Why does my 1980 300SD start in 2nd Gear? No, it's not supposed to.

gtl diesel · 06-11-2008, 03:19 AM

My 1980 MBZ 300SD starts in 2nd gear and WILL NOT kick down in to 1st gear, although all other kickdown functions are normal. In other words, something is preventing the trans from its normal starting point (first gear) and making this a 3 speed tranny, not a 4 speed. I do notice that the tranny seems overfilled, could that be a cause? All other aspects of transmission operation are normal. Car runs perfectly (has ony 134k miles).

All replies will be appreciated.

Thanks,
Norm

Untertürkheim · 06-11-2008, 04:20 AM

Are you sure that it is a 4-speed transmission in the car i.e. have you been able to use all 4 gears at some point? It is possible that the transmission was replaced with the 3 speed from the 450 engine model.

240D 3.0T · 06-11-2008, 03:50 PM

All of MB's post 60's Diesels came with a 4-speed.

Overfilling will cause foaming and valve body problems.

Untertürkheim · 06-11-2008, 04:48 PM

[quote=240D 3.0T;2877434]All of MB's post 60's Diesels came with a 4-speed. QUOTE]

I know the car came with a 4-speed, but is it possible someone replaced it with the 3-speed from the M117 model?

gtl diesel · 06-12-2008, 02:24 AM

[quote=Untertürkheim;2877649]

Quote:

Originally Posted by 240D 3.0T

All of MB's post 60's Diesels came with a 4-speed. QUOTE]

I know the car came with a 4-speed, but is it possible someone replaced it with the 3-speed from the M117 model?

OK, thanks for the replies. This car still has the original transmission 722-120. Verified. It is a 4 speed designed to start in 1st. I drained and readjusted the fluid level and it made no difference at all. My suspicion is that there is either a clog or a broken element (piston? spring?) inside the valve body. Any tranny guys out there care to comment? Anyone know where I can get a diagram or a tech book on this transmission.

Thanks.Norm

lkchris · 06-27-2008, 06:15 PM

So the four-speeds in W123 and all W124 until about 1990 were designed to start in 2nd.

You're saying the S-class got this feature 10 years earlier?

06-11-2008, 03:19 AM	#1
gtl diesel Newbie Join Date: Jun 2007 Location: San Diego County Posts: 23	Why does my 1980 300SD start in 2nd Gear? No, it's not supposed to. My 1980 MBZ 300SD starts in 2nd gear and WILL NOT kick down in to 1st gear, although all other kickdown functions are normal. In other words, something is preventing the trans from its normal starting point (first gear) and making this a 3 speed tranny, not a 4 speed. I do notice that the tranny seems overfilled, could that be a cause? All other aspects of transmission operation are normal. Car runs perfectly (has ony 134k miles). All replies will be appreciated. Thanks, Norm

06-27-2008, 06:15 PM	#6
lkchris MBWorld Fanatic! Join Date: Sep 2005 Location: Albuquerque Posts: 2,818	So the four-speeds in W123 and all W124 until about 1990 were designed to start in 2nd. You're saying the S-class got this feature 10 years earlier? __________________ Kent Christensen Albuquerque '07 GL320CDI, '06 E320CDI

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06-11-2008, 04:20 AM	#2
Untertürkheim MBWorld Fanatic! Join Date: Mar 2007 Posts: 2,206	Are you sure that it is a 4-speed transmission in the car i.e. have you been able to use all 4 gears at some point? It is possible that the transmission was replaced with the 3 speed from the 450 engine model.

06-11-2008, 03:50 PM	#3
240D 3.0T Banned Join Date: Apr 2006 Location: Federal Heights, CO Posts: 507	All of MB's post 60's Diesels came with a 4-speed. Overfilling will cause foaming and valve body problems.

06-11-2008, 04:48 PM	#4
Untertürkheim MBWorld Fanatic! Join Date: Mar 2007 Posts: 2,206	[quote=240D 3.0T;2877434]All of MB's post 60's Diesels came with a 4-speed. QUOTE] I know the car came with a 4-speed, but is it possible someone replaced it with the 3-speed from the M117 model?