Jim Weston

I have a 2000 Checkmate with 7.4 MPI 310 HP (not MAG) with 230 hours. The water intake on the Bravo 1 is on the front of the outdrive and relatively near the bottom. How would I check to see if there is a blockage in the block caused by sand as the boat went through a sandy bar recently and I thought the sand was flushed out by the mechanic at the marina. I also opened all the hoses and there are no block hoses or oil cooler. Water comes out through the holes used for winterizing. The impeller and its housing were the first item to be changed after the sand bar was encountered. Good flow out the exhaust at transom. There is less flow through the starboard exhaust than the port side. I measured, but not very scientifically, and calculated 6.5 gal./minute on starboard side at idle - 8 gal./minute out the port side. Temperature went to 170 on drive with cold city water in 20 minutes but went no higher. Only the starboard riser gets very hot - can not keep a hand on it. New 160 thermostat also. On inland lakes the temp. goes a little over 180 at cruise speed and WOT. Temp. goes back to 170 after the throttle is pulled back. Some steam on starboard but not major amounts. Do I have a problem or am I concerned about nothing? Should I just drive it at a little over 180 and enjoy? Thank you JW

blue thunder

You should be able to lay your face on the riser, it should be that cool. You should remove the riser that is getting hot and see if it is clogged with rust and scale. If so, you can soak it in muratic acid to clean out the rust.