http://www.trustmymechanic.com/auto-repair/4345/head-gasket-repair-this-works/ (visit my site for more tips)
Did your mechanic tell you your car has a headgasket leak? I get TONS of questions like this everyday and many of them are NOT head gasket leaks. I made this video to help you determine if you DO or DO NOT have an internal coolant leak.
The FIRST, FIRST, FIRST thing you need to do is get a cooling system pressure test. This fast and cheap test will help you determine if you have an internal or external coolant leak.
If you are absolutely sure there are no external leaks, and the radiator is not restricted and the electric radiator cooling fans are working, then try this awesome sealer.
The product is called Engine Block Sealer, made by K&W. They have the old version in a hard metal can and their new and "improved" version in a green plastic bottle called Nano Technology. Both seem to work just fine.
I do not personally use the product as the instructions on the can say (been using it my way for years with a 75-80% success rate and its much easier)
My instructions for using K&W Block Sealer are:
1. Drain out all coolant from radiator as you possibly can.
2. Get a bucket and mix up the block sealer with tap water
3. Pour contents of the bucket into the radiator, top off with tap water
4. Then put 500 miles on the car as soon as you can
5. After 500 miles drain out the mix and reinstall coolant and water as needed
The seal should be permanent
You will NOT have boil over or freeze protection during this time period so please keep the engine from freezing and overheating.
And no, I do not remove the spark plugs or the thermostat as the can says.. Just the steps above.
Hope this helps, visit my sites for more cool tips and information