Possible Engine Swap (617 to 616) / Body Swap - PeachParts Mercedes-Benz Forum

BradenFinney · #1 12-24-2021, 12:15 AM

Hello,

As silly as this may seem, I have a question about swapping a 4 cyl 616 engine into a car originally with a 5 cyl 617 (with turbo).

The background is that I have a 1982 240D that ran and drove perfectly. Automatic transmission, 616 engine, no complaints. Unfortunately it was wrecked and the inner/outer driver's fender, hood, and radiator core support metal work all need replacement. Also add to it the glowplug relay wiring, headlamp wiring, and a few other odds and ends from the wreck. The transmission linkage is also now misaligned (can't find neutral from inside the car). Everything else seems okay and the car can still run and drive.

I have found, after two years, a donor car in the right price range. It is a W123 300D turbodiesel (four door, not a wagon). The body is in "perfect" shape for a 1983 car (similar amount of rust spots to my 240). This car has a complete 5 cylinder engine and turbo, but I was told it has no compression. Assuming we discount this engine as a total loss (which is probably premature), I have two options:

1) Cut apart the perfect 300D body and slap it onto the 240D. I have 0 experience hacking apart bodywork and no welding experience. I don't really like this option.

2) Remove the 4cyl, the auto transmission, and the rear axle from the 240D and slap it into the 300D. If I go this option, given that I have all the body components of both cars, am I likely to run into any issues? All I can find on the forums is fitting the 5cyl into the 4 cyl space. I assume that my complete drivetrain would drop in, but I am a little uncertain with how the subframe/ engine mounts will line up. Were there two factory positions drilled into the car to specify where to place the subframe/mounts? I want to make sure that I'm not missing anything major or that I would need to source any other parts to make the conversion work.

I know that aside from the powertrain differences, the 300 and 240 have "gizmo" differences (manual windows in my 240, sunroof and electronic windows in the 300).

Any guidance on this would be greatly appreciated!

engatwork · #2 12-24-2021, 06:00 AM

Should not be an issue. I'd swap both engine and transmission. You may need the driveshaft from the 300D too.

BradenFinney · #3 12-24-2021, 03:43 PM

Quote:

Originally Posted by engatwork

Should not be an issue. I'd swap both engine and transmission. You may need the driveshaft from the 300D too.

You mean the drive shaft from the 240D, right? I would be trying to put the entire drive unit from the 240D into the 300D body.

I assume the exhaust from the 240D has to follow as well?

engatwork · #4 12-24-2021, 04:14 PM

Yea, after thinking about it just pay attention to the 240D versus 300D driveshaft length. They should be same, I'm just not sure whether both cars share same tranny. I'd try to keep the 300D transmission with the 300D engine.

BradenFinney · #5 12-24-2021, 04:20 PM

Thanks for the replies.

I know the 5 cyl engine has the shorter driveshaft. Also, the trans crossmember is probably set back 4 inches or so versus the 240 engine.

Not sure what I plan on doing with the "presumed dead" 300D engine and transmission, but I would try to drop the whole entire 240 powertrain over (204 engine, trans, drive shaft, trans subframe, exhaust, rear diff) to the 300 body.

t walgamuth · #6 12-24-2021, 11:56 PM

You need to switch the entire drive train over...plus the radiator and oil cooler. This includes the trans mount. The rear drive shaft will be the same so no need to switch it over. You also need to change the speedo and the shift linkage.

BradenFinney · #7 12-25-2021, 12:35 AM

Quote:

Originally Posted by t walgamuth

You need to switch the entire drive train over...plus the radiator and oil cooler. This includes the trans mount. The rear drive shaft will be the same so no need to switch it over. You also need to change the speedo and the shift linkage.

Do you happen to know if there are bolt holes for moving the trans mount? Or do I need to drill new holes on the 300D to fit the trans mount from 240D closer to the engine?

