I have a 302 in my Early Bronco that I need to replace a head gasket on. So obviously I need to drain the coolant from the motor, but I want to know what is the best way to drain all the coolant from the block. When I was tearing down the motor to rebuild it last year I drained the radiator and pulled the lower radiator hose to get as much coolant out as possible. However when I pulled the heads there was still a lot of coolant in the block. Is there a better way to drain the block? And is it bad if I get coolant in the cylinders as long as remove as much as possible?

thanks

 

There should be some plugs on the side of the block to unscrew and drain some coolant out. I was able to on mine. If coolant gets into cylinder I usually stick some rags in there and dry rest with compressed air. And of course change your oil after doing the head gaskets. I've never had a problem with doing it that way.

 

if you dont find any plugs to unscrew, pull a freeze plug out and most of it should drain.

 

You have to drain each side independently, as draining one side won't fully drain the other. But you don't have to drain it completely anyway, just enough so it doesn't drain back in the cylinders. It will have drained to this point anyway when the heads came off.

 

Just my experience with in car head gasket replacements- I just drain the system with conventional method (lower rad hose or radiator drain). The reason is even if you pull a freeze plug, etc., when you pull the head you're still going to have residual fluids dump into the cylinders and oil which has to be drained and flushed anyway.

 

I just opened the petcock on the radiator and let her go when I did the head gaskets on my Mustang. There was a little coolant spillage but that would be expected even if you drained the block.

 

The easiest way to drain the coolant is to shoot a hole in the side of the radiator.

Next best is perhaps the lower rad hose. The bottoms of the water pump inlets are about the same as the coolant passages in the block deck.

you are gonna mop up anyways and shop vac after you get done scraping off head gasket residue - right? right?

just spray each hole with WD 40 before reinstall - the heat of flames and explosions will take care of the rest (heck you can leave a used block out in the rain for a couple of months before any rust starts that is problematic.)

 

If you will drain the radiator, then turn the starter a little a few different times, you can often blow enough out to keep that side relatively dry. You will almost always get a little in the valve valley and cylinders no matter what you do.

If you have fresh oil, you can mop up the coolant quickly with shop towels and then run the engine a little before changing oil and filter. If you get more than about a shot glass full, you should probably start the engine for a half a minute or so to let the oil circulate and absorb the moisture before changing. If you get a lot more than that, you will need to change oil before restarting and then change it after warm up or maybe a trip around the block.

My $0.02,