipstick clean and dip it in the tranny, then pull it out and get a consistent reading, eh? Hmmm... mine is all over the place and I can't tell what's what... I'll try what you suggested I'm just afraid I've got too much fluid in there now - don't wanna ruin the tranny by chasing it for 15 miles with too much fluid in there...

toddyvol · #4 08-23-2010, 05:24 PM

Mine is PIA to measure also. Looks like there is no easy way to get an accurate reading.

sixto · #5 08-23-2010, 09:22 PM

The filling process calls for 'pre-topping' the transmission with the engine running until the fluid level is about 10mm below the min mark on the dipstick. The actual distance varies by year and model per the FSM. Then get the transmission fluid to operating temperature. This requires a proper 20 minute drive, not idling the engine, not an easy drive around the block. As a rule of thumb, fluid at operating temperature (~180*F) is too hot to hold but a quick touch won't burn you. If you can keep your fingers pinched on the wet tip of the dipstick with fluid at operating temperature, it's either not hot enough or you're a masochist. When you're sure the fluid is hot, check the fluid level and top off as necessary. You shouldn't need to add more than a cup of fluid if you got the cold pre-topping right.

Sixto
87 300D

babymog · #6 08-24-2010, 12:55 PM

As soon as you pull the stick, you get fluid in the tube. You wipe, put the stick back in, ... the 2nd and 3rd time you have more fluid slowly running down the tube.

Patience is required.

MercFan · #7 08-24-2010, 01:31 PM

Quote:

Originally Posted by babymog

As soon as you pull the stick, you get fluid in the tube. You wipe, put the stick back in, ... the 2nd and 3rd time you have more fluid slowly running down the tube....

Exactly... so I guess you're saying I have to get the reading on the first pull, eh?

babymog · #8 08-24-2010, 04:07 PM

When it's good and hot, the fluid runs down the tube fairly quickly. I just pull the stick and wait a minute before I stick it back in for a check. Sometimes works, sometimes doesn't, not a perfect system. If you're going to try again, wait another minute or three, rapid re-checks have never yielded useful results in my experience.

mach0415 · #9 08-24-2010, 04:40 PM

This sloppy stick problem is common to most all automatics. I ALWAYS fill, let warm up, remove the stick for a few minutes and recheck it hot. Repeat as necessary. This seems to work pretty well. Good luck!

pmckechnie · #10 08-24-2010, 04:40 PM

I don't know if this is the correct way to do it but this is what I have been doing for years. Engine running, pull and wipe stick,re-insert stick, remove stick and look for the lowest clean place on the stick. Look at both sides. There will be oil higher up on the stick, but ignore it. The lowest clean spot will be the actual level in the trans. Try it and see what it does and let us know.
Also, try this and let me know what you see. Engine off, check the oil, but when you put the stick back in, pull it out quickly. Look at the level. Now, do it again but leave the stick in for 10 seconds before pulling it back out. Do you see a difference?

Paul

MercFan · #11 08-24-2010, 06:37 PM

Quote:

Originally Posted by pmckechnie

I don't know if this is the correct way to do it but this is what I have been doing for years. Engine running, pull and wipe stick,re-insert stick, remove stick and look for the lowest clean place on the stick. Look at both sides. There will be oil higher up on the stick, but ignore it. The lowest clean spot will be the actual level in the trans. Try it and see what it does and let us know.
Also, try this and let me know what you see. Engine off, check the oil, but when you put the stick back in, pull it out quickly. Look at the level. Now, do it again but leave the stick in for 10 seconds before pulling it back out. Do you see a difference?

Paul

Makes sense - I'm out of town currently (again) but first chance I'll get I'll try it. Many thanks!

MercFan · #12 08-24-2010, 06:41 PM

I'm guessing that I'll need to be reasonably sure that the level is close to the proper mark before I run it for 20 mi?! What's the chance that I'll risk damaging the transmission while I'm trying to get it to the operating temp... right (because of overfill condition)?!

I'm just a little paranoid about it now...

NoSparkNeeded · #13 08-24-2010, 07:56 PM

I've been doing my own car work since I was 15. This has bothered me for years checking the level on auto trannies. I always pull the stick, wait a couple minutes, count 'em, wipe the stick, plunge it in, pull it quickly and try to see where it has a consistant amount of fluid on it. Look at both sides. This has always amazed me that they say level is so critical, but leaves so much to"intuition", to asses the proper level. If you have done it many times, you see it right away. One of my motorcycles had a nice sight glass. No Hot /Cold "estimation" stick, hehe. So don't feel alone, at some point you "get the feel". So don't forget, if you are teaching your wife how to do this, that MB has that latching dipstick, so you don't look like an idiot when you cannot even pull it out,hehhe

JHZR2 · #14 08-24-2010, 10:18 PM

My typical issue is that I get a different fluid height on one side than the other. Is the lower level truly the correct reading?

mplafleur · #15 08-25-2010, 01:23 AM

Everytime I wipe the dipstick and pull it back out I seem to get a different result. It is very difficult to find a definite mark as so much fluid is on the filler tube walls.