2.7L Coolant bubbling and overflowing reservoir

Hi guys,

Recently was at 11,000 ft, driving extensive hill climbs in 4LO, not loaded up. Proud of the 4 banger.

After stopping and cutting the engine, I heard bubbling from under the hood.

Here's a video:
https://photos.app.goo.gl/DCJXAgPnPNNQ1tWJA

Note engine is off!

I swapped the radiator, cap, and coolant last year. It seems like gasses are flowing from the cooling system back into the reservoir. On another climb the amount of coolant flowing out overflowed the reservoir and spilled on the ground.

Not having any overtemp situations, engine temp needle is planted firmly in the middle of the range.

Hm, now thinking its a head gasket. Why else would there be gases in the coolant system.

 

Anyone?

 

Did you allow the engine to run for a bit to cool off before your turned it off?

 

Coolant boils at a far lower temp at high altitudes plus the engine is working considerably harder. If you were not having issues at the altitudes you normally run it at it only pops up when you are at high altitudes, I wouldn't worry in the least, just make sure that the overflow has enough coolant in it to draw back into the radiator and check it when you are back down. Stop and eat somewhere and check it when you come out and add if needed.

 

I thought of this but of the 3 times it happened I did not let it run.

 

This is a relief. I should have run my obd2 sensor to get and accurate coolant temperature.

 

Thats probably why it's boiling, after working an engine very hard you should let it run for a few minutes so it can cool off, turning it off immediately stops coolant flow and can allow it to superheat & boil the coolant in the block if the engine has been ran hard and not allowed to cool off first.

 

Change /check the oil if its milky if your really worried about said head gasket ...

 

I drive in the mountains a lot. When heading up at high altitude, gear down and slow down. Turn the heater and/or defroster on with the fan on full. This can drop the engine temp by 5°F or more.

 

Can have a blown head gasket without oil in your coolant…..or even with passing the combustion gas detector

 

Why turn the defroster on? That only activates the AC compressor and puts more load on the engine.

 

BTW, My temperature gauge needle remained in the middle of the dial and never registered "hot" or "overheating". It heats up normally but never went super hot. Based on its location, drivers side, it could be that the coolant temp is registered on the into the engine side, and missed the hot, boiling coolant on the exit.
But if my coolant temp sensor didn't catch this boiling then will and OBDII sensor that reads that sensor for coolant temp have any hope of notifying me of an overtemp situation?

 

There's only one sensor, it reports to the ECM and the ECM sends the temp signal to the gauge.