Thinking about flushing out the heater core before it gets too cold outside, my heater isn't very hot, just warm.

Would it be a good idea to go ahead replace the heater inlet and outlet hoses as well? They are not leaking, but they are old, probably a fair amount of gunk in them.

 

If they are old, then yes, I would.

 

Use a hose with good pressure. Take in turns going one way then the other. Also have a go to blow all water out between flushes either with your mouth or a compressor.
Make sure you have selected HOT on your heater control before starting.

Mine took about 20 flushed before it was totally clean and now it gets really hot and much much quicker!!

 

Thanks for the advice!