6.2L Coolant Temperature

[Truckzor]

Anybody who has an idea why my reservoir anti-freeze level goes down without evidence of a leak please contribute your wisdom. (No, there isn't anti-freeze in the motor oil. I just changed the oil and after 1,200 miles it looks clear and new.)

Mine is doing this occasionally, too. Definitely not going in the motor and I've never seen a drip in the garage.

 

[cjf1001]

After some spirited driving in manual mode, I came home and parked in the driveway. Came back out later and had coolant bubbling out of the reserve tank out of the cap. If you look there are 3 small holes in the cap. No warning lights, did not get hot (according to gauge). I have tried several times to recreate the problem and have not had it reoccur since.

 

[Ruger]

@bigrig, the coolant flush was last year. All possible air in the system has long since been purged.

@Truckzor and @cjf1001, I double-checked this morning after the truck had completely cooled overnight. Coolant level in the reservoir was down about 4 or 5 ounces - less than a full 8 ounce cup. I checked everywhere for signs of leakage. The top and sides of the reservoir, the area around the radiator cap, the sides of the radiator, the hoses, the frame rail under the radiator, the front of the engine, the skid pans, the area around the thermostat housing - everything is bone dry. No sign of leakage anywhere. No puddle under the truck. Pulled the dipstick (of course) and the motor oil (which I had changed just before leaving on the trip) is clear, bright in color, and at the proper level. I'm not losing coolant into the crankcase via a leak in a head gasket.

So are mischievous aliens abducting my anti-freeze? Really, where could it be going???

 

[downforce137]

Does that cold air kit use the factory reservoir bottle? I'd replace the radiator cap before messing around with anything else. It's possible that it's not holding pressure and leaking out on the ground, if the reservoir isn't over filled and dumping thru the overflow.

 

[Ruger]

@downforce137, the AIRAID CAI does use the factory reservoir. I installed the CAI at least 5 years ago and it has functioned without issue. The only time there was evidence of a problem with the reservoir cap was the one time I failed to snap it completely down tight.

Fluid level in the reservoir has been between the high and low cold fill marks throughout the vehicle's life, and again the only sign of leakage was the one time I failed to snap the reservoir cap down securely.

 

[cjf1001]

Does your reservoir cap have small holes where is says COOLANT. I think mine had very small holes in the "O"'s and "a" that was where my bubbling out of.

 

[Ruger]

Does your reservoir cap have small holes where is says COOLANT. I think mine had very small holes in the "O"'s and "a" that was where my bubbling out of.

Never noticed it before, but yes. I shone a flashlight through it and there are breather holes in the D of RADIATOR, one of the Os of Coolant, and the O of Only.

 

[MTF]

How level is the hose from the radiator to the overflow?
You don't want a big loop down anywhere.
And of course it's not pinched anywhere right?

I had to pull mine tight and route it around better and used two small zip ties to hold it up.
I did notice my radiator is full to the top now, I did that 5 years ago.

 

[Ruger]

How level is the hose from the radiator to the overflow?
You don't want a big loop down anywhere. And of course it's not pinched anywhere right?

I had to pull mine tight and route it around better and used two small zip ties to hold it up. I did notice my radiator is full to the top now, I did that 5 years ago.

NEW INFORMATION! Thank you @MTF!
The hose that links the radiator at the cap to the reservoir on my truck appears to dip downward as it goes around the airbox. It's always been this way, and apparently hasn't been an issue until now. But I'll go fix it! I had no idea that this might be an issue.

 

[MTF]

I don't Know if it's an issue pur say.
I only noticed the radiator is full to the point of some flowing out when I open the cap. (when the truck is cold of course)