89 535i Engine Rebuild

I am starting to rebuild my engine. I was thinking it over and didn't know where to even start. So where should I? Besides the engine, anywhere under the hood. I'm looking to rebuild and add some power. Then I started thinking about swaping it out. There are so many choices and paths I could take, but do not know what would be most rewarding. Any suggestions? My engine has 180k and its starting to look pretty worn under the hood. Anything under there I should really be concerned about? Not much has been replaced since new. Where should I start??

Unless its been abused, it might not need a rebuild at 180K. Is it performing poorly? any specific problems? If these items have never been replaced on this car, then they almost surely need to be: air mass meter, idle air control valve, o2 sensor, throttle position switch, rotor, distributor cap, spark plugs, and spark plug wires. Fix any and all vacuum leaks on the intake side of the engine. These are tricky and can be hard to locate. Replace the air intake boot if it shows any signs of cracking, this can cause a less than obvious vacuum leak.

I solved most of my performance problems by replacing these parts on my 89 525i (M20). I also had a broken timing belt which led me to replace my cylinder head (bent valves!) consequently also replacing the head gasket, intake and exhasut gaskets, and exhaust manifold gaskets (to exhaust system).

Do a compression test to get an idea of the condition of the rings and valves. I am not much of an expert, but there are methods that will help indicate whether or not the cylinder rings are at fault, or if it is simply a valve job that you need. (I think its called a "leak down test") Certainly easier to pull the head and get the valve train refurbished than to pull the cylinders out for a ring job.

Oh yeah, if you pull it all apart anyway don't forget to replace the water pump!

Just my $0.02 worth. Have Fun! good luck!