how long can an m42 go

[Lenwood]

looking at a 91 318 with 222k miles. yes the odo works. been maintained. my question is how many miles are these motors good for with proper maintenance?

[roguetoaster]

I'd assume 250-300k before you should rebuild it. Mine has about 240k on the bottom end and is only now beginning to feel a bit tired, which could be a result of the last ~10k with a 4.45 rear end. That's not to say that it's worn out, but I feel that a leak down or compression test would yield results I wouldn't really want to see.

EDIT:

I should add that when I posted this the thermostat was not allowing the car to come up to full operation temperature, which may have colored my otherwise rosy opinions of the M42. After replacing it I believe the car has all of the pep back that it was missing.

[uturn]

Mine has ~217k on it and still performing DD duties. Had a burnt valve around 190k so did a minor head refresh then. All parts collected for a major overhaul, just need to find the time.

[TobyB]

A long time, if the timing components get done.

Otherwise, they tend to give out after a couple hundred thousand...

t

[aintnothang]

Pulled a cluster from a 318i in pnp made it to 368005.

[getouth]

I currently have 272k on mine, stock bottom end, head was rebuilt along with timing components at 217k. It is rock solid doesn't burn any oil and it's chipped to 7200...... I take it there regularly. If it has been maintained it will last! someone sold one on here last year with 440k if I'm not mistaken.

[E30Nutz]

My boy's '93 has over 350k miles and still running like a champ

[bmwm42]

Mine had over 400k

[varg]

Mine has 15X,000mi on the odometer, so let's say 200,000+ real miles, and I'm punishing it with a turbo. Lots of blowby. Failing timing components or a cracked head are the typical death knell of M42s, though crank walk can happen too. Just like most other engines made in the last 30 years, it will easily go 200k+ if it is maintained, but it's no stellar, long-lasting, ultra-durable piece.

[nk1221]

Mine has over 260k on it right now and runs perfect. Bone stock and has never had any engine work done at all. PO used it for commuting and its still a daily driver. The way its going right now I expect it to make it to 400k no problem.

[fresh_TD]

When properly maintained, it will burry you.

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[MVincken]

my engine had 330k km (205k miles) on it when i decided to rebuild it.
that was completely unnecessary.

even the head was pressure tested and completely no leaks on it.

[MouseRat]

I just passed 135k miles yesterday in my 91 318is. When I pulled the valve cover a couple of weeks ago the guts looked pristine. I think with proper maintenance 250k+ should be pretty easy.

[Harvey909]

I just bought mine last week and drove it from arizona to california the odometer stopped at 325k. I had my friend follow me all the way just in case it gave up during the 5 hour drive. But i had the AC on the whole time being 117 degrees and drove between 70 and 80 mph and had no problems the whole way. The previous owner really took care of it. Ive been driving it everyday to work and have had no issues yet.

[vpilarrt]

300k+ (odometer is sporadic), replaced timing chain & components a bit ago.