Vanidia

Hi all, I'm a new member but have been browsing for a couple years and now need a little help.

Like the title says I have a 93 and 95 w124 with the m104. My 93 is a beautiful low km jap import but unfortunately the harness was never replaced and have been reaping the excitement that comes with all that and I believe it's never had gaskets done as it's leaking from the head and oil pan and unfortunately it's not a very well kept example. The ETA is also playing up so it's been parked up in a garage. About 6 months ago I bought this 95 E320 as it was owned by a wealthy man who had the wiring harness done by Mercedes and kept the motor in a lot better condition, I bought it for a bargain as there is some serious rust issues but could drive it until the next warrant of fitness comes up. Unfortunately the 95 320 was broken into and had the ignition barrel busted up as some fools thought they could steal her and now I need to make a complete working car out the two.

I have been enquiring around a few local shops and have had some bites but there's a lot of head scratching going on their end and I need some help clarifying the complexity of the job. From my understanding the 93 320E has the M104.992 and the 95 E320 has the M104.995, from my research I understand the .995 has fly by wire throttle instead of the ball join mechanism and no idler gear for the timing chain + some material changes for the chain guides?

My plan is to swap the entire motor, wiring harness and ECU (potentially the tcu too) from the 95 into the 93 but is it that simple? Are there any changes from the cabin harness to the ECU or any other component changes/upgrades I need to be aware of? Is the 4spd auto the same box? Bit of a pickle as my good car is the weird model year where is should have a m103 but I believe the story is they ran out of m103s at some point in 1993 and the m104s were used.

Any help will be hugely appreciated

dolucasi

You never mentioned the mileage on these engines. Also the '93 is electronic injection as well? Not the KE-Jetronic?

Vanidia

Well the 93 has about 115km and the 95 is about 240km. But yes the 93 has motronic system. They're essentially the same motor. I've talked to one shop and they say they can do a hard motor swap but can't use the harness and ECU which confuses me because I can't imagine why not? The ECU doesn't have some ridiculous security system where you need some harness from the cabin or even the gauge clusters? It's too old for that right?

dolucasi

Wire harnesses from one year may not match the harness for another. Especially in your case where one car is a transition year engine.

An engine that only has 115K km is the one to keep not the 240K km one. I would just fix the leaking gaskets and move on. Also just replace the harness on the '93.
Looks like you maybe able to use the '95 harness you already have if you truly believe they are the same with the '93. Check the part numbers of both years for the harness.

A leaking head gasket is standard on M104 it seems. My '95 was replaced by MB many moons ago. Dealership claimed it is not covered under warranty. They eventually covered it. Unfortunately is it a lot of work. Make sure it is the head gasket and not something else.

Also at 240K Km mileage, you do not know when the HG will start leaking again. Like 6 months after you transplant it. Mine at least went another 150K Km after it was replaced at 75K km, but I sold the car for a failing transmission at 220K Km.

My 2 cents worth.

Vanidia

Hi cheers for the reply.
This is my main concern that the harness won't work but I just can't imagine what would be different if they're the same essential motor? I will see whether the part numbers are the same thanks. Maybe I am too keen to swap the motors (even if the high km one runs really well no blow by etc) and maybe I should just tackle the gaskets and transfer the cooling system and eta and the harness... I am trying to not spend everything I have hence why I thought a complete engine and harness swap would be the most effective but I'll have to enquire about keeping the motor and doing a Frankenstein build perhaps.
Your 2 cents is much appreciated 👍

dolucasi

Just remember that the Achilles heel of the M104 era is the auto transmission. Your '93 should be fine. I would worry about the '95 if it is the original auto transmission.
Once the reverse gear goes, that is a big cost.

Hopefully you can refurbish that almost new '93 M104.