M103 transplant/swap
 

I recently bought a wrecked '92 300E for its transmission, exhaust and some interior parts, to go into my '91 300E, but I've decided to bring the engine over also .. since it has less miles and seems to be in better condition than the legacy. I'm preparing the donor car 1st to limit the downtime.

I've removed the exhaust, disconnected everything off the trans, vac/fuel lines etc., then I moved over to the "brains" area next to the battery where all the MAS, ECU, OVP wiring is.

My question is this: what wiring on the 124 goes with the engine and what stays? The MAS, ECU and other computer's wiring all conjoin (see pic) and then branch off to different areas. Only one wiring harness emerges out of the firewall and enters the railing across the engine. I would think that is the one I want to take with the swap but since that bundle mates with others that lead to various chassis areas I can't separate it from the bunch.

Hopefully I don't have to cut and splice!!

Anyone who's ever done this job and/or could provide some insight would be very much appreciated. :D



http://pauls-space.zftp.com/ECU harness.jpg

http://pauls-space.zftp.com/ECU harness_2.jpg

i dont understand
 

are you going to put the engine in subaru?

tom w

It's going into a '91 300E.

It's the same engine and electrics. What's the question?

The question is: is it easier to just leave engine wiring behind on junker chassis or take the harness with the engine?

I know most of the electrical connections that run down the wire railing are to easily accessible sensors but I recall seeing a couple run down beneath the intake that look like they'd be tough to get to.

Also I failed to mention the fact that the transplant engine is from a CA car and has an extra sensor in the wiring loop -- an air temp sensor that attaches to the air filter hose that when not connected trips the check engine light. My Fed. 103 doesn't have this sensor.

Thanks for the reply.

i have no
 

specific knowledge of that car, but as yogi berra used to say "you can tell a lot just by looking". i would just look at stuff, trace wires and seek connectors. if it is best to leave wiring on the engine i bet you will find a connection that will allow it to be unplugged when you pull the motor out. then just unplug things carefully and try not to damage old brittle wires as much as possible.

good luck.

tom w

Leave the harness alone. Swap parts from the '91 as needed to hook up the '92. No matter if there's a sensor on the '92 that isn't on the '91. If you use the electronics from the '91, it'll never know that the air temp sensor isn't connected, because it won't be looking for one.