I work in a place that makes massive radiators and also repairs/services them and intercoolers. When we test them if there are any leaks we get them welded up. Then we test them again etc. Sounds like they stuffed up yours mate and I would send it back and get one that doesn't leak. P.s. I just bought a 600x300x100 (core size) intercooler from ebay. Only $240 to the door and doesn't even get hot . No leaks either