Coolant loss no extenal leaks

So I topped the coolant off Friday evening. It has sit over the weekend and it’s leaked down about an inch and a half. No signs of leaks no wetness anywhere.
No smoke from exhaust when fired up.
Oil still looks normal.
I’m getting no pressure back through the reservoir when running. “I used my hand as I don’t have a pressure tester”
Ima check fuel this evening for any signs of coolant.

 

I was losing coolant, it was going inside the transmission. The trans cooler sprung a leak. I bypass it. Regardless, I ended up rebuilding the transmission a year later, the coolant ate up the lining on the synchros.

 

Aight so I’m gaining coolant while the APU is running??
Been working on the inside of my truck for a few fours and letting the APU run. During this time it has went from and inch and half below cold coolant line to way over full.
Any ideas??

 

Performed a pressure test and found a leak on top of the radiator where the small line that runs from from the side of expansion tank to top of radiator. My question would this small leak be enough to loose a gallon a week?

 

Well I'm thinking if that's the only leak you found then yes.

 

Yes

 

Leaks a lot more when you drive.

 

We’ll I’m hopeful that was the problem.
I replaced the fitting, pressurized the system and no loss of pressure (for 2hours)
Let sit overnight to see if any additional leaks, none spotted.
Started the truck with pressure gauge and let run for 5 mins and it built zero pressure.
Ima head back out this evening for the week and keep my fingers crossed!

 

Good deal.

 

You might want to pull the drain plug out of your transmission and see if you find your lost coolant in there.