My wife's Corolla 1.8L (similar technology and design to the B18B engine) has some nasty stuff built up inside the radiator. This weekend I'm doing a major overhaul on the entire cooling system, including radiator replacement with brand new, complete system flush, and new heater hoses (radiator hoses are already fairly new).

I plan to flush the engine and the heater core separate from one another. I'm replacing the heater hoses to make sure I have new hoses without a bunch of crap built up inside them. My concern is the other hoses on the back side of the engine block that I don't plan on replacing at this time.

I'm wondering if I should use some type of chemical "flush" product to flush the crap out of the water passages in the engine and in the heater core. I will not be flushing anything through the new radiator since it's, well, new.

Has anyone used or can recommend any particular chemical flush product?

 

Don't use any "chemical flush" products. Just keeping it simple with distilled water and finish it off with some Prestone.

 

I can't exactly flush with distilled water, though. I plan on using the garden hose to flush and then drain all the water out of the block and hoses, then refill with 50/50 Prestone and distilled water.

I'm just concerned of possible gunk being built up somewhere that might contaminate the new radiator and new coolant. This happened the last time I flushed the coolant on this car (didn't replace anything except upper and lower rad hoses). The gunk in the radiator turned the new coolant brown within minutes.

I'm replacing the radiator and as many coolant hoses as I can, plus timing belt and water pump, but I'm still concerned about build up elsewhere in the system.

This is what it looked like the last time I flushed the system.

 

A chemical agent will do more harm than good. you will never completely flush out the system as there are passages in the head/or block that will always hide dirty little secrets. How you do this flush depends on your intentions with the vehicle. How much are you willing to invest? How long to you plan to keep it??

 

I would flush it out all you can with distilled water, change all the parts, run it a short while, then flush and possibly repeat that until it becomes satisfiable. Like DCFIVER said, you wont be able to get to all the cracks and crevices inside the block and head, but you will probably get most of the gunk out by repeated flushing. hope that helps.

 

How would you flush with distilled water, though? The water needs some force to get through the system. I typically just use the garden hose, which I know isn't good to remain in the system, which is why I always make sure to drain the radiator and block again after using the garden hose.