Bought a b18b1 , took off the head and found all this corrosion in the block , also the pistons were very sorry, what can cause this? Is it fixable (worth it) etc? Thanks any help is appreiceited

 

The black on the pistons is normal, it's called carbon and carbon buildup happens in most all engines over time.

The coolant salts int he water jackets is also pretty common. People don't always change their coolant often enough.You should be able to dissolve the salts out with distilled water. The reason for distilled is it is the most pure form of water with the least amount of salts/minerals in it. It will absorb more salts and minerals than any other water (except reverse osmosis filtered water typically).

Fill the jacket up with distilled water. Let sit over night, dump and refill with more water. After a 2 to 3 cycles you should see the salts diminish. You can also use a bottle brush to agitate and scrub the walls.

Avoid getting water into the cylinders with the pistons. You might coat the piston cylinder walls with oil before adding water to help put a protective barrier.

 

Maybe someone tried some of that "Head gasket in a bottle" stuff and it causes some coolant coagulation?

 

Adding to TomCat's point,

Never ever put tap water in your cooling system. Over time, those minerals will deposit and cause exactly that. Your particular example looks like a case of neglect combined with topping off from a garden hose.

Change your coolant with Honda coolant every 45k, mix only with distilled water if you're not using premix.

 

What you see is someone using tap water. Honda Coolant does not cause that to happen and the reason I say that is because I took apart my sisters b18 block. The coolant passageways didn't have any buildup like that.