I have started seeing black ash sort material building up in my coolant reservoir.
I would clean up and it would build up around the surface of the container. Its not a big deal but I am curious as to what it is and where it comes from.

1. Buschur 2l built block and head. about 40k miles
2. Fp black turbo about 10k miles
3. coolant was completely flushed out. looked normal, but still builds up the powder.
4. there is creamy white residue under my oil cap sometimes

thanks for oyur input!

 

sounds like you have a blown headgasket.

 

is there any other tests i can run to confirm this before i start taking the motor apart?

 

Cmpression test, or leAk down test.

 

Yeah go to autozone and rent a compression tester, not sure if they have a leak down tester you can borrow too. I just went through this, first saw the black powder then the milky oil cap, then a bunch of white smoke. Have you overheated at all lately?

 

over heated, yes.
did a compression test and had no issues.

 

Then i would suggest doing the leak down test and see where that puts you. oil in coolant and coolant in oil has to be head gasket

 

does overheating the car cause head gasket to fail?

 

Other way around, the headgasket failing causes the car to overheat.

 

A couple other test you could do. You could pressurize the cooling system and see if you have a gradual pressure drop( would be through the hg). Also they have thies small paper tabs you can buy at autopart stores that you place on your coolant and it will indicate if you have exhaust gasses getting into your cooling system( coming through the hg).

 

It definitely can. And with white residue I would be almost certain your head gasket is failing to some degree or another. Probably not very sever at this point, but will get worse quickly. A compression test wont tell you the complete story because its not seeing the heat or load it would see under normal driving conditions. As noted before a leak down test would be your next best option,but can still be misleading for a slightly bad head gasket. Leak downs are better at checking for bad valves or piston rings.
Your best course of action would be to pull the head, have it decked and replace the HG.

 

Yes a blown HG will cause the car to over heat, but over heating can certainly cause the HG to fail. I have seen it many times on EVO's including my own.

 

Its probably headgasket.