I have dex-cool antifreezer n my radiator but i need to change the radiator because one of the plastic tank is craked n the antifreezer was leaking so is ok if I change from orange to green antifreezer

 

Yes, but you need to flush all the Dexcool out of the entire system including the engine block.

 

What I need to do to flush the antifreezer from the engine block. I flush it before n I take the thermostat out the engine and run water through the upper radiator hose. these is the same way to flush it out the engine block, if so thanks for you help!!!

 

It depends on how you do it. If you connect a garden hose to the standard flush kit your engine may never heat up enough to open the thermostat so I usually remove it. Keep the hose going until all you have is clean water coming out of the radiator then do it a little more. I have a radiator cap that I drilled out and installed a hose bushing so coolant doesn't go all over the place. When done drain the radiator fully, reinstall the thermostat (or new one) then put a gallon of antifreeze in and raise the front of the car slightly. Add water or coolant till full. Keep the radiator cap off and run the engine until it's warmed up then keep it going for another 15-20 minutes which should burp any air out of the system. During that time you should also have your heater turned on full blast. If your heater doesn't work it's either clogged or has an air pocket in it. There are quite a few threads here on flushing heater cores. There are a couple of block drain bolts but I don't usually mess with them. That's just the way I do it and I'm sure real mechanics have their own method....and environmental issues to deal with that a home user doesn't...unless you have a dog. I only have rats with bushy tails so they're welcome to drink my coolant.

 

Thanks for the input Dobyken I just dome with my 12 hours shift work so relax for little bit n star working in the truck let you know how I ended...

 

Thanks for all the support Dobyken my blazer is running with new radiator n green anti freeze with the temp gauge in 210 degrees so is the ok. thank you so much for you help..

 

Short term it's not a problem but it should be at 195. Sounds like you still might have a little air left in the system or your thermostat isn't opening properly. I'd try "Burping" it a bit more with the cap off. Make sure you get the front of the truck up a good bit so gravity can do it's thing.