Hello everyone,

When I do want to accelerate hard (say merging on the freeway) my transmission shifts, but only (it seems) into 3rd gear. It only shifts into 4th when I ease my foot off of the accelerator. Is this normal? Does this mean that I need to adjust the bowden cables or replace the kick down switch? Any insight would be helpful. Thanks!

- DC Josh

check your fluid... drive the car until it is at full temp, leave it running. Take transmission stick out, wipe clean, put back in, take measurement. Make sure its in between the marks and very clean. If dirty at all, do a full flush.

Very normal.

What makes it normal? Can you explain what is happening? I don't feel this when the automatic on my Jeep shifts.

It shouldn't hold in 3rd forever (with the accelerator pressed down) at some point it should shift to 4th. If you look on your speedometer there are notches indicating the speeds that should not be exceeded in each gear (1 notch for 1st; 2 notches for 2nd etc)

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Assuming your Jeep is a relatively newer vehicle, the answer is that comparing its transmission functioning to that of the transmission in your Mercedes is like comparing a smartphone to a 1970s desk telephone in terms of technology.

The Jeep likely has a sensors connected to electronic controllers that govern how it decides what gear to be in, and how it shifts. The Mercedes only has a mechanical input for shift point, namely a Bowden cable connected to the throttle linkage, which runs into the transmission.

When you have the throttle depressed while accelerating this cable is telling the trans not to shift up. Once you have reached speed your release of pressure on the go pedal, the cable moves and the trans shifts up.

What your car is doing is what it was designed to do, given the technology. It is holding 3rd gear to give you maximum acceleration.

If the adjuster on the Bowden cable breaks, and the cable doesn't move normally, you have the opposite situation -- the trans will shift itself all the way up into 4th at about 35 mph.

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

I will get back to you as soon as I figure out how to shift my 300D into 4 Lo. My Jeeps have a lever for that; don't where they put that thing in my Mercedes.

Any idea why my 300D doors don't just pull off or the top won't fold down?

If it is a Mercedes Transmission

Transmission Vacuum Modulator Adjustment
PeachPartsWiki: Transmission Vacuum Modulator Adjustment

Transmission Vacuum and adjustments
Mercedes-Benz Transmission, Steve Brotherton, ImportCar, February 2002

Is you Kick Down Switch working properly?

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84 300D, 82 Volvo 244Gl Diesel

I found out when my transmission was replaced (previous owner)that they put wayyy to much trans fluid in as in 10oz to much. I followed this document and was skeptical that going below the min mark was safe, but the car runs much smoother at the levels they suggest. Also the trans fluid has remained the blood red color. Now I believe I have to still fine adjust the vacuum mod.

Attached Files

2710 - Automatic transmission, checking & correcting fluid level.pdf (163.4 KB, 122 views)