280sel engine/transmission into 280sl

[Sven]

I know this has been covered a million times, but have secured a strong running 1970 280SEL (2.8, AT) to use as an engine donor car for my 1968 280sl with AT.  I know the engines are nearly identical and can be swapped painlessly.  

How about the transmissions? Are they interchangable?  My sl has never run since I owned it, so I don't know that status of the tranmission. Experts tell me the sl's transmission is relatively bullet-proof, but you never know.  It makes sense to me to change both engine and trans because I know both are working properly.  

Any thoughts or wisdom?

[ja17]

Hello Sven,
All W113 cars and many of the early Mercedes sedans coupes and convertibles had the K4A025 automatic transmission. It is most easily identified by the 16 bolt oil pan. However sometime in 1968 or 1969 all other Mercedes models except for the W113 changed to the new automatic transmission design (K4C025). Identify this type by the four bolt transmission pan.

Your 1970 280SEL donor car will have the incorrect 4 bolt pan transmission. This transmission will NOT adapt to the W113 without a lot of real modifications. However your original W113 transmission will bolt up to the 280SE engine without much difficulty. You will need to switch and use from your W113 the following; Engine/transmission mating plate, possibly flywheel, the original W113 automatic, use the sedan starter it has more horsepower. Be sure to unhook the torque converters from the flywheels before removing the transmissions so you do not damage the front transmission pumps. The change over should be fairly easy. Make sure your three position solenoid and linkage work properly before re-installing the original W113 transmission. there may be one or two  other very minor items but it this is not a big deal and should go smoothly. Check back for more details if you get into the project.

Good Luck!


Joe Alexander
Blacklick, Ohio

[rwmastel]

Joe,

Can he leave the newer engine/transmission combo together?  I guess, will the newer transmission fit in the W113 transmission tunnel?  Would there be a drive shaft issue?

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[Naj ✝︎]

Joe,

quote: use the sedan starter it has more horsepower

Is there any discernable difference in cranking speed?

naj

65 230SL
68 280SL

[ja17]

Hello Rodd,
The later transmission is physically a different size, I am not sure it would fit. Yes there are driveshaft issues,   linkage issues but it could be a worthwhile project to try out.

Naj,
Yes the extra horse power of the starter really spins the engine faster. I recommend this upgrade in any pre 1969 W113.

Joe Alexander
Blacklick, Ohio

[Naj ✝︎]

Thanks, Joe,
I'll be replacing the starters soon, hoping they will fit!! :oops:
The starter solenoid on right hand drive cars is closer to the engine block than left hand drive starters. I believe this was done to accomodate the steering box on the right. There seems to be enough room there to take the left hand starter.
Suck it and see??
Note distance between bolt hole and solenoid mount:
Download Attachment: StarterLhRh01.JPG
43.56 KB

naj

[hands_aus]

Hey Joe,
The auto-trans in my 250 SL says it is a GA230sl*E  
Is that the same as the K4A025 auto-trans?

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[ja17]

Hello Bob,
Yes, this is the early version of the K4A025 (notice the 16 bolt oil pan). From what I can decifer, the later version also type K4A025 (16 bolt also) is physically the same but has a slightly different valve body in the transmission. This later version of the K4A025 is identified by "GA 280 SE" label. Both these units are basically the same and are interchangable.

The early K40A025 "GA 230 SL-E" was used in models 230SL, 250S (up to chasis #3651), 250SE, 250SL, 250S/8.

The latter version K4A025 "GA 280 SE" was used in models 280S/8 (early models only), 280SE/8 early models only), 280SL/8 (all), 300SEL/8 (early six cylinders only with).

A new K4C025 (4 bolt pan) replaced the K4A025 transmission in all the later models except for the W113 which kept the (16 bolt) K4A025 until the end of production.



Joe Alexander
Blacklick, Ohio

[hands_aus]

Hey Joe,

Great info!

Thanks, mate

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[Sven]

Joe,

I'll second that thanks!

sven