Can somebody tell me what these two parts are?

 

A - oil pipe from engine block to turbocharger
B - water pump

 

Is it just one water pump?

 

The R56 has a mechanically driven water pump like the one in the picture and then an auxiliary electric powered water pump just before the turbo (between turbo and coolant tank).

 

Yep,

B. Should be noted its the main water pump. For the turbos they have an additional aux water pump. All noted here:

https://www.northamericanmotoring.co...8-no-heat.html

 

I see, so is it safe to say that when one replaces the Thermostat for leaking, this water pump is also replaced?

 

I would suggest the water pump and the plastic water tube between the pump and thermostat be replaced if they are original, since you are in there already.

 

I was told that the thermostat usually needs replacing because its made out of plastic and the heat corrodes the form and it no longer is able to seal tightly. Is this true?

 

I did them all at once so I would not have to do it again.

The thermostats develop a crack on the seam near the base or on the seam itself. For heat and time the material just starts to flex from heat cycles. The newer thermostat I replaced seemed to hold up better.

 

On my car the temp sensor went even though the housing was not leaking (yet?). You might be able to replace just the sensor but when you realize the thermo is a plastic POS that gets exposed to boiling+ hot water changing the whole thing seems reasonable since you have to take it out anyway. Since you have to take it out anyway, you need to unclip it from the plastic water tube that connects to the water pump. If that thing leaks you need to remove the thermostat to replace it. So might as well replace the tube with the thermostat. Last thing is the water pump, which is also plastic. Then you are all good for another 30k miles

 

Plastic my @ss, im sick n tired of using cheap parts to save money. They dont make cars like they used to damn it, its all about the money. Buying and replacing parts is what automobile companies want!

 

Since they want the car to run hot for emissions but not explode when under heavy load the plastic parts, and the various fluids, take a beating. I got a manic stage 2 tune partially because it runs the car at 90C versus 105+C. If you have a turbo and/or automatic transmission both are cooled by engine coolant at some point so lowering the operating temps are sure to help those components in the long run.

 

Interesting but what parts have you installed to have the manic 2nd stage tune? I suppose an intercooler at least?

 

stage 2 requires high flow air filter replacement, intercooler, downpipe replacement and nkg 1422 plugs (1-2 steps colder depending on what you have stock)