The description of the coolant boiling could mean a bad radiator, water pump, thermostat or a bad head gasket, as all of them can cause it to overheat.
Approximately how long does it take to overheat? Five minutes, twenty five miles? If you top off the coolant and then watch it after you start the engine do you see bubbles in the overflow tank?
Probably the first thing I would do would be to flush the cooling system. That means removing the thermostat (test the old one in boiling water to see if it opens at around 195 degrees, if it does not it may be the reason for the overheating) and cycling water through it until it comes out clean. That will flush out the stop leak and possibly any loose sediment in the system. Then install a new thermostat and start the engine and wait until it reaches operating temperature. Now if the thermostat tested bad, does it still overheat? If not then drain the water out, refill with coolant and drive it.
If the thermostat tested bad then you have another problem. At this point I would do a pressure test and a combustion gas test. Those may show a leak or that you have a head gasket failing.
https://www.2carpros.com/articles/head-gasket-blown-test
Next would be to see if the water pump is working. For that you can sometimes look into the radiator cap with the engine running and see the flow. Or you can feel the hoses to the heater core, they will be the first ones to get hot coolant.
If it shows no leaks or head gasket issue then I would probably swap the radiator as it could have areas that are plugged from sediment/rust/sealer.
I will also say that usually stop leak does not work, except to block up parts you did not want plugged like the heater core or radiator.
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Friday, July 20th, 2018 AT 5:47 PM
