Thanks in advance. 454xl I replaced 1 of the endcaps and its cupped compared to the original flat cap. Is the cap supposed to seal against the inner veins with the gasket? Over the course of 3 years the engine is running hot and Im having a hard time solving it. New thermostat, raw water pump u cooler, risers and manifolds, circ pump and both motors rebuilt 2 years ago. I have the same amount of water flow out the back of the boat on both engines. The water temps going out are 165. The gulf temp is 92. The only difference is the exhaust air on my hot engine is way hotter than the exhaust on my normal temp engine, to the point I cant hold the exhaust flap open with my hand. That engine seems to steam more than the other engine. I cant figure out the raw water flow thru the heat exchanger? It looks like with the cupped cap the inlet water would bypass the heat exchanger and go right to the elbow and go out? The heat exchanger has 4 chambers Thanks for any help