I can not see any through the brown clear line with a flash light behind it. Odd that when the car sits for a couple hours it start perfect runs for maybe 45 seconds great then smokes and baubles observed in the return. I'm thinking some how maybe in the filter the air escapes runs ok then air is sucked in but puzzling as that's a low pressure system. My newest thought just now will be to chase the suction side back to the tank. But I have not seen any leaks anywhere this has me stumped for sure.