I am trying to solve a problem with my automatic transmission 240D. The transmission shifts perfectly when the engine is not fully warmed up. It does exactly what I want it to. After the engine temperature starts to go above the 80 degree mark on the dash gauge, the transmission begins to shift earlier and earlier. On a hot day in Atlanta, GA with the air conditioning going, the transmission will begin to shift into 2nd at 5mph and shift into 4th at 35mph with my foot on the floor. On an engine like this with no power, I can't get anywhere fast. Does anyone know why the transmission temperature would affect my shifting so much? Is this just worn seals inside the transmission?

I have read the article on all of the vacuum adjustments, but nothing really seems like it would solve my problem. The transmission works great while its warming up so I am hesitant to play adjust any vacuum signals yet.

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George Carstens

Isn't there some temp sensor on the engine? Maybe it opens/closes around 80C and causes a vacuum leak?

Try putting a T into the vacuum line to the transmission and hooking up a vacuum gauge to it. Watch what's happening to the vacuum there when it starts acting up.

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'83 300DTurbo http://badges.fuelly.com/images/smallsig-us/318559.png

Broadband: more lies faster.

Lets say theoretically (although I have not verified) that it isn't engine temperature but transmission temperature. Would this indicate worn seals inside the transmission?

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George Carstens

Put a 5 speed rock crusher in it. That will make a terrific machine.

oh man would it..

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Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac?

As long as they would add one additional commandment for you to keep thy religion to thyself.
George Carlin (Wonder where he is now..)

1981 240d (engine donor 1983 240d) recently rebuilt engine hurray! - No more.. fought a tree and the tree won.

pearl black 1983 240d 4speed (Converted!@$$%) atleast the tranny was rebuilt.

Rock crusher? What is this a Pontiac?

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1985 CA 300D Turbo , 213K mi

I'm certainly no transmission expert (just starting to learn about what makes them tick), but yes, I think that could cause it. However, I believe (perhaps incorrectly) that different kinds of ATF can cause it (different temp/viscosity behavior), perhaps even tired ATF can cause it, and there is a temp compensator on some models of transmission that might be able to fail in such a way as to cause this (but that's technically an internal part). I did notice a difference in warm/cold and general shifting behavior when I changed my ATF, but I also went to synthetic at the same time.

I assume you've verified by now that the vacuum signal sent to the tranny doesn't change behavior cold/warm, right?

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'83 300DTurbo http://badges.fuelly.com/images/smallsig-us/318559.png

Broadband: more lies faster.

I have this same problem actually. I also have a 240d, 1982. There's an issue with my vacuum system, a leak somewhere, and it causes issues with my door lock system and also with my fuel shutoff selenoid when I turn my car off. When I open the door, the car cuts off fine, probably some stop somewhere holding pressure in my system, and when I open the door it releases it apparently, or something. I'm going to try finding the issue with my vacuum system, but I really believe that that's the issue. I've noticed that the throttle linkage tht supposedly goes to my transmission according to the generic hanes manual for my type vehicle goes instead to something mounted on the IP which has vacuum lines coming off it. That was disconnected when I got it, and there was a golf tee in blocking a vacuum line going to a check valve which I believe passed through to the door locks so that the previous owner could bypass the door and fuel cutoff issue, but I'm looking to try to find the issue and fix it when I have the time. I'll keep you posted on my progress and if it helps. But I did a ATF fluid and filter change and it didn't help in the least. and like you, it has to do with the temperature.

Also, try this link I found on another thread and let me know if it helps. http://www.peachparts.com/Wikka/TransVacTune

Also, as an aid, check out this diagram: http://www.peterschmid.com/vacuum/1977_1985/616_617_91/616_617_91.jpg

Muncie rock crushers. the gear teeth and syncros infact everything i can think of are made out of hardened steel. extremely strong trannys last forever. in fact they call them "rock crushers" because your supposed to shift them without depressing the clutch. (http://seattle.craigslist.org/see/pts/321452553.html) a look inside of one.

__________________
Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac?

As long as they would add one additional commandment for you to keep thy religion to thyself.
George Carlin (Wonder where he is now..)

1981 240d (engine donor 1983 240d) recently rebuilt engine hurray! - No more.. fought a tree and the tree won.

pearl black 1983 240d 4speed (Converted!@$$%) atleast the tranny was rebuilt.

I found out there were a few leaks, mostly occuring in the door lock and unlock controls. I bypassed them and did a mod to the system so that the fuel cutoff selenoid will be cut off by the vacuum chamber in the back when I cut my car off, thus getting rid of the door issues and fixing my fuel cutoff till I have time to redo that. I also replaced some of the lines going to my egr valve and their connectors, which had started to dry rot I guess you ould call it. Now everything is good as far as the lines, only 1 part to replace, it came in thye mail today, and then I'll do the final adjustments, but it's already feeling a lot better as far as shifting. More updates soon when the weather is better and I can finish my work on it.