W123 300CD OM603 swap. The Sketchy Coupe *Now with more OM606!*
W123 300CD OM603 swap. The Sketchy Coupe *Now with more OM606!*
Here it is after towing it to our shop.
![[Image: pL3Newd.jpg?1]](https://i.imgur.com/pL3Newd.jpg?1)
![[Image: D6b6BqR.jpg?1]](https://i.imgur.com/D6b6BqR.jpg?1)
![[Image: Dalts9w.jpg?1]](https://i.imgur.com/Dalts9w.jpg?1)
I first wanted to make sure this was even worth attempting so I ran a ratchet strap across the engine sitting in the bay, rigged up a starter solenoid glow relay, hook up fuel lines, a battery, and hit the starter with some power. Much to the surprise of everyone at the shop, it ran. And it ran pretty damn good. Project Sketchy Coupe is a go.
Progress is constantly sporadic and brief, but I try to have something in the pipeline on this car. After making sure the 603 ran I turn my attention to how to mount the damn thing in the engine bay. I did a little bit of research, and found out my 603 was out of a w126. I decided to attempt to mount the engine using the 126 mounts and spacers. I made spacers out of 3/8" steel plate.
I could only push it so far, and my boys were of no help at all. luckily my brother lives pretty close and came to the rescue.
![[Image: QvAhbPD.jpg?1]](https://i.imgur.com/QvAhbPD.jpg?1)
![[Image: nlMZaxn.jpg?1]](https://i.imgur.com/nlMZaxn.jpg?1)
3/8" spacer, and I also overbuilt a trans crossmember out of 3/8" as well.
![[Image: Ez5JhF9.jpg?1]](https://i.imgur.com/Ez5JhF9.jpg?1)
![[Image: ebKW0Ai.jpg?1]](https://i.imgur.com/ebKW0Ai.jpg?1)
Time to throw the engine in.
![[Image: 4sVNTgm.jpg?1]](https://i.imgur.com/4sVNTgm.jpg?1)
![[Image: 5a0R0iy.jpg?1]](https://i.imgur.com/5a0R0iy.jpg?1)
it pretty much lined up on the first try using w126 om603 arms and mounts with my spacers.
Cap had hacked the radiator top mount/support out in order to shove the engine in to the bay of the sketchy coupe. From what I understand he did this in order to avoid a fine from the city for have an "abandoned vehicle" on his property. This made it a real pain in the ass for me, as the frame rails ended up collapsing in by about 1/2" or so. I was using a 124 603 radiator I pulled out of the junkyard and it wouldn't fit. Rigging up a bottle jack and spreading the rails until my top mount fit again did the trick and I tacked it in place, threw the radiator in, began hacking up radiator hoses until it fit. I'm pretty unhappy with the expansion tank and how that hose is ran. It'll work for now and I was able to bleed it, miraculously.
somewhere in there I did an A/C delete, and the battery was relocated to where the back seat was.
![[Image: vdXEFLT.jpg?1]](https://i.imgur.com/vdXEFLT.jpg?1)
![[Image: kuwOiRS.jpg?1]](https://i.imgur.com/kuwOiRS.jpg?1)
![[Image: 9udzN4Q.jpg?1]](https://i.imgur.com/9udzN4Q.jpg?1)
Bungie corded the grille on for test driving purposes.
I attempted to swap the 126 tach into the 123 cluster in order to have a factory tach.
![[Image: JKu8FXc.jpg?1]](https://i.imgur.com/JKu8FXc.jpg?1)
![[Image: H5rPHpo.jpg?1]](https://i.imgur.com/H5rPHpo.jpg?1)
![[Image: 5ffil0k.jpg?1]](https://i.imgur.com/5ffil0k.jpg?1)
![[Image: ZfZvdI5.jpg?1]](https://i.imgur.com/ZfZvdI5.jpg?1)
This ultimately did not work. the 124 crank signal runs through a few other components that I did not have. I had to figure out another way to get a tach without breaking the bank.
Somewhere along the way I decided to rip out the disgusting interior, and everything behind the dash. Weight reduction bro!
I removed the ALDA, and turned up the pump a couple turns. I also rigged up a w124 om603 throttle cable to the w123 pedal. I ordered some ebay hood pins so I could throw the hood back on. I also cut a big hole in the hood for the exhaust. I drilled a hole at the bottom of the 90° to drain rain and such.
![[Image: TlgRKxr.jpg?1]](https://i.imgur.com/TlgRKxr.jpg?1)
![[Image: 8gM3pqT.jpg?1]](https://i.imgur.com/8gM3pqT.jpg?1)
I wanted to make sure I wasn't melting pistons so I turned to ebay and bought some super reliable chinese gauges. I ordered boost, egt, an a digital frequency counter to attempt to make a tach.
Boost gauge was very easy to setup. After ordering some adapter fitting I was able to install the egt probe into the factory manifold as well. Here I am testing them out:
They work! I can't imagine that egt gauge is incredibly accurate, but hopefully it'll keep me from doing serious damage.
I turned my attention to the frequency counter. I wired it up to a 5V power supply, grounded the ckp, and ran the signal wire to the frequency input pin of the counter. Had to change a few settings around on the counter and it worked! not bad for 8$!
