My freshwater Catalina 27 began overheating after owning it for a year. I replaced the impeller, which had lost part od several vanes. It was still overheating after replacement. I then flushed the system out with a garden hose and spray nozzle with the thermo stat in place. There didn't appear to be any major blockages. I also closed off the seacock on the supply and witnessed water coming out of the exhaust. I then removed the thermostat and noted some small "bb" sized pieces of rubber in the seat of the thermostat. I removed the particles and flushed again, and back-flushed as well with the thermostat in place, and with the seacock both open and closed. My pump pressure is fine, there are no obstructions except that I suspect that the thermostat is not able to fully close, so I have ordered a new thermostat. Can I crimp the return line to force the pump to use lake water for cooling as a temporary measure until my new thermostat arrives? I have seen this on several posts. This is a raw water system, used on a lake, with a 140 degree thermostat.
Universal 5411 Overheating
- Thread starter Blwarch
- Start date
Thanks. What if I leave the T-stat in as the gasket is getting tired from removal and flushing. Can I just crimp the return hose?
If memory serves the engine recirculates the lake water till the thermostat opens and draws in cool lake water so leaving the thermostat out will just make the engine draw water from the lake and never get it up to temp. Not a big issue but you may notice some exhaust smoke from a "cold" engine that you do not normally see.
Temporary solution
I removed the thermostat and clamped off the return line with some needle nose vice grips. After monitoring the temperature gauge, I had to make a slight adjustment to get the flow correct. The engine ran about 10 degrees cooler than specifications (130). Had a great sail and look forward to getting my parts in to complete this the proper way. Thanks for your comments.
I removed the thermostat and clamped off the return line with some needle nose vice grips. After monitoring the temperature gauge, I had to make a slight adjustment to get the flow correct. The engine ran about 10 degrees cooler than specifications (130). Had a great sail and look forward to getting my parts in to complete this the proper way. Thanks for your comments.
The thermostat actually closes when the proper temperature is reached at 140 degrees. This makes the water pump take fresh cool lake water go through the engine and out the exhaust.