Took it on a very short road trip. I didn't notice the temp gauge, when I stopped for gas my overflow tank was boiling and spitting water everywhere. Now just driving it to the store on a hot day will cause this problem, going over 60mph even at night will cause it. A mechanic friend didn't really look at it, but said the waters coming down from the side by the tire, so it's probably cracked. I have no clue about any of this. I ordered a new overflow tank. Going to install today, but I'm worried there's another reason it's overheating. How'd it get cracked in the first place? Could it just do yhe same to the new tank? Can't afford a professional to look at it. Have to figure it out on my own. Please help.

208,000 miles on it, sat for years in a towyard til I bought it. Then another year in my garage. It was taken out and "power tested" a little here and there, but that trip was the most it's been driven for years. Before it ended up in the toward it was well taken care of. Performance parts added, rebuilt and well maintained engine. Check engine light has been on since I bought it, it reads oil switch sensor. I also replaced the radiator cap, the water boils through the cap.

 

Replace the thermostat for starters. Properly bleed the air out of the system. Make sure coolant is actually flowing when the engine is running and warmed up.

 

Planned on replacing the thermostat too. How do I check if the coolant flowing?

 

With the engine off and cool, remove the radiator cap. Start the engine, wait for it to warm up, you will see the coolant moving looking into it.