The oil cooler is an additional radiator, correct? It's been a while since i've looked at my 240 unfortunately.

engatwork · #8 12-25-2021, 06:08 AM

IIRC the bolt holes should be in place.

t walgamuth · #9 12-25-2021, 11:00 AM

If no holes exist you can drill them.

h3ffe · #10 12-25-2021, 11:23 AM

They are present.

ROLLGUY · #11 12-26-2021, 08:02 PM

With the donor and recipient being the same chassis, everything will bolt right in. You will need to keep the glow plug relay, accelerator linkage, driveshaft, trans crossmember, shift rod, differential, and speedometer/odometer section together when moving it to the other car. Everything is bolt in, with no modification needed. You can even use the turbo radiator and expansion tank. If the 240 oil cooler has both lines going in the bottom, you will need to use it, regardless which radiator you use.

BradenFinney · #12 12-27-2021, 08:26 PM

Thanks for the comments on the trans support bolt holes! Good to know!

Quote:

Originally Posted by ROLLGUY

With the donor and recipient being the same chassis, everything will bolt right in. You will need to keep the glow plug relay, accelerator linkage, driveshaft, trans crossmember, shift rod, differential, and speedometer/odometer section together when moving it to the other car. Everything is bolt in, with no modification needed. You can even use the turbo radiator and expansion tank. If the 240 oil cooler has both lines going in the bottom, you will need to use it, regardless which radiator you use.

Wonderful summary, thanks for this info. I think my glow plug relay died. I will have to take a look at the car soon and get a summary of what I would need to replace for the transplant to work. Glad to know the turbo rad and expansion tank will cross over; my rad died in the wreck.

Here's hoping the seller can find a valid title so I can get to work on this project!

Phil_F_NM · #13 12-27-2021, 08:35 PM

In the swap you're probably going to have to swap the differential as the manual and automatic transmission cars have different ratios.
Could the donor car not just have the engine rebuilt? Seems like an easier job.

Phil Forrest

BradenFinney · #14 12-27-2021, 08:57 PM

Quote:

Originally Posted by Phil_F_NM

In the swap you're probably going to have to swap the differential as the manual and automatic transmission cars have different ratios.
Could the donor car not just have the engine rebuilt? Seems like an easier job.

Phil Forrest

I was anticipating the worst case scenario. As far as the differential goes, I've got an auto 240 and the new one is an auto 300. So even as those go there will be different ratios (presumably, won't know till I look).

With the new donor car, I absolutely will spend some time trying to evaluate the engine. The extent of my knowledge was that it had compression (320ish psi?). The owner then let the cylinders soak in WD40 to try and free up presumably stuck piston rings and gain compression. When trying to crank over after letting them sit for a bit, he got 0 compression... I will have to try and chase this all up myself and see what's up. I believe he replaced the timing tensioner spring and did not adjust valves yet. So I'm hoping for something easy like poor valve adjustment or timing marks out of time. If the donor car engine is anything too much, I would rather let the spirit of my 240D live on in another body. If I can fix the 300engine, I guess I'll need to find another donor body/front end for the 240, lol!

ROLLGUY · #15 12-27-2021, 11:14 PM

Quote:

Originally Posted by BradenFinney

I was anticipating the worst case scenario. As far as the differential goes, I've got an auto 240 and the new one is an auto 300. So even as those go there will be different ratios (presumably, won't know till I look).

With the new donor car, I absolutely will spend some time trying to evaluate the engine. The extent of my knowledge was that it had compression (320ish psi?). The owner then let the cylinders soak in WD40 to try and free up presumably stuck piston rings and gain compression. When trying to crank over after letting them sit for a bit, he got 0 compression... I will have to try and chase this all up myself and see what's up. I believe he replaced the timing tensioner spring and did not adjust valves yet. So I'm hoping for something easy like poor valve adjustment or timing marks out of time. If the donor car engine is anything too much, I would rather let the spirit of my 240D live on in another body. If I can fix the 300engine, I guess I'll need to find another donor body/front end for the 240, lol!

Definitely adjust the valves first. The exhaust valves tend to tighten (less clearance) with miles. I can't count how many times I have come across these with a "no start" condition, and all that was needed was the valves adjusted.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode