Would an overfilled trans .... - PeachParts Mercedes-Benz Forum

haasman · #1 09-13-2003, 05:29 PM

.... cause it to not move forward or back?

Trying to help some friends who's 85 500SEL has been sitting for over a year. They want to sell it, 113k miles.

Before even trying to start it I checked the ATF level and it was at least an inch over the upper fill mark! Sooooo .... I will remove the excess ATF ... add oil, charge the battery ... etc.

But to the question: Would this existing overfill prevent it from moving?

Haasman

#2 09-13-2003, 06:30 PM

No. Are you going to put it into neutral and roll it out? If not, I wouldn't drive too far.

Too much fluid can cause the fluid to foam, which in turn can lead to erratic shifting, oil starvation and transmission damage. Too much fluid may also force ATF to leak past the transmission seals.

engatwork · #3 09-13-2003, 06:50 PM

I would at least try to start it and run it before I removed any of the fluid. Getting an accurate reading on the transmission fluid level is an art

and I don't think it is done with the car off and cold. Being overfilled should not keep it from moving forward or backward but being too low surely can.

Was it operating properly when it was parked or has anyone added fluid to it to cause it to be too full?

adrianruk · #4 09-13-2003, 06:52 PM

You must not take any notice of the ATF level without the engine running - the oil from the torque converter and the oilways drains down and gives a totally false reading. Start the engine and let it run for a while, putting the trans through all its positions, before checking the level, with engine running in N or P - it will probably be OK
Adrian

haasman · #5 09-13-2003, 07:38 PM

Thanks! I will check the fluid again once we get it running. I cant remember ever seeing ATF so high on a dipstick before.

Prior to not using it they had complained about no reverse but said it did have forward gears.

I'll post the results.

Haasman

psfred · #6 09-13-2003, 07:57 PM

On prolonged sitting, enough fluid can drain out of the torque converter to spill out the vent -- you can lose up to a quart this way. Looks way overfull or as if you have a bad leak, but it's just overflow.

This drives my mechanic friend nuts -- he has a customer with a 68 280SL, beautiful car, but he refuses to drive it except to bring it in to "get the transmission leak fixed" every year or so when it starts to drip again. Totally preventable by just starting the bloody thing once a month or so, but hey you can't tell some people anything at all!

Peter

haasman · #7 09-13-2003, 08:12 PM

Thanks Peter. The car has been sitting in the drive with the nose slightly up hill. It will be interesting to see what happens to the fluid level once is starts.

I won't delete or add (of course) until it has been running a few minutes and I move the shifter around.

Haasman

haasman · #8 09-14-2003, 05:43 PM

... the answer is:

The car had been sitting for over a year. It looks like the ATF "drained back" into the trans.

Got the car running and then checked the AFT level-it needed 3 quarts.

When I first got it running the trans would not engage in reverse or any of the forward speeds. I started adding ATF and soon I got gears. Car is now running and shifting well.

So...

-no it wasn't overfilled, the ATF had simply drained into the trans (car was parked on a slightly sloping driveway)
-The car needed ATF
-The car shifts well after a final adding of fluid once warm

My friends think I am a hero. Nice.

Haasman

psfred · #9 09-14-2003, 06:36 PM

Isn't it nice to be smart and appreciated? Even if it is only knowledge passed on from someone else, it's fun to be correct!

Peter

xp190 · #10 09-14-2003, 10:43 PM

I still haven't figured out how to read the tranny dipstick and it drives me nuts, why can't it be as easy as engine oil dipstick?

I use a different method now however, I put new fluid in and overfill, then I stick a tube down the dip stick pipe and put its tip right where the correct level should be and suck out anything excessive, when air starts coming through, I got the right level, even though I can never see it on the dip stick itself correctly.

xp

psfred · #11 09-14-2003, 11:17 PM

XP:

It's tricky. You must have the dipstick right way round, as fluid almost always drags up one side of the tube and wipes off on the stick the next time. Best way is to pull the dipstick, then wait a minute or so after wiping it off to allow the fluid dragged up the side of the tube to drain back down.

Re-instert stick, allow to stand for 20 sec or so for the fluid to "climb" up, then pull and read BOTH sides. The one with a line of fluid perpendicular to the side of the stick is the level. May be on the marked side, may not. That's the reason for getting the stick right way round -- if the marked side is covered with fluid and the other side indicates level, you must rotate it 180 degrees when you put it back in. I never remember, just read the side where the fluid level is.

Complicating the issue is that some dipsticks are marked for both hot and cold fill -- cold mark is always lower than the hot mark.

I'd rather read the dipstick six times filling up that burning the tranny up!

By the way, did you ever fix the thump in the rear of your 190?

Peter

joel · #12 09-14-2003, 11:24 PM

Quote "Even if it is only knowledge passed on from someone else, it's fun to be correct!Unquote

Isn't it all knowledge (learning) are all acquired from
someone else!!

psfred · #13 09-14-2003, 11:47 PM

Well, not always. Every once in a while someone stumbles over something new, but I'm a scientist, it really needs to be verified before it becomes knowledge, so I would have to say you are correct.

It's the ability to take knowledge and apply it that leads to progress.

Peter

haasman · #14 09-15-2003, 03:05 AM

Quote:

Isn't it nice to be smart and appreciated? Even if it is only knowledge passed on from someone else, it's fun to be correct!

I do enjoy helping out most often. A lot of people have shared their knowledge with me and I like passing it on.

I am finding trusting my repair intuition more and more pays off.

I find that often with these cars, what seems like a looming major repair often can be corrected with careful analysis and doing just what is needed to fix the problem.

It is very helpful with the identical design solutions from car to car. For an example 201's and the 124's both having cable rear window winders, similiar door checks, suspensions etc.

Haasman