how many miles is too many on an M30?

[Gadea]

I´m currently looking for an engine to go into my E30 and I came locally across a 535i with a complete running engine (it´s missing a bunch of things I don´t need, like front doors) for $600. But it has 209xxx miles on it. Should I go for it? I also found an m50 with its wiring harness and ECU, less miles (180k) for less ($500). It also comes from a 525i, so I don´t need another oil pan and related parts. Also running, but I wouldn´t get what´s left of the car (as opposed to the 535i), just the engine. All of you who have done the swap, what do you think?

[E30SPDFRK]

Should be fine, but do a compression test to be sure. Mine had 253k on it and still had the factory cross-hatching on the cylinder walls and made 170 compression across the board.

[Gadea]

how do I do that? so, basically all cylinders must make 170 + or - 2 ? I´m guessing it´s PSI the unit you´re talking about.
I feel more inclined towards the 535i with the M30. The whole M30 swap seems to be a smoother, easier, cheaper process.

[Jonsku]

Actually M50 is much easier and the engine itself is 20 years newer technology..

Anyways, M30 can make 500k miles easily with only oil changes and cleaning oil channel on the valve train so no problems there. So can M50 (but hydraulic lifters and chain tensioner have to be changed couple of times for that kind of mileage) so no worries there..

[Lurker27]

The headgaskets tend to go around 250k.

I rebuilt a 300k engine this summer and some of the seals were basically useless (rear main was awful but somehow not leaking) but most of the condition of the metal parts was flawless (not much wear on bearings, original crosshatching, 170-175psi compression across the board. Engine pulls strong and leaked/burned no oil even at that mileage.

[Jean]

Which one is easier depends on what parts you have at hand.

M30 is easier since you don't have to deal with specific booster to clear the manifold.
The harness plugs right into late model e30 c101
Exhaust can work with 325i rear section, e32/e34 downpipes clear the subframe/sway bar etc...

M50 is easier in the way that you don't need custom engine mounts
That it's not as "long" so fitment is easier

M30B35 > M50 in terms of torque....
24v > M30 in terms of it being a smoother running engine, not as loud as SOHC 12v.

But with 200k miles I wouldn't trust either engine w/o doing a good inspection/leakdown.

[Gadea]

thanks guys for all the input so far. I´ll be tomorrow taking a look as much detailed as I can to the 535i. I heard a lot of praise to either engine. I agree with most of you. After listening to both, seeing them in action and watching countless swap videos on utube, it´s evident that the M50 while ages ahead on engineering, it´s more of a "refined" or "tamed" powerhouse with its purring sound. It´s without a doubt more expensive too when it comes to repairs or upgrades such as M3 parts, Schrick cams and all that. The M30 strikes me as a wild beast (more like a dinosaur) on the loose when coupled with the boxy and sexy E30. Nothing too subtle about it. Just raw powa !! I hear you also about the engine size issue, as well as mounts, I´m just not too concerned about it as much as I am customizing a wiring harness for the M50/52. I most likely won´t be seeing any track time anytime soon, and won´t be trying to impress any refined ladies with a newly installed M52. I settle with wifey not arguing anymore about money being spent on bmw...So even though I have an E21 320i brake booster waiting, (it took a lot of time finding one) I´ll go the M30 route if everything goes according to plan. That doesn´t mean you can stop. Keep the opinions coming. Hey, nobody said a word about transmission. Maybe it´s time to ask...What kind of issues can I expect to run into? Thanks a lot!