Installing a new radiator as old one is leaking at seam. In the instructions for the new radiator, it says that after installing the new rad the "entire cooling system needs to be flushed with proper flushing chemicals using an approved flush + fill machine or kit" and "failure to completely flush system will void the warranty on new radiator.".

Can't I just drain the old radiator (and block by removing lower rad hose) and that will remove all old coolant?

 

No lol, that won't even remotely remove ALL the coolant out of the entire system (including block and heater core). The reason for this is so certain types of coolants don't get accidentally mixed, as they react with each other and gel. You could do as you asked, but they have spelled out what the warranty requires; up to you to either preserve the warranty or ignore it.

 

How do you fully remove all the coolant? Have heard the engine block drains are almost impossible to remove on an older vehicle - do I need to buy a kit or can I just remove thermostat and put rad end of lower engine hose into a large container and do the add water, run engine to drain some fluid, and repeat method until only clear water is coming out into container?

 

Pull the thermostat, leave the lower hose disconnected from the radiator, and just stick your hose in the top of the motor. Leave it run until the water coming out is clear. That will get most of it. Still need to flush the heater core circuit though.

Flushing chemicals aren't what they used to be...... Various regulatory agencies have made sure that the chemicals don't work nearly as well as they used to...... But, once you have 99% of the old stuff out, put the cooling system back together, run the chemicals/water, flush it out again, and you should be golden.

 

I've found that with most vehicles, if you point the nose downhill, you can get damn near all the coolant out and the little that's left shouldn't matter. Still, you can flush it with a hose and chemicals, but make the last flush distilled water. For vehicles with heater valves, turn the temp all the way hot. My Dakota doesn't have one so it doesn't matter. Not sure about the Rams.

 

Remove thermostat and lower rad hose. Use a shop vac and blow air into the thermostat housing. It will blow most of the water out.
Good time for new radiator hoses and thermostat anyway.

 

When I changed my radiator I used this method:


You basically drain out as much coolant as possible, then refill with distilled water. Run the engine, and repeat as many time as necessary until all you drain out is clear water. Then add concentrated 100% coolant to get the right 50/50 mixture.

Id recommend getting a coolant tester; they're cheap and help you know you have the right ratio of coolant:water. The cooling system capacity for the 3.7, 4.7, and 5.7 liter engines is 16.2 quarts.

 

When you say stick the hose in the top of the motor do you mean through the top rad hose that's disconnected at the rad or should I disconnect top rad hose at the engine and feed it in through there?

 

Either way. The idea is to circulate enough water thru the block that you clean out all the nasty stuff.

 

Finally got time to do this today after setbacks with the brake lines blowing, front calipers seizing, and some other stuff prevented me from installing the new rad until now.

Starting out with the chemical flush with the old rad still in so the system is clean before the new rad install and I've hit an issue right away - Ran the vehicle to circulate the flush chemicals and topped off distilled water and after 20 minutes the lower rad hose is still cool, top is hot, and overflow did not drop in level as expected when the thermostat was supposed to open. Upper hose was hot and heater blew hot air after only a few minutes so heat works (had it on hottest setting and full fan speed). Coolant temp gauge stayed at the halfway mark.

So seems like the thermostat is stuck that's why the lower rad hose is remaining cool and level of coolant didn't drop?