Originally Posted by
cadunkle
Replace the water pump. If you can't source a marine pump go ahead to your local parts store and get whatever SBC water pump they have on the shelf, likely for a Chevy pickup. Check pulley flange mounting position is the same ralative to the block. Replace with a marine at the end of the season. Marine pumps have a few differences such as impeller and backing plate that resist corrosion. It's possible the impeller on yours has rusted apart and a piece broken off to seize the pump.
Measure depth of pulley and diameter, find one at a junkyard, ebay, amazon, rockauto, etc.
SkiDIM is probably your best bet to get the right marine parts quickly, if they can get them to you quickly enough. Just offering an alternative if you can't source marine parts quickly.
Except that all but one year of the true Comp had a small block Ford engine as a power plant in it I thought.
'86 Comp TS6M - Reborn 2016
Riding a HO Sports CX Ski