What can cause a coolant leak?

[NDSpeed]

I’ve done the Cummins R2.8l swap.

so an entire new coolant system has been put in. I’ve done a new heater core to because I had coolant on the floor board.

now anytime I run the Jeep, it drops some coolant from the overflow line. Not much. Drips really.
The radiator is never fully topped off. It always sits about an inch from the filler neck.

this truely has me lost.

 

[NDSpeed]

I’ve also installed a new cap because the one that came in the axis kit was loose fitting and I could squeeze coolant out the cap by squeezing the upper hose.

 

[Chris]

Sounds like it's leaking. Without being captain obvious, have you looked for leaks or used UV dye to inspect for them?

 

[Alex01]

I’ve done the Cummins R2.8l swap.

so an entire new coolant system has been put in. I’ve done a new heater core to because I had coolant on the floor board.

now anytime I run the Jeep, it drops some coolant from the overflow line. Not much. Drips really.
The radiator is never fully topped off. It always sits about an inch from the filler neck.

this truely has me lost.

Do you have an overflow bottle attached to the overflow? My understanding is when the engine heats up the coolant will expand and go into the tank. As it cools down the fluid should get sucked back in.

 

[J R]

Are you referring to the vent on the over flow bottle dripping?

If that is the case I would be looking for compression in the cooling system.

 

[NDSpeed]

I’ll have to clean it up. There is coolant on both caps. Looks like Nothing from the overflow line.

I’ll clean it all up and re-look.

 

[NDSpeed]

Just came home for lunch. Took a photo. I’ll have to clean it up. Looks like coolant from both caps are around the seams.

 

[NDSpeed]

So the Cummins swap guys on Facebook said the expansion tank is too small. To get rid of the pretty TIG welded pint size can and install 1.5 Qt generic rig from Amazon.