# Coolant leak?



## FM3 (Aug 12, 2019)

If you don't see a leak, it might be worse and be burning it. First thing I'd do is check the oil and hope it doesn't look like a milkshake.

If you're losing that much, of course stop driving it until you figure it out.

There's only so many radiator hoses and heater hoses to check. The coolant has to be going somewhere.


----------



## DexterII (Jul 14, 2010)

Agreed; if you don't see it on the ground it could very well be an internal leak. But, given the fog through the vents, the first thing I would do is feel along the front of the carpet on the passenger side, pull it back a some if you can and feel the padding under it as well, because you might have a leak in the heater core. I would also inspect the back side of the water pump for any tell tale signs of a bad seal. You generally won't see coolant standing there but can sometimes see something telling like discoloration or trails. Coolant leaks can sometimes be hard to track down because they'll come and go for a while before something really goes south.


----------



## ukrkoz (Dec 31, 2010)

Fog outta AC vents with AC working in humid climate is simple condensate. Fog indeed.


----------



## farmerjohn1324 (Jul 28, 2015)

ukrkoz said:


> Fog outta AC vents with AC working in humid climate is simple condensate. Fog indeed.


This fog started right after the coolant was filled up after being low for a long time.


----------



## HotRodx10 (Aug 24, 2017)

Check the spark plugs - if they're white, you're burning it. 



If not, check the weep hole on the bottom of the water pump while it's running and after you stop it when it's been up to operating temp. Sometimes the water pumps seals only leak when they're running and sometimes only after the engine is off, but the system is still pressurized.


The other thing to check (or replace) is the radiator cap. If it's not holding pressure, the coolant will boil out, many times leaving no trace, or at least no puddles.


----------



## ron45 (Feb 25, 2014)

Most of the time the leak is or around the heater core

Most heater cores are located on the firewall of the passenger side and a good indication its leaking would be the carpet is wet.

But.......


----------



## huesmann (Aug 18, 2011)

Fog through the vents is one thing. If your windshield is hazing up, that's a leaky heater core.


----------



## HotRodx10 (Aug 24, 2017)

If a coolant leak is fogging the inside of the windshield, you should be able to readily smell the coolant inside the vehicle.


If the coolant is being burned in the engine, the exhaust will usually have a sort of sweet smell to it.


----------



## ukrkoz (Dec 31, 2010)

The ONLY time I had fog outta vents - there is no such thing as AC vents, just vents - was in humid TN summer. Scared the **** out of me, I thought car is on fire. Then, I got used to it. It kept doing it every time when it was muggy outside.
There is no connection between freon circle and coolant circle. 

Maybe, just maybe, it is leaking somewhere onto the exhaust, in engine bay, right next to the firewall, vapor goes up and is being sucked inside through cowl vents. But I REALLY doubt that as you'd have noticed coolant specific smell.


----------



## ron45 (Feb 25, 2014)

If your vehicle has the quick release lines to the radiator.?

Had to replace the radiator on the 2012 Silverado 2500HD

The leak was at the bottom radiator quick disconnect line, drove me nuts finding it. Was hidden behind everything.

In this video it shows a type of quick disconnect.


----------



## raylo32 (Nov 25, 2006)

This literally could be just about anything but heater core sounds like a likely culprit. You can rent a test kit at the parts store to pressurize the system while it is cold and look for leaks. I'd start there.


----------



## HotRodx10 (Aug 24, 2017)

> This literally could be just about anything but heater core sounds like a likely culprit.



There are alot of possibilities, but a leaky heater core will make the inside of the vehicle smell like coolant with the heat on, especially with the coolant level low, once the system gets up to temperature.


With no signs of obvious external leaks, and if the OP doesn't find indications of coolant being burned or getting in the engine oil, my best guess would be a radiator cap that's not holding adequate pressure. A weak radiator cap (which is fairly common) generally leaves little observable evidence of where the coolant went, since it spews out mostly vaporized coolant only while the engine is hot, which is usually while you're driving.


----------



## huesmann (Aug 18, 2011)

OP may not know what to smell for.


----------



## HotRodx10 (Aug 24, 2017)

> OP may not know what to smell for.



That's easy to fix - open a jug of the stuff or the radiator cap and take a whiff. It's a pretty distinctive smell, anyway; way different than anything a person normally smells in a car. Should be fairly obvious, especially if it's vaporizing (appearing as fog out of the vents).


----------

