Question from newbie E12 owner choosing between engine options

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jazzrod
Posts: 2
Joined: Thu Feb 20, 2020 3:16 pm

Question from newbie E12 owner choosing between engine options

Post by jazzrod » Mon Feb 24, 2020 6:35 pm

Hi all,
Great forum you have here!
I've recently bought a non-running 1979 (11/78 build) 528i auto, in Melbourne, Australia. It needs a new engine as the M30B28 (original I believe) has poor compression in several cylinders and clearly hasn't had regular oil changes. Could be rebuilt, and I may do that, but looking to swap the engine to get it drive-able first.

I have several options and have been reading about the merits of the different upgrades, but I am basically down to two.

M30B28 from an 83 E28 - different intake and I assume motronic injection, no transmission but has torque converter attached
or
M30B35 from 88 E34 535i with matching 4 speed auto gearbox (not sure of model yet but from the same car)

I am actually located in Hobart, Tasmania, and it will cost more than the car was purchased for to transport it to me when it's not drive-able, so I'm getting a Melbourne based mechanic to do the swap.

So, my question to anyone who wants to offer an option, is - Is it dramatically less work for the mechanic to install the M30B28 from the E28 and re-use the intake/injection from the E12, than to install the B35?

Obviously it would be more work due to the transmission and harness changes, but I guess I am wondering if the extra work involved is small enough to justify having it done upfront while it's being worked on.

Thanks in advance for any suggestions or advice!

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keehn
Posts: 88
Joined: Tue Oct 01, 2019 5:14 pm
Location: Martinsburg, WV

Re: Question from newbie E12 owner choosing between engine options

Post by keehn » Mon Feb 24, 2020 9:03 pm

Jazzrod,

I would recommend you replace the M30B28 engine (e.g. the head/block assembly) itself. The M30 block in your 1979 is effectively the same as the M30 from the 1983. All your mechanic has to do is swap the engine with minor modifications (e.g. motor mount brackets, upper timing chain cover which holds the distributor) and it will work just fine.

Now, if you want to upgrade your 79 to an E28 motronic setup, then I would look at http://firstfives.org/faq/e28_wiring_co ... rsion.html to see what's involved with moving the E28 wiring as well.

Mike

jazzrod
Posts: 2
Joined: Thu Feb 20, 2020 3:16 pm

Re: Question from newbie E12 owner choosing between engine options

Post by jazzrod » Tue Feb 25, 2020 3:41 am

Hi Mike,
Thanks for that.
I definitely understood that replacing the block/head/engine itself was necessary - the existing engine has multiple issues and could not be used without a full tear down and rebuild.
Between my initial post and your reply I've actually located an M30B28 from an E12 (same year also) so I think I have an immediate minimal effort swap option in hand now. However, once I sort out the interior and clean the car up generally I'll be on the hunt for an M30B35 with manual transmission as an upgrade.

Thanks again!

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