Chevrolet Repair: radiator problems, radiator problems, radiator fluid

Question
First I want to thank you for you response.  
I just stuck a water hose into the radiator to fill it up and left it in while I looked very closely at my radiator.  I found water flowing out from the top right corner of it (while looking at it from the front of the truck).  The leak is coming from a spot that is right up against the grill of the truck.  I couldn't even fit my finger between the two.  Is there a product that I could try that would plug this leak?  I don't have a lot of money to spend on an a 15 year old truck.  Thanks again for your help.
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Followup To
Question -
I have an 89 chevy silverado, 100k+ miles.  Over the last few months the heater has been fluctuating between hot and cold, I was smelling radiator fluid inside the car, three days ago it overheated.  I filled the radiator with coolant, checked a few hours later for it leaking out of the bottom, there was no leaking.  I drove it about ten miles and it overheated.  When I got back home the inside of the engine compartment was wet with the fluid.  What could cause this?  I checked for kinks in the hoses and found none.  Could it be the thermostat?  Thank you very much for your help.
Answer -
Hi Daniel,
You might have air trapped in the system. Sometimes it can be hard to get it all out.
You could have a thermostat problem, but you could also have a water pump problem. That may be where the coolant is leaking.
Van

Answer
Hi Daniel,
There are leak stop products that make claims of fixing a lot of leaks, but I am a strong supporter of pulling the radiator and getting it fixed.
One trick I have used is to remove the rubber seal from the radiator cap, the one under the little check flap. That keeps pressure from building up and blowing out the coolant, yet lets it come and go to the recovery tank.
That can only be done if you don't work the truck too hard.

That radiator is real easy to get out, and the leak stop stuff could plug holes in the engine you don't want plugged, as well as loose its grip at the worst possible time.

Good luck,
Van