After replacing my Thermostat (The leak that used to be in the rear of the car under the Thermostat however is fixed!), cross-over pipes, water pump, and all hoses, I did a dry pressure check before coolant and it held ok with a loss of 5psi over 1 hour. So some small loss of pressure. However, it held coolant fine including a warmup and bleed. So I decided to do a pressure check with coolant in. At 10 psi a huge leak sprung I believe under or around the expansion tank and I believe the bottom piece popped out. I put it back, and tried only 5 psi and it seemed to hold for over an hour.

However on a 45 min long drive in Texas 106 degrees yesterday, I lost about 1/3 of my expansion tank extra volume. Basically I had it filled half-way and after 45 miles there and back, it is now at the minimum level. I can see spray residue below the tank on the hoses and then some at the bottom.
Was in the common failure there? Is it the fitting? Or is it the tank?
Really the o


nly thing left is the tank/tank fitting and the turbo aux pump. I overhauled the rest of the coolant system. I feel like somehow I may have caused this issue pressure checking at the tank and blowing out the bottom and damaging it? Is this possible?

 

Are you sure its leaking? It may have used that extra in the system. Even after bleeding the system it may use a little extra out of the reservoir. I see your pics, but unless it was squirting out when you stopped I don't think you have a leak. Did it leave a puddle underneath the car after you got home?