I'm looking for help with an 86 Force 50 regarding cooling flow. It has been run mostly in salt water but always flushed with fresh when arriving home (always back on trailer at end of day). I pulled the thermostat out and it was full of crud and well worn so I got a new one. The passages into the heads look clear as far as I can see, but when I pump water up from the bottom there is barely any flow. The passage that comes off the thermostat housing and attaches to the exhaust port cover via hose was completely blocked with salt/crud. I cleaned the thermostat housing and the passage into the exhaust port cover (several inches deep), but I can't seem to get past that point with flow. Where should that flow go? Is there a way to clean the crud out of both the engine and exhaust port cover without taking the heads off and/or removing the exhaust port cover? I'm looking for recommendations on what to flush with or the best way to clean both items. I've read that vinegar cleans salt deposits but I'm not sure if I should use it, at what strength, and is it ok to put it in and leave it for a period of time. Would one of the commercial products be more effective? I'm retired and on a thin budget so any economical solutions will be greatly appreciated.Thanks in advance for any help.