Is the only way to fill the radiator through the overflow tank?

 

It's the only good way since the radiators are capless.

 

I figured as much, gonna do a flush and refill. And didn't know if taking the top hose off to fill would be any faster

 

Taking the top hose off won't do ya any good for speed. The overflow tank is the only way. It's a closed system. Make sure you "burp" the air out of your system. I just did mine 3 weeks ago and have had no issues in 115-120 vegas heat.

 

How do you burp it? Just squeeze the hose?

 

Just do a drain and fill. Drain all the coolent from the raidatior and the block. Their is two plugs on both sides of the block you need to take off to get all the coolent. Pick up a bottle of Prestone Flush. Put it in and top of with water. Drive around for about a hour and drain it again. The Perstone Flush breaks down all the grime and crap in the system. Fill up with a 50/50 mix of green antifreeze. Burp the system. With the cap off and your truck running turn on the heater full blast and let all the air trapped in the system come out. I did this last year and didn't have any problems. Good luck.

 

What he said. That's how I did it. You will have to wait some time (about 10-15) to get all the air out. Watch your temp gauge. If it starts to rise past halfway and no more air is coming out of the tank, turn off the truck, wait a few seconds and then start it up again. That should clear all the air out. As the fluid level drops in the tank, add additional coolant/water to keep it at the appropriate level.

 

Where are the 2 plugs located? They are on the block not the radiator right?

 

The plugs are on the block. Here in the rust belt I find it easier just to flush through enough distilled water (making sure the thermostat opens) until everything is known to be flushed several times over and then refill with 100% until the concentration desired is reached. If you do a full flush you can go back with green coolant or switch to G05.

 

Put petcocks in place of the 2 screws you take out of the block, it will save you a lot of time next time you want to drain the block. Slightly tapping on those bolts with a ball peen might shock them enough to help them come out easier since they have been in there from day 1.