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Engine weights/Choices for W126 Powerplant

8069 Views 6 Replies 4 Participants Last post by  DAW
I searched and didn't really see much on this.......I have a 1980 Euro 280SE with an M110 K-Jet that had been sitting for a long time..I started it and it sounds grim..I suspect stuck valve vs piston top, knocks like it, compression is way low in one cyl so I have to tear into that engine (positives are high compression Euro engine and good cams), I have a spare USA market M110 (low compression pistons, US spec cams; but donor valves if I need them); I also have a spare Euro M110 head and intake manifold.

In moving the spare M110 it came to my attention that this engine is HEAVY! For a measly 2.8L this thing is a boat anchor! I love the DOHC and Euro specs, but..............and here's the rub...........
I have an excellent M103 3.0L SOHC complete running engine/trans from an '89 300SEL W126 that I can transplant; and I have an all-aluminum 3.2 SOHC V6 I can use. Assuming the M103 is a bolt-in and the 3.2L would be more time-consuming to adapt, which engine makes more sense ?:
M110 Euro-spec reincarnated from my spare pieces?,
M103 US-spec alive and running, low miles?, or,
3.2 alloy block/heads V6 transplant?.......

I'm leaning toward the M103 but I haven't pulled it yet from the donor car and don't know how its weight compares to the leaden M110 (the 3.2L is a featherweight; has to be far lighter than either I-6)..........input??
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Weight of M110 engine vs weight of M103 engine?
Thanks Flavio,
I think I'm going to transfer the M103 engine/trans complete assembly into my 280SE Euro. I just hauled a complete spare M110 USA 280S engine to the local scrap yard and dropped it off. I would not have used that low-compression engine in my 280SE unless I were to turbocharge it but it was one source for spare parts for my Euro M110 engine (valves, crank, rods, oil system, etc)......It weighed a lot! I guess I don't need the actual weights. The M103 is not likely any heavier than the M110.

The M103 is basically two cylinders longer than the 2.3 SOHC 4 cyl which I have in my '82 Euro 230CE (W123) and even though the M103 is a USA spec engine, it will be fine for my '80 Euro 280SE. The high-compression DOHC I6 with Euro-spec cams version M110 just had appeal to me and I can live with K-jet f.i. (it works fine in my 230CE). But between the weight issue and the money and time to refresh the M110...I guess I'm going to transplant the M103.

The 3.2 V6 I refered to is an MB engine and I will use it in one of my projects eventually and it is relatively light. My wife and I picked it up by the exhaust manifolds and moved it a couple of would take the whole family to do that with an M110.

Thanks for the useful input.
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