M52TU to M54 Intake Manifold Swap and Cooling System Overhaul

[staggerwing17]

My new to me 1999 Z3 2.3, M52TU has 120K miles on it and is in need of a complete cooling system overhaul. The process has been quite smooth - a California car is so much easier to work on than one exposed to harsher climates. I have so far removed radiator, shroud, belt tensioners, water pump, thermostat, the coils, and the intake manifold. I have most of the parts to replace the removed ones including the M54 manifold. I am at the point of removing the 2 plastic cooling pipes that were under the manifold.

I have a bunch of questions:

1. What is the best way to clean the M54 manifold (used) as it has a dirty film throughout the inside and I realize it will just get dirty again but I want to start with a clean manifold.
2. The starter is now completely exposed. It works just fine but it is sure tempting to replace it given the trouble to get here. Is it worth replacing it or are the starters pretty durable beyond 20 years?
3. On the bottom center of the M52TU manifold, there is an orange rubber opening for what appears to be a valve of some sort. The M54 manifold does not have the same opening, just a molded 90º tube. Do I need to adapt a hose to get it to run to its destination?
4. Most embarrassingly, I removed a small diameter rubber line with a sheath - black with yellowish stripes. It is about the same size as a vacuum tube. It ran underneath the manifold but despite looking at all of my pictures and pictures on line, I do not see where it started and where it ends. It seems to be more of a fuel line or perhaps fuel vapors? I cannot find it in realoem so I am stumped. Any ideas? Thanks for your time and assistance!
   

 

[the Nefyn cat]

Just a guess, but would the hose in pic 4 be something to do with the CCVV, there's a blanking plug fitted to my M54s valve, but I'm sure I read somewhere that other engines have the valve connected to one of the ports at the back end of the inlet manifold. The valve is no.1 on here

https://www.realoem.com/bmw/enUS/showparts?id=CN12-EUR-01-2002-Z3-BMW-Z3_22i&diagId=11_6220

and the pipe may go to no.15 on here

https://www.realoem.com/bmw/enUS/showparts?id=CN12-EUR-01-2002-Z3-BMW-Z3_22i&diagId=11_6239

No guarantee that I'm right, of course.

 

[t-tony]

If your car has the so called "smog pump" it could be the vacc. pipe which goes to the valve on the cylinder head at the front right hand side.

Tony.

 

[NZ00Z3]

Hi

1) Some sort of water based gentle de-greaser sprayed into the manifold and washed out with water should clean it up.

2) Its up to you on replacing the starter, they are very reliable.

3) Yes adapt the hose to the new fitting. I do not remember there being a valve on the end to worry about.

4) The hose goes from the pressure relief valve on the fuel rail to the small port in the middle (side) of the Crank Case Ventilation separator.

Regards

Murray

 

[staggerwing17]

Wow thanks to @the Nefyn cat , @t-tony and @Murray Wall! It cleared 100 degrees F today so I hid in the garage, poking around. I found a little piece of the original tubing at https://www.realoem.com/bmw/enUS/showparts?id=CN12-EUR-01-2002-Z3-BMW-Z3_22i&diagId=11_6220 on the pressure regulating valve (#6, vacuum line). It goes from that valve to a nipple on the metal tube on top of the fuel rail as Murray surmised. The rest of the stuff attached to the manifold is a little easier to determine so thank you guys for your feedback!!