I have a rebuilt chevrolet 350, volvo penta AQ280 in a 25' fiberglass boat. I had the left side of the motor (on land facing the back of the boat) clog over the weekend on the lake and the temp jumped up to over 200? pretty quickly. Impeller is good, new water pump and it is getting plenty of water out of the thermostat housing. I disassembled the exhaust riser elbow (Osco mfg# 56879) on the left side and there was a good amount of rust flakes. The exhaust manifold looks pretty clean. Should I change the riser elbow or both manifold and riser? Also I noticed the gasket between the elbow and manifold was covering the long slots at the top and bottom of the elbow base. Is this correct? Or should holes be there also? I found a stainless gasket but it also covers these holes with only a tiny hole in its place . And finally if anyone knows the ft. lbs of torque I need to apply to the 4 bolts holding the elbow to the manifold. Thanks for any help you can provide!
