@gerjon2005 Before you shim that tank higher, check for contact between the cap and the top of the motor box. I've seen four 200s with this system and they all leak coolant. It drove me crazy trying to find leaks at connections/heaters/etc without success. Someone recently noticed on one boat that the cap contacts the top of the motor box and shimmed the new one down. I looked at another boat this weekend while changing the oil and I see all three things: coolant in the bilge, a cracked reservoir right at the seam, and a witness mark of the cap in the foam on top/inside of the motor box. I'm thinking that contact would be the cause of the cracking/leaks not necessarily the manifold temperature.