I put a new 13lb cap in and it seems to be dumping water into my catch can way too easily. I can't seem to recall what rating I had before. What can I expect should I put a 15lb cap on there? The car is NOT overheating... it just keeps dumping more water into my can. It's NOT set up for recovery however... so the water is not returning to the radiator during cool down. I thought that maybe the car needed to find it's happy level of water in the radiator.... but when looking in the cap... the water is not above the top row of fins.... this can't be correct. The thermostat was replaced last summer... and I believe is working properly. When heating the car up with the cap off... you can see the water go from stand still to be agitated when it reaches the 185 degree level. I just feel like I'm chasing my tail on this. I did add a small drill hole in the top of the catch can to release the ton of pressure I was building (causing me to blow a radiator hose). That seems to be working better now. I've had a ton of suggestions... most of them contradicting each other.... but I guess I'm open for more!!!