Frontier heat blows cold at idle

[calicamper]

If it turns into a common refill. Pickup a new oem radiator cap. The parts store generic caps are junk avoid them.

 

[gtbensley]

Learn your cooling system. That is NOT an overflow bottle. It is a degas bottle. It is pressurized and a part of the coolant flow. These truck do not have an overflow bottle. While running there is a steady flow of coolant (and air bubbles if any) off the top of the radiator. Removing the radiator cap makes for a huge air bubble that the system has to work to get out. If you noticed the radiator cap is just that, a cap. There is no pressure rating and nothing to block the flow out of the top of the radiator to the degas bottle. It is a bit hidden but on the bottom of the degas bottle there is a hose going back to the engine. This is where the coolant free from air bubbles returns to the engine. If the degas bottle is not maintained with enough coolant the engine will suck air in. And you get the air lock that takes out the heat at idle. So on this cooling system you do NOT remove the radiator cap to check or top off the coolant, it is done through the degas bottle.

I stand by my comment, while it is a degas bottle, its filled to the correct line and still blows cool at times.

 

[Airmapper]

Hardly maintenance there bub. My coolant and all fluids get checked often and replaced when needed. Overfilling the overflow while the radiator is full is not maintenance.

Agreed, if I had not heard from others a little extra coolant solves the problem, I would have had no reason to add coolant when it reads full.

I mean we are talking an inch, more likely less over the line to make it happy. But to suggest that someone is neglecting maintenance in this instance is just ignorance of the quirks of a Xterra / Frontier. It's already been stated in the thread before, so either someone didn't read or just wants to put down someone else.

 

[broncobowsher]

The MIN mark is where it starts sucking air. It shows in the normal because there is an air bubble taking place of where some coolant should be at. If you really got the air bubble out then it would show low. The min mark isn't good enough. If it ever drops to MIN, you are sucking air.

 

[gtbensley]

The MIN mark is where it starts sucking air. It shows in the normal because there is an air bubble taking place of where some coolant should be at. If you really got the air bubble out then it would show low. The min mark isn't good enough. If it ever drops to MIN, you are sucking air.

Valid point, fair enough. Either way I ended up adding just a little bit to bring the indicated level up some. So far so good.