Firstfives.org

Now that I've decided to keep this car, I've been looking into sourcing a motor.

The first option I've come across is a 3.5 from an 88 635i. I can get it with everything, including power steering pump, the brain, harness, etc. It's a great motor w/ low miles and good compression.

From what I've read in the Tech FAQ, any 3.5 up to '89 is more or less a direct bolt in. Can anyone tell me from experience that this is the case?

I have a five speed and drive-shaft from an '81 528i that I would be using.

What would I use for a radiator? The one I currently have in the car is brand new - would I need to replace it?

Is there anything else I need to plan on in terms of parts or converting?

If this motor doesn't make sense, what is the most sensible option? Once again, looking at the TechFAQ, this would be a motronic setup so I would be getting both the bigger displacement and the efficiency and smoothness of this config...

Thanks for your help.

cheers,
Brian

I am no expert on this issue, but have a few notes to share.

The 3.5L motronic motor should be great. Check out the article in the FAQ.

The E28 5-speed that you want to use does not have a hook up for your stock E12 speedometer cable. Usually, people use a 5 speed (gertrag 265) from a 1980-1981 E12.

It's a 5-speed from an E12 - there's a threaded port for a speedo cable.

thanks,
B

braino wrote:It's a 5-speed from an E12 - there's a threaded port for a speedo cable.

thanks,
B

oops...need more coffee. I guess i read 528 and thought E28...doh.

I know how that is

There is a parts interchange list in tech FAQs. My '79,'81 528's, '79 635 use radiators that all look the same to me, save the 635 has a lower hose flange w/different sensor.

I've goofed thinking 530's were mostly the same as 528's before. In my experience, a clean, stock radiator and cooling system, aux fans, fan clutch up to spec, works just fine in 100 degree humid traffic.

E28, aluminum, bigger, better flow, shrouds, water wetter, are performance choices involving set up and money, necessity hasn't made me consider.

That would be a very good upgrade. With it and it's wiring and ECU, you would not need a motronic bellhousing as with earlier motronic versions. A 635 would have the ECU mounted in the right place so the harness would work well. It will bolt up to your tranny just fine. 3.5's don't seem to generate any more heat than a 2.8 so if your current radiator is fine, it will be fine. You will have to swap the thermostat cover to use the early radiator, and E12 hoses. Motor mounts should be in the right place, unlike later B35s All of this applies to an 88, not an 87 which would need a motronic bellhousing.

You cannot beat the '88 and '89 E24 motors for this application. No adapters necessary to mount it in the car. The hardest thing to do will be mating the engine wiring harness with the fusebox, but I'd think enough folks have done it now that the info should be around!

Good luck.

That's great. I'll probably buy the motor today then.

It sounds relatively "straightforward".

Are 88-89's not motronic? I guess I should look this up...

Anyone out there have firsthand experience with the fusebox wiring? It would be great to go into this with open eyes.

Christopher - have you actually completed this swap?

cheers,
Brian

88-89 are motronic, but a different version than 82-87. The later ones use a pickup off the front crank hub, not off the flywheel, which makes swapping in an earlier car easier. It's also considered to be a much superior engine management system.

Not to mention better drivability and more power.

Thanks for all the help with this. I'm really excited about getting this work completed. I'm taking a week off in mid-December and I'm hoping I can get my 530i back on the road by then so I can drive it.

I bought the motor on Friday and it's on it's way to the shop.

I already have a project in my garage so I'm having a local BMW mechanic do the heavy lifting for me. We've established a budget up front and I figure if things get out of control I can move the car to my house and complete the work there.

I'm going to head over when the engine shows up, do some cleaning and take photos.

Anyone have wiring diagrams for an '88 635csi / B35? I've been looking around and haven't found anything yet.

cheers,
Brian

Can I use the shifter from my four-speed or is it different in a 5? I read something yesterday that seemed to open up some questions around this.

If I buy a short-throw kit would I have all the parts I need for the conversion?

thanks,
Brian

The shifter console for the four-speed is much longer. The lever is the same, but the selector rod and such are different.

If you have a parts car with a 5 speed, the correct shifter support and shift rod should be on it. As Chris mentioned the 4 speed parts are much different.