Car overheats then returns to normal

I am having problems with overheating in my Dodge Caravan.

Problem: The temp gauge will go to halfway (which is where it normally sits) for a while but then after about 10-15 minutes (give or take 5 minutes) it will slowly (or relatively quickly) move towards hot. Sometimes it gets to hot, sometimes not and will generally stay there for a few minutes then work its way back down to normal. Today it got to hot so I pulled over and some coolant spewed out of the cap and more from the overflow container. Then after 5 minutes I checked the gauge and it had gone down to 3/4. I then started the car and made the short trip home. A couple of minutes later it was back to halfway/normal. The problem seems quite random but it does seem to be aggravated by working uphill or stuck in traffic.

The car does not appear to be losing fluid/coolant unless it gets hot and overflows. Both fans appear to be working correctly and work harder as the engine gets hotter. There does not appear to be any trace of coolant I the engine oil.

I have replaced the temperature sensor and thermostat.

Any ideas?

2 thoughts on “Car overheats then returns to normal”

  1. This sounds like the radiator may have had an air pocket and needs the coolant topped off. Also may need to replace the radiator cap as the system needs to be able to build pressure.

    Worse cause would be a blown head gasket but you would notice a loss of coolant in the radiator.

  2. Thanks Kristen,

    Tried your suggestions but problem persisted.

    It’s fixed now though. Turns out the inlet/outlet reservoir on the side of the radiator is supposed to have a divider in it which I presume is to divert the incoming water into the radiator fins and then when the water cycles back from returning at the other end it forces the water to go out the outlet pipe rather than back around the radiator. Well, this was missing so water/coolant coming into the radiator could simply go straight back out the outlet without going through the fins.

    This raises questions as to where it went because it didn’t even look corroded. It was simply gone. Anyway, this is Mexico! And at least we have a new thermostat and temp sensor and a compression test has revealed all is good there.

    Phew! And thanks for your help!

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