I have a 1980 240D with a standard transmission. I am thinking of buying a 1982 240D with a blown engine and an automatic transmission. My car has a rough body and interior, the 82 is in great condition.

Can someone tell me if my engine will fit without modification into the 82? How about my manual transmission, clutch pedal etc? How difficult is this conversion? Must I change the drive shaft or rear end?

On the other hand, what is involved in mating my engine to the automatic transmission in the '82. Is this a better or worse idea.

A transplant seems like a good idea to me; would anyone with specific experience care to burst my bubble? Any constructive advice, pro or con, would be greatly appreciated.

Ken Mitchell

A time consuming direct bolt-in job! You will be happy with results.I have done several auto/stick swaps, the donor car is important. Have fun!

The conversion to std shift is only a bunch of work. The differentials will be different ratio, so you might want to change it too. I would probably change the whole driveshaft as changing only the front half can lead to vibration problems (always mark the two driveshaft sections so they can be installed exactly the same way).

As to the std engine in an automatic; I can tell you that it works. I have done many. I can also tell you that according to the parts it shouldn't work. There are different crankshafts for std trans versus automatic. I am not sure what the differences are but here are two possibilities. First the end of the crank either supports a pilot bearing for clutch cars or the nose of the torque convertor on automatics. I have gone both ways and haven't seen the problem.

The second possible difference is the motor balance. The engine manual used to show how to balance the new flywheel to the old one when being replaced. In other words they weren't individually balanced. If this is the case there ought to be the possibility of great imbalance because of the differences in flywheel weight std vrs auto. Again, I have seen no noticable extra vibration but thats an ambiguous situation with a diesel (bg).

The easiest thing to do would be to install the motor only and see how it works. If there are balance problems it is virtually no extra labor to finish the conversion (compared to what would have been extra to do it in the first place).

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

Ken,

I recently did something simiar. I took an early engine and mated it to a late transmission. Here's what I learned that may be helpful to you.

First of all, I think you will find the 1980 car to have series glow plugs, while the '82 has pin type, parallel glow plugs, the glow plug relays are in different locations and totally incompatible. If you want to put the series glow plug engine in the parallel glow plug chassis, it will be a hassle to switch around the wiring and do a neat, clean and reliable job.

My transplant was a temporary one, my plan was to use the '80 engine temporarily while rebuilding the original engine to be replaced into the car later. So, my solution for the glow plug problem was sound, but most folks probably would not want to do something like this for a permanent installation. I put a momentary contact window switch in the panel at the top above the radio. I connected this switch to a Ford starter relay, because their cheap, rugged and easy to find anywhere. I then took a heavy cable from the relay to an 80 Amp glow plug fuse mounted behind the engine in the same location you would find on the '80 model. To start the car, I hold down the button with ignition on(I wired the relay primary side from a fuse in the box which is hot only with ignition on) for about 12 or 15 seconds in the summer and up to about 35 or 40 seconds in the winter.

Next issue. I would expect that there are different rear axle ratios in these cars. I would check this out. You can simply raise the rear of the car and count number of driveshaft revoutions for one rear wheel revolution. If they are different, you should consider changing the rear axle. You may have to change the driveshaft, crossmember and other components, but this should not be a big deal.

Changing the clutch linkage should not be a huge problem. The hydraulic nature should make this easier than changing a mechanical linkage. You may have to take the entire pedal assembly, I have no idea how much trouble this will be.

The next thing is mating the manual transmission engine to the automatic transmission. I ran into something similar mating an early engine to a late transmission that I believe directly applies here. There is an adapter plate bolted to the engine which then bolts to the appropriate transmission. If you remove the flywheel or flexplate, you can then remove the appropriate plate and transfer it to the other engine. I expect that both pilot bearings are the same, but it wouldn't hurt to check it closely.

I'm a manual transmission fanatic, so if it were me, I would go to whatever lengths to retain the 4 Speed, but that is of course a personal thing.

Also, these may have different A/C compressors. This should be no problem. Unbolt the compressor from the engine leaving it connected without breaking any AC lines, and wire it out of the way until you get the engine in place. If it is different, it will still bolt in place on the engine being transplanted.

These are easy cars to deal with, and everything is accessible, at least in the engine compartment.

If any other questions come up during the transplant, feel free to ask.

Good luck,

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Larry Bible
'84 Euro 240D, 523K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

Can a manny tranny from a w123 240D be swapped with that of a w123 300D turbo? Is it the same bolt-on procedure as mentionsed above?

I have seen euro 300D's with 4spd manuls, but not the turbos. One would assume that the 240D and 300D shared the same trans.

I miss the 4spd gearbox in my old 240D.

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'82 300D Turbo 216k miles

I checked into this once. You're dealing with a different driveshaft and some shifter parts are different. I personally would not attempt this one unless I had ALL the pieces from a donor car, which would have to be a Euro car.

I saw a manual transmission, Euro 300D once in this country.

I'd be leary of this one.

Good luck,


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Larry Bible
'84 Euro 240D, 523K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

Since all 240D's(W123) use a 3.69/1 rear end that won't cause a problem. The drive shaft is longer(front) in the stick shift, but since you have one already that won't be a problem either. The 1980 engine uses pin-style glow plugs so that won't be a problem either. Time to swap parts will be the biggest challenge!! Have fun!

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MERCEDES BENZ MASTER GUILD TECHNICIAN (6 TIMES)
ASE MASTER TECHNICIAN
27 YEARS DEALER M.B. Shopforeman
190E 2.3 ITS RACECAR
1986 190E 16V

Thanks for all the help. I'm going this weekend to get the donor car.

Ken

MBDoc,

My donor car was an '80 Euro and had series glow plugs. My wife had an '80 US Car and it was series glow plugs. Maybe the change came in mid model year.

Good luck,


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Larry Bible
'84 Euro 240D, 523K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

All 1980 & later US cars(diesel) came w/pin type plugs. This also was the year for GM R-4 compressors on all diesels.