So. I know our rugs temp gauges are crap. Ive used my Ethos OBD snap on scanner and the temp never exceeds 216 F. It runs cool at idle and warm (per gauge) driving. When I kill it the coolant is bubbling back into the overflow. Mine is a 2007. My dad has a 2008. Both L5 motors. Both having the same issue. Radiator, water pump, fan clutch and thermostat all changed recently. Still bubbles. I’m at a loss. Any help guys ???

 

You are in AZ, and just figured out what is called ....... "normal."

Here is cut & paste from an OLD Thread on coolant 101 in response to those freaking out about seeing 3/4 on the idiot gauge. ...

"First, 3/4 mark temps are not overheating to begin with. Overheating is when the needle is in the red.

1) When your motor is running your water pump is turning and circulating coolant through the radiator and motor, passed the temp sensor which is reading the temp of the coolant exiting the motor at the head. The radiator cools the fluid from the motor by air heat exchange cycles through the motor which heats it. This is a continuous cooling cycle.

2) When you shut off the motor, what happens? The water pump stops and so does coolant circulation. Hence, the sensor is now in coolant within the head that is not moving and experiencing a rapid climb in temp because it is direct contact with the motor/head and not being flushed with cooler fluid from the radiator. The cooling cycle has stopped. You turn the key on a few moments later and what do you see? Higher temp than when you shut it off because of "heat soak." It may bubble into the expansion tank while sitting for a while.

Start the motor and and that starts the cooling cycle, go back to #1. The temp decreases after a few minutes.

So what you have observed is completely normal for every water cooled automobile.

Get a scan gauge or borrow one. The dash temp gauges are not highly accurate so you have only an idea of what the actual temp is, and for most applications that is all the operator needs. It is almost like an idiot light with a moving needle. BTW your DIC will display "ENG HOT" when your H3 starts to overheat. If you had the AC on when it begins to overheat, the AC will shut off before the temp triggers the DIC display.

The actual temp at the 3/4 mark is about 212-218F depending on your particular truck's gauge accuracy, plenty of room before an overheat. When I turn my 3 off and the actual temp is say 190F (1/2 on the dash gauge), in about 10 seconds if I turn the key to on, it will read 204F. All of which doesn't matter because with the engine off, everything is beginning to slowly cool, no more heat is being made.

FYI: 50/50 water and Dex-Cool has an open boiling point of 228F (in an open pot, no pressure) and in a pressurized cooling system @ 15PSI, 265F."

 

I’m in Arkansas. Common mistake. Lol. I know the gauge is dumb and incorrect. I verified that with my Ethos. My concern is the boiling. Maybe I need to drain and refill with the recommended 50/50 dexcool solution to remedy that problem. Honestly I never knew the coolant increased boiling point. Learned something today. I’m currently running straight water due to the possibility of needing to go back into the system and not wanting to lose costly Dexcool. I’ll give it a go and see what happens. Thanks brother !

 

OK, straight water is your problem, coolant is 50% distilled water 50% Dex-Cool. I usually just by the premixed 50/50 just because it can't get screwed up.

Sorry about the AZ, my eyes can see the AR now that you pointed it out to an old blind guy.

I bought my 09 Alpha Off Road out of AR couple years back, no rust!

 

X2^

 

@hummerz Yeah Yeah Yeah 😂 I’m a dumbass.

 

a bad radiator cap will also make it boil sooner. boiling temp goes higher under 16psi of pressure that the cap holds.