Oportunity to get a m3 engine

[Dekoninck]

Hello there.

I am the happy owner of a 325i e36 and today I have met someone willing to sell me a m3 e46 engine with some issues that I am thinking of buying for a future swap when the 25 dies (hope in a looooong time away)

One of them is failure of the sixth piston. The guy says that he have a new one which would be given to me in case that I buy the engine. Nothing mentioned about the connecting rod issue known for this model but anyway, as I would tear the whole engine appart, I think that it would be nice to change the rods bearings just in case among other things.

He has also mentioned that the cylinder head is in good condition but, same here, I think that I would send it to be properly check and machined (if needed). The sixth cylinder probably would need to be machined (in the worst case) and I have no idea of how much it could cost.

The guy is a mechanic and has told me that he could rebuild the whole engine around the 2000€ or so and I think it's way too much considering the "few problems" that the engine is supposed to have. I could do the whole rebuild by myself but of course, I would need external help for machinery.

Nothing mentioned about the "common" vanos issue.

Said so and numbers in the table, he is asking for 1200€ for the engine excluding alternator, exhaust manifold and ECU and including a new piston to replace the broken one. I think it could be lowered a bit as he is willing to get it out of his home and I think (in my ignorance) it is a fair prize considering the prize of used m3 engines laying around (in Spain where most of the guys having an m3 are drug dealers without any love towards car culture more than revving and doing bournouts (respect for the rest of owners)) that, for sure, would need some work.

I am open to ANY kind of comments. If possible, would be happy to know how much do you think it would cost to have it running and what to look for if I decide to buy it. Of course, I don't think the guy would have any kind of problem of tearing it appart a bit to have it checked before buying it.

Thanks a lot and happy new year!

[MauiM3Mania]

Copied to General Mechanical sub-forum.

[bmwdirtracer]

Welcome to the forum.

Pistons don't just break. "Here's a spare piston" is not the answer If the piston broke, both the crankshaft and the cylinder block are highly suspect. In fact....if the sixth cylinder needs to be machined, then you need a whole set of pistons, and rings, and maybe ?
The last two M-engine rebuilds I did were $15,000 and $13,000 respectively, with the owners buying most of their own parts far less than retail. How many miles on this motor? Don't forget to add upper and lower gasket set. set of pistons, set of rings, a couple thousand dollars in machine work and balancing, main and conrod bearings, valve job, valve adjustment, timing tools, valve adjustment tools, timing rails, cam bolts.......and on and on.

Caveat emptor.

[ross1]

So let me get this right. You are contemplating buying a probably very badly broken engine to have as a spare for one that is currently doing fine. Correct?
I guarantee you'll need to throw LOTS of money at this lump if you ever intend to use it. A GOOD used one will be cheaper than repairing this.
Take off the ///M colored glasses and run away from this broken POS

[White94RX]

Good advice from both responders. I agree with both.

[TostitoBandito]

Not to mention that S54 swaps into E36's aren't just plug and play. It's well documented in many threads here, and is a lot of work involving custom wiring harnesses and a lot of other work to make everything fit and work correctly. Plan to spend north of $10K to do that swap right if you aren't doing the work yourself.

[WadiM3]

Just to add that the exhaust system is a pain in the backside to find and fit. Agree with all of above. I just recently done a rebuild on a m52b28 and turned it into a 3.1L I ended up spending £2500. When Rebuilding an engine suddenly mysterious items come up that need to be replaced, not to mention all the bolts inside the engine are one use only bolts if I'm not mistaken.

[bmwdirtracer]

And that about wraps it up, doesn't it, folks? The answer is no, don't do it.

Run away.