83 528e -> 89 325i motor swap

[BDSax]

how difficult would it be to swap a 89 325i motor in a 83 528e? e28 motor is taking a crap, i redid the head and it still bad, i think the block may be cracked. so im swapping a m50 into my 325i. ill have a good running motor from the e30.

will the e28 trans hook right up or can i use the e30 trans, both are autos. i know ill need to change the ecu. any help is needed. thanks!

[Erick]

Man, you just love piling up engine swaps :)

[JGood]

If your e28 has bell housing-mounted flywheel pulse sensors, there will be no provisions for them in the 89 m20b25 transmission. Only eta tranmissions had them.

I don't see why you'd need to change the ECU's, the trans has no electrical inputs. The ECU has no effect on the trans, and has no inputs to know what it's doing either.

I just picked up a spare eta motor with good auto trans that I don't want, if you want it. PM me with an offer, I'll let it go REAL cheap. I'm in PA.

[Erick]

He's not doing a 5spd, he's just swapping the motors. And you need the ECU for the i motor. He wants to know if the M20B25 bolts on to the 528e's auto tranny.

I'm 90% sure it will bolt on to the tranny, but I cant confirm it.

[JGood]

He's not doing a 5spd, he's just swapping the motors. And you need the ECU for the i motor. He wants to know if the M20B25 bolts on to the 528e's auto tranny.

I'm 90% sure it will bolt on to the tranny, but I cant confirm it.

ehhh... yeah I messed that up.

So the 89 trans is electronically controlled from the ECU?

The manual transmissions are the same bolt-up wise, I don't see how the auto's could be different. But the manual tranny's have a different flange thickness between the eta and i, so check that.

[euroshark]

I have to ask, sorry if I offend anyone...

Why would you put a torque-less, high-revving motor (relative to the M30) in an E28 chassis? I have to rev my 533i more than I would like, and it still puts down way more torque over a much wider range than an M20...

I guess I see why, your eta motor is dying and the i is a direct replacement, but with the cost of M30s I wonder why you aren't considering one of those instead? Your E28 is gonna be slllllloooooooowwww with a 2.5 i motor, and off the line is where it will really be noticable.



Edit: I just saw that it's going to be stuck to an auto tranny?? I seriously think you will regret that swap.

[BDSax]

well, i guess ill keep the e28 tranny. i need the motronic 1.3 wiring harness and ecu for the 89 m20b25 motor.

i figured since my motor in the 325i is running strong and i know its in good condition, i might as well put it in. that is if it fits correctly. does anyone know if the motor mounts are the same?

personally i just wanna sell the e28 and get something newer, but my wife loves it to much. she also sees me putting a new motor in my car, so she says she can put a new motor in her car.

cant argue with the boss.. hey erick, ready to do 2 motor swaps?!?!

[BDSax]

I have to ask, sorry if I offend anyone...

Why would you put a torque-less, high-revving motor (relative to the M30) in an E28 chassis? I have to rev my 533i more than I would like, and it still puts down way more torque over a much wider range than an M20...

I guess I see why, your eta motor is dying and the i is a direct replacement, but with the cost of M30s I wonder why you aren't considering one of those instead? Your E28 is gonna be slllllloooooooowwww with a 2.5 i motor, and off the line is where it will really be noticable.



Edit: I just saw that it's going to be stuck to an auto tranny?? I seriously think you will regret that swap.

wife dont like stick. she also things the m30 will use more gas. and i will have a m20b25 just laying around!

[euroshark]

Use the E28 motor mounts, I think they may be a little different. Probably use the motor mount brackets too... Other than those things, it should be a direct fit.

[CarsSuck]

if the other internal parts, namely the crank, are in good shape why dont you put together a cheap 2.7i motor?

[BDSax]

because i dont wanna put anymore money into this thing. id rather put it into my e30.

[CarsSuck]

if its just a couple hundred bucks to get it done and have a good reliable engine for wifey, do it. Otherwise, i agree, fuck it. If its a cracked block, swap the blocks and be done with it. Rebuilt head will take it far enough.

[BDSax]

i already spent the time and money to get the head all done. i dont want to screw with taking it all apart again