Station wagon converting to diesel - PeachParts Mercedes-Benz Forum

1987_300td · #1 02-06-2013, 12:22 AM

I bought a station wagon, 1990 TE gasoline with overheated engine. I have a 1987 diesel that I could use the engine from and install into the 1990 wagon. I would like to see what things I might run into, i.e. fuel tank same or needs replaced; wiring; computers; registration at DMV and so on. I really like the station wagon and would like to make it my primary. Thank you in advance!!!

vstech · #2 02-06-2013, 12:59 AM

fuel tanks are not the same. it may be possible to convert it over though. I have both, and am considering pulling everything and setting side by side. the gasser has two fuel pumps and filters under the car, the diesel has the two fuel lines for supply and return it may be possible to swap parts between the gasser and the sedan diesel tank to make it all work... not sure, the tank screens are different between gasser and diesel wagons, and diesel sedans... all 3 different...
SLS system should bolt up to the sedan engine, I'd pull the ignition switch and swap it to the wagon... then the issue of the klima system, the idle system, etc... you may be able to swap all that from the sedan as well... swap the speedo and rear diff, or you'll have sub 20mpg in the diesel. ...

Woody Worker · #3 02-06-2013, 01:30 AM

First order of business is to determine whether you can legally swap a diesel engine into the gasoline power chassis, each state has specific rules and criteria, check that you can meet them before you you do much else. Probably won't ever meet emissions with a diesel drivetrain and a gasser VIN if your state requires inspections.

After that hurdle is overcome it should be doable and pretty straight forward.

Assuming the 87 diesel is a sedan most of the engine bay and drivetrain parts will be pretty straight forward. Most of the mechanical pieces and parts are nominally swappable, the fuel system will require some investigation if you are swapping fron a sedan to a wagon.

The one area that can be problematic is the electrical system with regard to the engine compartment mainly, but fortunately with the 124 chassis even that is pretty modular in design and implimentation so you very well may be able to unplug the wiring loom say from the engine compartment in the diesel sedan and use that to plug and play right into the back side of the fuse box/electrical distribution system in you wagon. You might need to swap out the engine wiring loom and the engine's electronic control wiring loom that runs across the front between the the firewalls. This is something you will need to plan around because obviously the best time to accomplish that would be when the engine bay is empty and you can gain easier access to the firewall areas. All the interior wiring for the ACC, lighting, seats, windows, exterior lights should probably not need screwing with. Wiring to the instrument cluster wil be a bit different but that might be a simple as one connector at the back of the fuse box or it could be tied into the engine compartment wiring. Stuff like the SRS will should be independent and be left in place pretty much.

GregMN · #4 02-06-2013, 11:10 AM

From my experience with a W201 swapping a 2.6 gasser for a 2.4 diesel:

Day 1: Remove engine and transmission from donor car.
Day 2: Remove engine and transmission from gas car. Leave the A/C compressor and P/S pump systems hooked up and in the car. Label all wires as they are disconnected from the engine before removal. Have the fuel pump empty the gas out of the tank for you before you disconnect it.
Day 3: Decide what items will be going back into the gas car. Make those swaps.
Remove and bypass the gas fuel pumps.
Which transmission?
Which radiator?
Which exhaust system?
Which Alternator?
Which motor mounts?
Day 4: Install engine and transmission in car. Start it up, drive it away by the end of the day.
Now you can drive it while you attend to getting all the little issues fixed.
I used two electrical vacuum control valves to handle the "shut down" and "run" on the IP. I found it to be easier than swapping the ignition switch.
The gas transmission worked just fine on my set up. I used it because the transmission on the donor was not good.

For all the wires that are "left over" from the gas engine: After you have everything working with the diesel engine, and you are sure you don't need them, cut them out and toss them.

Aquaticedge · #5 02-06-2013, 11:47 AM

It'd be incompatible I'm sure, but it'd be interesting to see a 4matic swap like this

DieselPaul · #6 02-06-2013, 12:02 PM

On a 4matic the oil pan is specific, so you'd need to build a custom oil pan or somehow adapt a 103 pan to a 603. Cool idea, but more work than its probably worth.

Aquaticedge · #7 02-06-2013, 12:20 PM

True, it would sure be interesting though, I'd love to drive one once. I'd love to drive a 4matic period, wonder if its any different then a standard type car

vstech · #8 02-06-2013, 12:30 PM

are you certain the 103 pan will not fit the 603?

GregMN · #9 02-06-2013, 06:42 PM

Quote:

Originally Posted by vstech

are you certain the 103 pan will not fit the 603?

I would be more surprised if it didn't than if it did.

103 sump holds 6.5 liters (no side tank)
603 sump holds 7.5 liters

The oil pans look exactly the same where they mate with the block in the FSM.
The gaskets look almost the same.

duxthe1 · #10 02-06-2013, 07:55 PM

The gasket is the same between the 103 and 603 (and 104 and 606), but the 4-matic pan is glued on without a gasket. In some markets the 603 was offered with the 4-matic, you can find it if you dig through WIS. I've always wanted to build a 606 turbo 4-matic wagon. Had to settle for a turbo 103 though.

1987_300td · #11 02-06-2013, 11:23 PM

Today, I took the engine out of the st wagon. I separated the transmission, the torque converter is blue...does it mean it was rebuilt? Are they interchangeable with diesel?

Does leveling suspension need to be removed or it is compatible with OM603?

vstech · #12 02-07-2013, 07:21 AM

I'd guess it's been replaced, also, the TC bolts are hex, not spline, but i've never had a 603 trans out before... they may all be hex.
either way, the suspension pump will bolt up in place of the 603's power steering pump.

GregMN · #13 02-07-2013, 09:48 AM

If the diesel engine and transmission are the same length as the gasser then I wouldn't even separate them, I would just install them as a unit. If they are a different length, then I would bring over the driveshaft from the diesel too.
The total length of the drive train ( motor mount to diff.) should be the same in all W124's.

The TC bolts in my 601 and 603's were spline head.

hudson6 · #14 02-07-2013, 11:09 AM

I have a similar project go also
and here is what I know
1 bought the oil pan from Germany, the gas pan/rear is to short by say 1"
was going to cut and re weld but found the right one.
2 the oil pump is different, the gas bolts in but the sprocket is off
so I put the rear half of the gas pump on the diesel pump and welded in the mismatch areas and sanded the mating surfaces smooth,
the oil pump you need is 6301802101 it's about 500 to 600 to get it from Europe.
3 the tach pick up is different causing a problem with the air conditioning system and tach indication, one is DC the other is AC one picks up 3 tabs on fly wheel the other on the ring gear. So we are making a puck up on the front for the gas pick up 3 tabs.
4 key for the vacuum shut off is just adding parts.
5 glow plugs not hard need to add power wire ect use ignition power to run system
6 motor mounts off gas bolt on 603 and all bolts back in car with original trans and torque converter.
7 engine wires, no electronics just base Idle
re use wires out of original harness for temps and pressure
8 you need to use the diesel radiator for correct hose hookups it bolts in, and don't forget the oil cooler.
The turbo diesel 4 matic in Europe is a 124.333 engine is 603.963
non turbo engine 603.913.
having fun now

1987_300td · #15 03-28-2013, 07:40 PM

My project froze due to donor engine being bad. I am in process of rebuilding it. Engine has approx 250k mi, stock cylinder wall (see pic). What size of rings do I need? Do I need to use brush for honing or can I just install them?