Coolant boiling problem

overheating? has many causes., if IS?
yes with A/C ON sure.
sure going fast the radiator cools better (higher gears)
OVERHEATING SIGNS ARE WHAT;
BOIL OVER? OR JUST DASH GAUGE TOo HIGH?
coolant leaks to ground or to front passengers toes?
5 year old hemostat should be good
fans kick on , at rear of radiator or are they dead?
off hand blind and deaf, the fans failing, on this 2017 car.
check fuses yet?
scan the PCm for fan errors or?
more causes
1: dead bugs plastered to radiator or front AC condenser. (back blast it with water hose nozzle)
new RAD do check condenser, same fix, cleaned.
2; belt slipping to water pump.
3: water pump impeller rusted to 1/2 its normal size
4; fans fail.

How hot does the engine get in degrees F? If it is boiling the coolant is overheating. Does the radiator fan work? Check the thermostat, check coolant flow through the radiator. Could be head gasket issue? Sometimes air in the system can cause problems? Just my opinion.

replace fan switch. depending what make vehicle, it could be located
on the side of radiator, on thermostat housing, on cylinder head.

replace thermostat.then bleed coolant system, this is how you do it.fill the cooling coolant system with 50 / 50 dexcool and water to raise boiling point,straight water will evaporate boil away cause engine to overheat catch fire thats why you need 50 / 50 mixture antifreeze and water.to bleed coolant system first fill coolant system until coolant stay at the full cold mark on the the coolant overflow jug,then you start engine allow it to idle,place the heater and ac control in any ac setting except max and the temperature control to the highest setting,run engine until lower hose to water pump is hot. with the engine hot run the engine speed up to 3000 rpm and allow it return to idle, repeat this 5 times. slowly open the bleed valve on the thermostat housing or look for bleed valve at the water pump heater hose.open bleed valve for 15 seconds to expel any trapped air.then top off the coolant as necessary,and when top radiator hose hot thermostat open up.keep adding cooling to overflow until coolant level stop at full cold mark dont over fill coolant.if engine seem like overheating while looking at cooling gauge turn off engine wait a while until cool off add more coolant until coolant level stay stable and dont drop any.when open radiator overflow cap use large rag over the radiator cap to keep from getting scald open radiator cap a little at a time but dont open radiator cap until engine cool down first.replace the radiator overflow cap, thermostat,and engine coolant temperature sensor and check the cooling fans fuses and relays see what happens.

Hi Odnanref, If the coolant is boiling you have a problem with the cooling system. If you cannot see a leakage have the thermostat in the engine checked and replaced and hope that you have not overheated the engine to the extent of needing a cylinder head reconditioning job carried out. The AC is effected because the condenser is mounted in front of the radiator and depends on cooling from the fan. If the engine overheats the AC will be unable to cool. Regards John

Answer could be a faulty thermostat,or it could be a sign that your head gasket is about to blow ,or last of all your timing could be out of sync.

Answer 2 from Inventus: It means your cooling system is funtioning properly. In a system having a coolant recovery tank, coolant in the radiator is always up to the brim, hot or cold. There is negligible or no air space. When coolant in the radiator expands sufficiently due to warming from the engine, it will squeeze past the pressure cap's bottom seal and flow into the recovery tank. (If no provision for such expansion was present, the expansion would rupture the radiator or your hoses.) Only coolant within the radiator is under pressure, and because of this pressure (together with the elevated boiling point that the "anti-freeze" permits), it normally does not boil. But once past the pressure cap's bottom seal, the overflow is at atmospheric pressure and therefore boils.
This boiling is usually unnoticed after a short, i.e., local, trip because the cooler coolant already in the recovery tank quenches it. But after some highway driving the influx of more hot overflow heats up all the coolant in the recovery tank to the (unpressurized, i.e., "natural") boiling point.
As the engine cools when shut off, the contracting coolant in the radiator sucks back coolant from the recovery tank. Fluid in the recovery tank should never be below the "full hot" or "full cold" marks, lest air be sucked in.
-- BETTER ANSWER ==
Your cooling fans are not turning on. It is not normal for your overflow tank to boil like that. It is true that your radiator is overflowing into the reserve tank, but that means yourr adiaotor is boiling. Check for blown fuses or relays for your cooling fans. IF theya re fine. run your engine for about 15 minutes and drive. When you temp level is at normal operating temp open your hood with the engine runing and see if your fans are on. If they are, then you may have a bad thermostat or a plugged radiator, or a bad water pump. If the fans are not on, get your cooling fan switch replaced if your car has one. Check your temp sending sensor

When sitting still, yes both fans on a car equipped with two fans will run. The temperature ranges you posted seem within acceptable range. That said, the water (coolant) should not boil at those high temperatures, but some overflow is expected/normal. Ensure that you are not adding pure water to the radiator and instead are premixing it with antifreeze coolant or adding premixed 50/50 that you can buy at auto stores as this will keep the water from boiling and freezing.

As an added point of information, the hose leading into the overflow jug is two-way, meaning that when the coolant in the radiator cools down enough, it creates a vacuum and pulls coolant back into the radiator.

Zach

The coolant temp sensor tells the computer tempurature of engine at all times.It tells the coolant fans to come on,and also very important,when to cut off.If the fans don`t go off by them selfs,then temp is not going down.Now this is if the ac is off,cooling fans come on any time ac is turned on,so check for fans coming on and off with ac off.A bad coolant sensor would cause the fans not ot come on,but not to cut off nessasaralyCoolant systems must be bled of air trapped in systemfor the engine to be cooled .If air is in the system,the coolant won`t flow correctly.

You would need to check out the different cooling components. The radiator cap, thermostat, fan for radiator (car should run at 195 degrees), is anything blocking the face of the radiator, are any of the cooling hoses kinked or collapsed, is the water pump circulating the coolant, is thw belt still on the water pump?

check to see if electric fans turn on in front of radiator