Will a new coolant radiator cap

Asked by Dec 01, 2013 at 11:02 AM about the 2003 Ford Explorer XLS V6

Question type: Maintenance & Repair

My heat gauge has been rising and falling quickly for a long time but only occasionally- mostly happens in cold weather or when I'm driving long distances on the highway.  Finally, yesterday, the heat gauge light went off for a couple of minutes until there was a popping/rickety noise.  Pulled over and there was boiling coolant pouring from the top of the tank through the lid.  I was at a gas station and in a rush to get to the airport, so I bought a gallon of undistilled water, poured it in after it cooled off, and took it easy to the airport and on the way back home.  Sears topped off my fluid but recommended a flush.  Now I'm looking for parts/options to really fix the issue.  Not sure if I want to replace the tank, hoses, or just try the cap first. Any suggestions on where to start?

3 Answers


I would start with inspecting engine for signs of a leak. Specially around the water pump. If leak found there then I would replace the water pump. If no leaks found and you have never poured anything like stop leak in your radiator (please don't use that stuff it just hides the problems and creates bigger ones in the long run) then I would start with testing your thermostat. If found to be faulty then replace it. Last but not least. You stated that it heats up on long trips on the highway then cools down quickly as you slow down. This is one sign of a possible head gasket issue.


Oh and yes a faulty cap can cause an over heating issue.

sounds like thermostat sticking would do that first cheapest option if no leaks from pump get new o ring for thermostat housing mine was leaking at housing after I replaced thermostat will save you from doing it twice.

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