Mercedes Benz 300D (W123 series): Manual Transmission to Automatic Transmission.

wartikars · 25th December 2009, 15:32

Hi friends,
Need advice for the following points with respect to my Mercedes Benz 300D (W123 series).

I want to convert my manual transmission 300D to an automatic transmission:

Is it possible?
Is it advisable?
How much would be the fuel consumption?
How much would the conversion cost?
Does anyone know who can do it in Mumbai/Pune?

Best regards.

wartikars · 20th September 2010, 11:00

I tried searching for topics related to my query but did not find any.

I want to change the Manual Transmission of my Mercedes Benz 300D W123 to an Auto Transmission. My grarage owner has a Mercedes Benz 240D W123 with Auto Transmission. He wants to change his car to Manual Transmission. He has given me an exchange offer. Please advice me if I should go ahead with the exhange. What are the pros & cons of fitting a 240D auto transmission to a 300D?

msaudf · 13th October 2010, 11:07

my humble suggestion is that you stick with your manual transmission.even if it is broken fix it and it will still last you another generation.
if you want an auto transmission car, its best to buy one that came with a factory fitted auto transmission.
the reason i dont recommend the transplant is because, the auto transmission in these cars are controlled by vacuum modulators, so installing an auto transmission involves poking around with the vacuum system which always turns out to be a head ache if you dont have the correct diagrams, let alone the expertise.
and on top of all that the drop in fuel efficiency by about 3 kilometers/liter.
messing around with the shifter assembly.
oh and most importantly its a bit slow.
i just saw your question about the cost of conversion.
the person who wants to do the exchange is gaining out of the deal so he should pay you.

chargerman · 21st September 2013, 22:45

you can go for the conversion, its the same gearbox between 240D and 300D

chargerman · 21st September 2013, 22:52

just realized its a 3 year old thread! lol

BowMan · 3rd January 2014, 12:39

I am about the check a potential w123 buy but have been informed by the seller that the transmission (4speed manual) has a humming noise.

From my (somewhat limited) DIY experience it seems like a badly worn bearing in the tranny. Could be input shaft bearing, main drive bearing counter shaft bearing...??? This could mean a neglected car which has not seen frequent oil changes. But of course this would need a physical examination.

Can any of you tell me if you have had similar experience with your w123 trannys and what was the diagnosis and what was the cost involved?

I am a bit worried because the owner informed me that he replaced the tranny from a donor car? Does this mean it is cheaper/smarter to do that rather than fix a couple of worn bearings? Or there could be other issues lurking under?

25th December 2009, 15:32	#1
wartikars BHPian Join Date: Nov 2009 Location: Pune Posts: 168 Thanked: 12 Times View My Garage	Mercedes Benz 300D (W123 series): Manual Transmission to Automatic Transmission. Hi friends, Need advice for the following points with respect to my Mercedes Benz 300D (W123 series). I want to convert my manual transmission 300D to an automatic transmission: Is it possible? Is it advisable? How much would be the fuel consumption? How much would the conversion cost? Does anyone know who can do it in Mumbai/Pune? Best regards.
	() Thanks

20th September 2010, 11:00	#2
wartikars BHPian Join Date: Nov 2009 Location: Pune Posts: 168 Thanked: 12 Times View My Garage	Need Advice: Fitting of Automatic Transmission in the 300D W123 I tried searching for topics related to my query but did not find any. I want to change the Manual Transmission of my Mercedes Benz 300D W123 to an Auto Transmission. My grarage owner has a Mercedes Benz 240D W123 with Auto Transmission. He wants to change his car to Manual Transmission. He has given me an exchange offer. Please advice me if I should go ahead with the exhange. What are the pros & cons of fitting a 240D auto transmission to a 300D? Last edited by wartikars : 20th September 2010 at 11:19.
	() Thanks

13th October 2010, 11:07	#3
msaudf BHPian Join Date: Jan 2009 Location: Cochin Posts: 269 Thanked: 164 Times	my humble suggestion is that you stick with your manual transmission.even if it is broken fix it and it will still last you another generation. if you want an auto transmission car, its best to buy one that came with a factory fitted auto transmission. the reason i dont recommend the transplant is because, the auto transmission in these cars are controlled by vacuum modulators, so installing an auto transmission involves poking around with the vacuum system which always turns out to be a head ache if you dont have the correct diagrams, let alone the expertise. and on top of all that the drop in fuel efficiency by about 3 kilometers/liter. messing around with the shifter assembly. oh and most importantly its a bit slow. i just saw your question about the cost of conversion. the person who wants to do the exchange is gaining out of the deal so he should pay you. Last edited by msaudf : 13th October 2010 at 11:14.
	(2) Thanks

21st September 2013, 22:45	#4
chargerman BHPian Join Date: Aug 2004 Location: Dhaka, Bangladesh Posts: 242 Thanked: 195 Times	Re: Mercedes Benz 300D (W123 series): Manual Transmission to Automatic Transmission. you can go for the conversion, its the same gearbox between 240D and 300D
	(1) Thanks

21st September 2013, 22:52	#5
chargerman BHPian Join Date: Aug 2004 Location: Dhaka, Bangladesh Posts: 242 Thanked: 195 Times	Re: Mercedes Benz 300D (W123 series): Manual Transmission to Automatic Transmission. just realized its a 3 year old thread! lol
	(1) Thanks

3rd January 2014, 12:39	#6
BowMan BHPian Join Date: Dec 2013 Location: Gandhinagar Posts: 249 Thanked: 620 Times	Re: Mercedes Benz 300D (W123 series): Manual Transmission to Automatic Transmission. I am about the check a potential w123 buy but have been informed by the seller that the transmission (4speed manual) has a humming noise. From my (somewhat limited) DIY experience it seems like a badly worn bearing in the tranny. Could be input shaft bearing, main drive bearing counter shaft bearing...??? This could mean a neglected car which has not seen frequent oil changes. But of course this would need a physical examination. Can any of you tell me if you have had similar experience with your w123 trannys and what was the diagnosis and what was the cost involved? I am a bit worried because the owner informed me that he replaced the tranny from a donor car? Does this mean it is cheaper/smarter to do that rather than fix a couple of worn bearings? Or there could be other issues lurking under?
	() Thanks