Cummins isx motor uses 1 gal.of antifreeze a day

Have you heater system checked? My truck had coolant leaking heating core under bed.

 

Simple things first. Test your rad cap.

 

Check the transmission. I had a trans cooler leak and lost around a gallon a MONTH. If it’s going in the transmission, the trans will eventually start leaking thru the seals.

 

If your truck has EGR then check the EGR cooler for an internal leak into the exhaust stream.

 

Charge Air Cooler , Especially if you lose coolant when truck is off more,like overnight. When you start truck in the morning and showing you low coolant,no leaks.

 

Explain to me how a CAC with no coolant to it near it or through it causes coolant loss without a high temp warning and a boiling over situation.

pull exhaust off back of turbo whether it’s a Volkswagen Beetle or a C18 CAT and anything in between with a turbo. If it’s burning coolant thru a cylinder it’s gonna have little grains of sand the color of your coolant in back of the turbo. Just to say it a blown head gasket doesn’t guarantee coolant in oil. If compression is blowing past fire ring into coolant passage that does not guarantee coolant running into a cylinder when shut down. What it does guarantee is little black flakes of combustion gas or carbon to be floating in coolant when shut down looks a lot like pepper. Precoolers, EGR coolers etc can charge cooling system with manifold pressure and still not put much coolant if any into cylinders. However that leak is always easily visible if you know where and what to look for. Any leak going past the cylinder liner o rings into pan is gonna show up in the bottom of blowby tube with a bright flash light…. It’s gonna be drops of coolant as in what ever color you’re running. As well as a steam like blow by that smells like coolant. This happens way before your coolant gets milky or even enough coolant to separate in bottom of pan after sitting an extended period and cracking the plug. Cold water leaks this time of year make you wanna #### in your hand and wipe it in your hair. Bottle test on a cold engine are not reliable. It needs to warm up and run through 2 fan cycles from engine temp as well as have the correct pressure radiator cap that’s verified to be good prior to putting the bottle on it.

A dart thrown blindfolded isn’t good enough on a 1000 dollar part. An educated guess isn’t either. A hands on diagnosis seeing it, touching it feeling it is. I’m not trying to tell the OP what’s wrong. Only how to find it. Just cause a piece has x miles in it doesn’t make a new one better.

 

I am going through the same thing and it put me out of business until i can put more momey together.. I found mine was burning it when I pulled the exhaust manifold off and 3 exhaust ports are wet with coolant.. and the valve stems are nice and shiny like they are being steamed cleaned.. it doesn't take but about 3 hours to tear down that side of the engine and pull the manifold