M50 swap, M42 Air Conditioning
 

First off, this is the first time (and will be the last time) I've ever let someone else swap an engine in any car. I got a deal on the swap and labor for around $1200 and I figured "Hey, less headache as I've never really dealt with BMW swaps" but this guy drug his heals for weeks on it and in the meantime I was driving his spare 5-series wagon (that was constantly overheating and was one of my first tips that this guy probably was going to do some shotty work).

At any rate, engine is in and running strong, I need to run down the CEL that's related to the O2 sensor either being bad or not properly hooked up. He put my old working AC compressor onto the M50 and ran the lines but told me that I needed to source a different tensioner in order to get it to work. My question is: Is this correct, if so what do I need to get because just getting any answers out of this guy is like pulling teeth and it's 103 degrees here today!?!

Thanks in advance for any answers, I searched but didn't come up with my specific question, they were more related to running the lines.

I think you will need the compressor and mount bracket (if it was missing) from an M50 for that A/C to work properly. Also need to change the hoses from the M50 as well.

Maybe it will work, but probably the aalf-hassed way to do it if it works at all...

It's mounted up and lines are run, I just haven't tried to charge it. I could give that a whirl to see tomorrow however I may be wasting a couple bucks too. Crossing fingers or I suppose I begin my search for a compatible compressor because August is HOT here, lol.

You need a vacuum pump to pump out the system before you charge it.

The charge has to be dead on or the system wont work, you'll need a regular gauge setup to charge it the refills don't work very well.

On mine the spread on the pressure is less than 10lbs pressure or the compressor wont start (Too low charge) or stalls (Too high charge.)

Cheers.

Dave

Bumping this up. Swapping my 6cyl into a new chassis that has more features than mine and researching a couple things.

My current swapped car has no AC with all lines removed. I'd really like to keep the AC in the next car, there's a couple instances when I'd love having it.

From the above, it sounds like the common method to retain AC with a swap is to get the AC compressor from a 6cyl? Do they vary between the 6cyl and 4cyl, or is it a different mounting bracket only?

I've already found that retaining cruise control requires the 6cyl actuator, but haven't dug up anything on retaining AC yet.

Sorry, I should have updated this a long time ago, lol.

I did end up running the AC system from my M42, vacuumed out and recharged and it blows as expected. Some of the biggest differences I found from running a 6 cyl in a 4 cyl car is that your tach reads wrong (most folks drive by ear anyway, but swapping in a cluster from a e36 325/328/M3 will also solve that problem), my car reads hot despite it not being hot, just need to get a new thermostat but that doesn't bother me much. That's about that.

Just trying to clarify. You used the M42 compressor + lines? What did you use for a mount to the engine, and what did you do in terms of pulleys and belts?

I'd guess the easiest way to do it is just bite the bullet and get the 6cyl stuff, but it'd be nice to reuse the 4cyl stuff.

4 cyl compressor and mount bracket are totally different. I think even the belt is a different size...

My experience indicates the compressor, mount, lines, pulley and belt all must come from a six cylinder car. I used M3 parts in my case (on M roadster/M3 engine), but the 328 parts are most likely the same, and therefore most likely will work fine.

M Roadster compressor, bracket and lines are also different and also not compatible with te ti.

I used a different idler but that was it. Not sure if there's a difference between the M42/44 but with a little adjustments I kept my air system as the M50 I received was put into an E30 cabrio with the intention of drifting but that never came to fruition for the former owner. He had stripped a lot of parts he deemed "unnecessary" in that process, getting the proper oil pan was the biggest deal for me at that point.

That said, the AC was the one thing that didn't actually go wrong for me to date.