overheating dilemma

[shore]

last summer my universal 5411 (raw water intake, with no filter in line) began overheating without producing discharge. i checked the thermostat, and pump, and it was working fine. after a few start ups, overheating, and letting the engine cool, it would eventually run normally (operating temperature 150 and have routine water discharge). anybody have any ideas about what might be going on, and how this can be repaired?

 

[David Hirtle]

I had such a beast for twelve years. Does your engine have the "mixing valve" that is located just above the intake? IF so, play with that so that it appears that you are "closing off the flow" a little bit. At any rate, your engine should run no hotter than 145 degrees.If your impeller is good, you possible could have an air leak in the sustem. Check the water system to ensure that nothing is leaking anywhere. By "reving" the engine a little, sometimes the airlock will clear itself. The only other suggestion that I might offer is that depending on the age of your engine, you clould have some rust that is obstructing the flow through the water jacket....remember, it's "raw water cooled" and water and iron have an adverse reaction. Check with you regular mechanic if it happens again. Good luck!

 

[Larry W.]

Hot 5411

Shore; I had one for five years. It began to overheat sporadically so I checked everything. The thermostat appeared to operate normally, (heated it in a pan of water on the stove)but I changed it anyway and the problem stopped. FWIW, I had a dock neighbor who put his raw water intake hose into a bucket containing a very strong vinegar solution. When it began to come out the discharge, he shut it down and let it sit overnight, then flushed it. A lot of gunk came out the discharge.