Engine Swap (purists look the other way) - PeachParts Mercedes-Benz Forum

indybenz · #1 02-16-2021, 01:36 PM

Feels like forever since I posted here.

I was in Indiana now I'm in Glasgow, Scotland.

I finally got my hands on a W123, a relatively clean 240d 4spd manual.

I've also got a W202 C250 Estate with the autobox attached to the OM605 (i5 turbo diesel).

I'm gonna put the 605 in the 123, keeping the electronic pump and using a controller from Iceland (Baldur).

I know it's been done a bunch of times, but the folks on the super turbo diesel page aren't active much.

I'm wondering if folks here have any suggestions regarding the transmission.

Will the 4speed be able to mate with the 605? Not in terms of power but in terms of actually fitting together.

Shall I keep the auto box mated to the 605 and make it fit, sourcing a driveshaft or having one made?

I can get a 5 speed manual conversion for the W202 for relatively cheap over here. Would that be a better choice?

I'm not going for burn outs here; 70 horsepower just isn't enough and the 605 has 150 without doing anything to it.

Just makes sense to me.

If it weren't for the steering wheel being on the wrong side I'd prefer a stock turbo 617 but alas that's not gonna happen.

Thanks!

Jon

vwnate1 · #2 02-18-2021, 11:49 PM

Looks like fun to me, I have no idea about your questions but will be watching as you do this .

dieselbenz1 · #3 02-28-2021, 12:22 PM

Will the 4speed be able to mate with the 605? Not in terms of power but in terms of actually fitting together

Pretty certain the starters are on different sides.

indybenz · #4 02-12-2022, 08:32 AM

Quote:

Originally Posted by vwnate1

Looks like fun to me, I have no idea about your questions but will be watching as you do this .

Hey sorry I missed this! Thanks for the warm welcome back :-) I'm moving back from Scotland to the US later this year and will be bringing this with me...after I figure out what the hell I'm doing

indybenz · #5 02-12-2022, 08:40 AM

Quote:

Originally Posted by dieselbenz1

Will the 4speed be able to mate with the 605? Not in terms of power but in terms of actually fitting together

Pretty certain the starters are on different sides.

Thanks for asking and sorry I missed this reply.

I've got more updates on Benzworld...but nobody is really active on my posts other than me. Guess it's not exciting enough or something.

I've gone with a 5 speed manual (717.413) from a W124 with the 5 cylinder OM602, which shares the same bolt pattern and starter location. So all should be ok there.

I've also decided to upgrade the fuel pump and go mechanical. 7.7mm element job from DPUK. Quite expensive but should be good.

I've got the 605 out and on a stand.

240D still in the 123 and just waiting/prepping for a space inside my garage to really sink my teeth into this.

Trying to sell the om616 and manual 4 speed but absolutely no takers or even tire kickers over here.

My current research is about getting a tachometer going in the 123. It has no tach. I've spent hours and hours researching but still wondering which way to go.

More on that in the next installment!

indybenz · #6 02-12-2022, 09:41 AM

I have the donor car (1998 C250 5g tronic) so have access to all the parts.

I was thinking of keeping the "cam position sensor" which feeds the tachometer (PN A0031537426) and rather than trying to get an MB tach (too much work!) just getting an inexpensive digital one. They're like £10-15.

Sensor images attached.

Cheap tachs attached as well.

Would this work?!

vwnate1 · #7 02-12-2022, 11:23 AM

" ...after I figure out what the hell I'm doing"

Uh, I hate to tell you but I don't know if that's always possible, just pick up your wrenches and keep muddling along please .

I guess today's Scotsmen are not as thrifty (cheap) as my ancestors were, they'd have jumped at the chance to grab a lifetime vehicle like a manual gearbox W123 240D

.

I'd stick with the factory TDC sensor as it makes a good RPM source .

I'm using a tiny tachometer like you show as a portable tune up tool , they're great .

I can't believe you're unable to find a cheap (under $100) decent looking tachometer, I've collected what I *think* (& hope !) are all the parts to add a factory VDO tachometer and clock to my 1982 240D ....

It's fun chasing the details, I don't really care what others think of how my vehicles are built, I'm a huge fan of the 'mix 'n match' philosophy .

indybenz · #8 02-12-2022, 12:45 PM

Quote:

Originally Posted by vwnate1

" ...after I figure out what the hell I'm doing"

Uh, I hate to tell you but I don't know if that's always possible, just pick up your wrenches and keep muddling along please .

Yeah man no choice now. I've spent too much money and time and this time (unlike many other times) I'm not going to walk away!

Quote:

I'd stick with the factory TDC sensor as it makes a good RPM source .

I just need to figure out how to get it to work with my new set up.

Quote:

I'm using a tiny tachometer like you show as a portable tune up tool , they're great . I can't believe you're unable to find a cheap (under $100) decent looking tachometer, I've collected what I *think* (& hope !) are all the parts to add a factory VDO tachometer and clock to my 1982 240D ....

VDO is my first choice. Something that 'matches', but it's getting it to work that is my hangup. I've spend HOURS AND HOURS trying to figure it out and it's just one tiny part of my entire swap...so it's a bit of a drag on my energies and motivation at the moment. How does your wee one work, as in where do you hook it up??? That's really all I want to know!!!

Quote:

It's fun chasing the details, I don't really care what others think of how my vehicles are built, I'm a huge fan of the 'mix 'n match' philosophy .

I'm with you. I like the mix n match myself. Makes the vehicle feel more like 'mine'.

Scrappy · #9 03-18-2022, 11:36 AM

indybenz,

Any chance you can toss a couple spare 717.413 in your suitcase on your way

back to the US?

For us lowly worms that are stuck with four speeds here in the wild west...

indybenz · #10 04-13-2022, 03:10 AM

Quote:

Originally Posted by Scrappy

indybenz,

Any chance you can toss a couple spare 717.413 in your suitcase on your way

back to the US?

For us lowly worms that are stuck with four speeds here in the wild west...

Not sure the best way to ship those, but I'd definitely help folks out if someone coached me through the process. Happy to help!

indybenz · #11 04-13-2022, 03:13 AM

I've gone with a tachometer from an OM602 powered W124. We'll see how that goes once I get to it. Have some help from a Moscow-based diesel Benz enthusiast to get it wired in properly.

My next issue/question is what to do about the glow plug relay, swapping it over from the donor car and modifying it to work in the W123. The donor car had the EDC pump and lots of electrical thingy stuffs, whereas the old 240 is mostly mechanical. I know the OM605 prefers an 'afterglow' type set up, where the glowplugs stay on longer past the startup...no idea how to make that happen with a mechanical set up.

Anyone have a suggestion?

indybenz · #12 04-13-2022, 05:23 AM

I've checked and the relay is definitely different. The more 'modern' one is more like an ECU. I have located a used relay and harness from an OM602 and am wondering if I should go with that instead of trying to make this work.

Part number for the relay from the donor car: PA66F30

PN for OM602 relay: A0055454032

Then the harness is also different in terms of how it connects to the relay, so I'd probably just get a replacement harness/loom to match the relay.

Happy for anyone to chime in if you have ideas about this.