The 'end tanks' (sections on both sides of the radiator core) are plastic.

 

Okay, now were getting somewhere. That reply: "And on my blazer the plastic tanks on the radiator developed hairline cracks and the coolant would leak profusely when the engine was hot. U might want check that" Was indeed refering to the plastice sides of your radiator also called 'tanks' resulting in confusion.

Toaks1 has the right idea, aside from replacing your radiator cap check for leaks when your engine is up to temp. Some hairline cracks won't leak or be visible when cold. The cooling system is a 'high pressure' cooling system that is why the radiator cap is essential as well as having good hoses and gaskets due to the high temp and pressure. Aside from checking the radiator and hoses check the water pump for leaks too.

 

ok thanks, i will have to check all this stuff out... or just do it the easy way and pay the 70 bucks to get it pressure tested and diagnosed by a shop and then go from there. i checked all that i could check when i made it home today, and it was definitely up to temperature, but like i said it seemed like it was holding the water in, so i dont know what that means, its like its picky about when its gonna leak

 

Well good luck, still check what you can yourself, also why pay $70.00 just to check your radiator when for about $170.00 at Schucks/ Orielly's you could buy a new one but it doesn't make sense to replace parts without finding the cause of the problem.

Start with the cheap stuff first, also when was the last time you flushed your radiator?

 

Got the Pressure Test today, turns out it was the water pump, thanks for the help everyone

 

IN MY CASE THE RADIATOR OVERFLOW TANK HAD DEVELOPED A CRACK IT LEAKED DOWN HIT THE BLOWER MOTOR WIRES SET IT A BLAZE AND THATS HOW I FOUND MY LEAK.