om603 to w124 swap

[ashedd]

I know this is opening up a can of worms... but here we go.

What if I wanted to do something really dumb, like swap my om603 into my '90 300TE?

I have ZERO concern about the legal logistics. I am more concerned about mechanical/electrical differences.

The actual engine/transmission swap in pretty straight forward. But as we know, the 603 has some electronically controlled systems.

Emissions crap? Don't worry about. I have removed all that anyway. Even the "flapper" thingy under the air box. My concern is OVP and idle control. I would VERY much like to be able to get the a/c compressor to work properly after the swap. I know some of that stuff is located in the right foot/kick panel on the 603 w124, the '90 TE doesn't even have the access panel in that position. I must assume nothing is behind that panel in the TE.

Then we have the "stuff" that lives behind the batt. On the TE there look's to be a "computer" of sorts. The 300d has little to nothing back there. There is also the glow circuit. I think that is pretty straight forward, just move the relay and associated wiring to the TE.

Speedo/cluster swap(easy). Fuel tank.. probably get away with using gas fuel tank.

Let's see...
Transmission/rear diff. As you can see from my signature, I have a 5 spd 300d. I do still have the auto tranny in the garage. However, the 2.65 diff in my 300d is BAD. So if I want to go om603/automatic in the TE... I NEED to find a new 2.65 rear diff, easier said than done. Jeff had one but I think it's gone now.

On the flip side: I could put the 5 spd in the TE. Some would LOVE that combination, I am not so sure though. The thought of a 5 spd wagon does not really appeal to me. BUT, I would not need to find a 2.65 rear diff. AND more than likely, the gas TE diff will be more suited for the 5 spd. See my diesel performance thread about my 5 spd swap to see why the 2.65 is too tall for a 5 spd.

So why not just buy an '87 TD? Welllll, I have yet to see a 100% rust free, nearly mint '87 TD that was less that $6-7K, Even IF I found one, I would have to swap the newer body moldings, interior trim, power window "convenience" option, etc.

My TE is 100% rust free and nearly mint. The m103 is silky smooth BUT I hate the MPG's. The 103 runs really warm(all related parts have been replaced) and starts in 2nd gear. That 2nd gear start kinda sucks with the a/c on.... lot's of "flooring" it to get it to move. Plus my fuel pumps are kinda loud.. I would hate to have to buy new ones.

Let's talk 300d. The one I have is mostly rust free(jack points), runs GREAT. But does need new interior parts, fender has a big dent from storm damage, paint is so so.

If I had a 603 powered 124 wagon, I would be very happy. I would, however, like to have another 400e/e420(m119) as a second car. The only concession to the V8.. M104 powered 124 sedan, and I would use my OTHER 5 spd stuff and swap it.

So what do you think?

[Jeremy5848]

There isn't anything behind the passenger right-side kick panel in a W124 -- you're thinking of the 1985 W123 diesel. Behind the battery, a W124 diesel has the EGR brain, which controls the electronic idle (and the tach signal passes through it), the OVP relay, an altitude sensor that talks to the EGR brain, the ABS brain, and the Klima relay for the air conditioning.

I suspect the ABS brains may be the same but the EGR brain is different. You could get along without the electronic idle control if you really have to but it's nice to have. You would have to get that part of the wiring harness out of the car that donated the 603 engine. The OVP relay may or may not be different; the Klima relay definitely is different from gas to diesel.

If I were to undertake such a project, I would want a complete (more or less) W124/OM603 donor car so that I could make comparisons and move parts as I found them to be necessary. There are lots of little "gotcha" items, I bet.

Jeremy

[ashedd]

Originally Posted by Jeremy5848

There isn't anything behind the passenger right-side kick panel in a W124 -- you're thinking of the 1985 W123 diesel.

haha... sometimes I feel pretty silly.

Good thing I have a complete donor car

Dunno what in the heck I would do with the m103 and transmission. Guess I could sell it easy enough

[sixto]

Originally Posted by Jeremy5848

There isn't anything behind the passenger right-side kick panel in a W124

Isn't the airbag module in that area?

Sixto
87 300D

[Jeremy5848]

Originally Posted by sixto

Isn't the airbag module in that area?

Sixto
87 300D

The airbag electronics are divided among three locations. The (explosive) "squib" and the airbag itself are, of course, in the steering wheel center. The sensor (accelerometer) is on the transmission tunnel ahead of the ashtray. The "energy accumulator" (just a big capacitor) and one other component are indeed behind the right front passenger kick panel. I had forgotten that so thanks for catching my error. At least there's nothing that needs to be moved for an engine swap.

Jeremy

[ashedd]

ok, and the alarm module is under the "foot" area of the pass side? Seems like there is something else living next to the alarm..

I have yet to study the wiring diagrams.

[ashedd]

ah yes! How could I forget the SLS!

Any idea if the 603 has a "wagon" head and sedan head?

[compu_85]

Nope, they're the same, the SLS was handled by the power steering tandem pump. I just gave one to WHunter, I bet he'd sell it to you for a good price!

-J

[Jeremy5848]

Yes, SLS is a bolt-on option. It may even have been installed in the odd sedan. BTW, try to get a late-casting head to install on the 603 while you have it out (if it doesn't already have at least a #17 casting). I believe Mercedes went up to #22 before they quit tweaking.

[compu_85]

Actually, I think the 3l gas motor used the tandem pump as well. Look at how many lines are running to it. Tandem pumps have 4?, regular power steering only is only 2 I think?

[ashedd]

ok, I will look at the PS pump today. I REALLY need to purge all this w123 crap from my head. Anybody want my '85?? Sick of staring at it.

I would like to get a later casting head someday. Dunno if I want to pay 700-800 bucks for a preventative maintenance item. But if my 14 head ever cracked... that would suck.

[ashedd]

My 300d has a two line PS pump. I wonder if the PS pump from the 103 would fit the 603?

How many systems are shared between a gas w124 and diesel?

I was looking at my IP and it's fuel line connections... will the 103 TE have the same feed/return lines attached to the left wheel well? Kinda hard to look without pulling parts off the 103.

Then I look behind the batt on my 300d. I notice the Klima and the term "kickdown" written on it. Got me thinking: will the TE have the same kickdown wiring? I know I am going to have to study the schematics for each car, but I just wonder how much different is the harness.

Can of worms, can of worms.

If I had say, a '95 TE with a bad harness/blown headgasket... the swap would be in progress already.

[Aquaticedge]

Originally Posted by ashedd

Anybody want my '85?? Sick of staring at it.

If it's a crapper one Ie parts. I'd be interested in it for the motor and trans.

[ashedd]

Originally Posted by Aquaticedge

If it's a crapper one Ie parts. I'd be interested in it for the motor and trans.

I dont think it's a parts car just yet. It does have alot of new parts, and some rust. But it does clean up nice. Currently it's still getting air in the supply hard line somewhere. I have not fooled with it in a couple months.

[ashedd]

same PS pump, according to auto house.