Question about auto transmission fluid

[suiteR]

My friend's 320CE convertible (W124) has strange transmission performance. At "D", starts to accelerate, the transmission stays on the same gear until the engine rev high enough to about 3000 - 4000 rpm, then shift to the next gear.

So we decided to take some time this evening to drain the ATF, remove oil pan, replace the sump filter, gasket, and refill with the same amount of ATF (MB fluid). But the problem still exists.

There's an ATF dipstick, with "30" and "80" degree-C reading.
I am confused about the necessary quantity... I drained about 4L of fluid, thus I refilled with 4L at the moment.

Can someone advise me how to read the dipstick to determine if the ATF is sufficient w/in the system. Should I check the ATF level with engine running? At "P" or "N" gear?

or is it a sign of transmission failure in the near future?

[Jackd]

To check transmission oil level:
Put the car on a level surface.
Leave the engine running, in park
Pull the dip-stick.
The 30-80 are for cold/hot condition. If the car has been running for a while and has reached its normal operating temperature, take the reading versus the 80 mark.
Your shifting problem could be a faulty/disconnected modulator (located on the left side of the transmission)

jackD

[suiteR]

Thanks for your helpful comments!
I found that when the engine is running, the fluid level is above the 80 mark. Will too much fluid causes the symtom?

[suiteR]

Your shifting problem could be a faulty/disconnected modulator (located on the left side of the transmission)

Jackd, may I ask... if my friend's car is right-side steering, will the modulator be located differently? How does it look like? We'll try to lift up the car and check...

[Jackd]

The modulator is still on the left side of the car, even on those with the steering column ''on the wrong side'' of the car.
The modulator has a vacuum line attached to it. It should be fairly easy to find as it si the only thing with a vacuum line on the transmission.
JackD

[suiteR]

Tks, I will look for it...