Thread: OK to pressure wash inside water galleries?

I think you'd be better off to just use a hose on full. The pressure washer is great as a direct blast but the flow is not high so once it goes around a corner it's just a minimal spray - depending on how big a washer it is!
I'd attach a hose to the BOTTOM outlet and reverse flush it. We used to have a connection where air from a compressor was also introduced at this point.
Also when you first use the motor, try making a fly-wire strainer to catch stuff as it passes into the top of the radiator. This is temporarily placed in the top hose - don't forget to check it! (I've seen commercial filters that fit here too).

Dave

Turn the heater control to cold or you could flush any chunks into the heater core and block it. If the block seems reasonably clean, ie, not too many big chunks of crud, flip the heater to hot and flush the heater core as well.