That's pretty much all my progress for the time being. I really need to throw tires, tie rod, clean up wiring, and a battery tie down before I do much else. The plan is welded lower ratio differential, hydro handbrake for skids, and more weight reduction to increase the fun of the car. If I had a higher budget I'd love to do a 5spd swap (we have a few E36 ZF 5 speeds laying around), Turbo, and reworked injection pump. I can't imagine this cylinder head can handle too much more abuse though.
![[Image: 4bdHEeJ.jpg?1]](https://i.imgur.com/4bdHEeJ.jpg?1)
Granfatherglock
04-19-2018, 07:32 AM #1Figured I'd introduce myself and my project through this build thread. I'm a Mercedes tech at an indy in Richmond, VA. My younger brothers neighbor was paying someone to tow away his '85 W123 wagon and '83 W123 coupe. He ended up giving them both to me. The Wagon is a whole 'nother story. The Coupe had an OM603 with matching trans sitting in it. It also had the cut springs, factory 16x7 BBS wheels, Zender front bumper, euro rear bumper, and urban camo? hand painted paint job on it when it came under my ownership. I focused on the wagon first and was able to get it running after a lot of work, I now daily drive the wagon. After a while I turned my attention to the Coupe. The previous owner (we'll call him Cap) informed me the engine was in unknown condition and the car was severely rusted, Cap had already replaced the driver side floor pan. My goal here is to build a somewhat enjoyable car for little to no money, as this is a fifth car for me and the condition of the car is, at this point, sub-par at best. Just to be clear, I know this build isn't most peoples taste, but it isn't mine either. We're just working with what we've got!
Here it is after towing it to our shop.
I first wanted to make sure this was even worth attempting so I ran a ratchet strap across the engine sitting in the bay, rigged up a starter solenoid glow relay, hook up fuel lines, a battery, and hit the starter with some power. Much to the surprise of everyone at the shop, it ran. And it ran pretty damn good. Project Sketchy Coupe is a go.
Progress is constantly sporadic and brief, but I try to have something in the pipeline on this car. After making sure the 603 ran I turn my attention to how to mount the damn thing in the engine bay. I did a little bit of research, and found out my 603 was out of a w126. I decided to attempt to mount the engine using the 126 mounts and spacers. I made spacers out of 3/8" steel plate.
I could only push it so far, and my boys were of no help at all. luckily my brother lives pretty close and came to the rescue.
3/8" spacer, and I also overbuilt a trans crossmember out of 3/8" as well.
Time to throw the engine in.
it pretty much lined up on the first try using w126 om603 arms and mounts with my spacers.
Cap had hacked the radiator top mount/support out in order to shove the engine in to the bay of the sketchy coupe. From what I understand he did this in order to avoid a fine from the city for have an "abandoned vehicle" on his property. This made it a real pain in the ass for me, as the frame rails ended up collapsing in by about 1/2" or so. I was using a 124 603 radiator I pulled out of the junkyard and it wouldn't fit. Rigging up a bottle jack and spreading the rails until my top mount fit again did the trick and I tacked it in place, threw the radiator in, began hacking up radiator hoses until it fit. I'm pretty unhappy with the expansion tank and how that hose is ran. It'll work for now and I was able to bleed it, miraculously.
somewhere in there I did an A/C delete, and the battery was relocated to where the back seat was.
Bungie corded the grille on for test driving purposes.
I attempted to swap the 126 tach into the 123 cluster in order to have a factory tach.
This ultimately did not work. the 124 crank signal runs through a few other components that I did not have. I had to figure out another way to get a tach without breaking the bank.
Somewhere along the way I decided to rip out the disgusting interior, and everything behind the dash. Weight reduction bro!
I removed the ALDA, and turned up the pump a couple turns. I also rigged up a w124 om603 throttle cable to the w123 pedal. I ordered some ebay hood pins so I could throw the hood back on. I also cut a big hole in the hood for the exhaust. I drilled a hole at the bottom of the 90° to drain rain and such.
I wanted to make sure I wasn't melting pistons so I turned to ebay and bought some super reliable chinese gauges. I ordered boost, egt, an a digital frequency counter to attempt to make a tach.
Boost gauge was very easy to setup. After ordering some adapter fitting I was able to install the egt probe into the factory manifold as well. Here I am testing them out:
They work! I can't imagine that egt gauge is incredibly accurate, but hopefully it'll keep me from doing serious damage.
I turned my attention to the frequency counter. I wired it up to a 5V power supply, grounded the ckp, and ran the signal wire to the frequency input pin of the counter. Had to change a few settings around on the counter and it worked! not bad for 8$!
That's pretty much all my progress for the time being. I really need to throw tires, tie rod, clean up wiring, and a battery tie down before I do much else. The plan is welded lower ratio differential, hydro handbrake for skids, and more weight reduction to increase the fun of the car. If I had a higher budget I'd love to do a 5spd swap (we have a few E36 ZF 5 speeds laying around), Turbo, and reworked injection pump. I can't imagine this cylinder head can handle too much more abuse though.
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