I see most instructions are to drain the coolant from the radiator only, and then replace/refill. With my motorcycles, we also drain from the engine. Is there no engine drain bolt for the G1500? Something close to the water pump?

I have a 1997 G1500

 

Check passenger side of cylinder between exhaust hedders 6 and 8 should be there

 

If you have tha Haynes guide, it's on page 1-23. It's a typical brass plug. Haynes also says there is one on each side.

You did not say why you are draining, so I can't give specifics. I changed the water pump last Oct on my '99 Express Conversion 5.0, and what I usualy do is just blow air into the the top radiator hose and the excess comes out of the bottom hose. If you need to drain it all, to say swap the engine use the plugs, blow compressed air into one ( low pressure at first ) and let it come out of the other. Maybe put a fuel type fitting with some 3/8 hose to let it spray into a container and not all over...I hate getting Green AF or DexCool on anything. That crap is so sticky and I gotta keep cleaning my hands....hehe.

--SteveMc