I took it in, and they ran a diagnostic on the cooling system, and replaced the thermostat housing. It overheated again about a week later, and they replaced the radiator cap. It overheated again about five days later, and when I took it back they let it run for about 30-40 minutes, but it didn't overheat. They said the fan is working properly, and kicking on when it should. They couldn't find any other problem. However, when I actually drive it and the car is in motion, after about 20 minutes it starts to overheat, and you can actually hear the fluid bubbling. Do you have any idea what could be wrong?
My car has 102257 miles.
My car has an automatic transmission.
Hi there - there are a couple of possibilities. The simplest and most likely possible case, based on the recent thermostat replacement, is that the cooling system was not properly bled of air pockets, and is boiling coolant inside the engine (the gurgling sound you hear), much like a teapot. Bleeding the coolant system properly will cure this scenario. The more serious possibility is a blown head gasket, whereby engine combustion is leaking into the cooling system, "super-heating" the coolant, causing it to boil internally. This will require a more serious repair job. I would recommend having a Car Is Overheating Inspection completed by a mobile, professional mechanic, such as one from YourMechanic, to diagnose this problem, get an accurate assessment of damage and cost estimate for repairs.
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