I am replacing the thermostat in my 1996 Four Winns 240 Horizon with a Volvo Penta 5.8FI (Ford) that is pretty really an OMC Cobra 58FAPHUE 1995 model system. WONDERFUL boat overall; just a leeeettlle short on horsepower. The end of last year on the last several outings when river water temps began falling the engine began to run really cool (120-130 deg F). If allowed to sit for a while after running (i.e.warm soak) the heat would cause the guage to go up into the middle of the normal range and go back low in less than a minute after starting. No big deal. Thermostat stuck open - right? I am a 40 year boater having done much of my non specialty repairs and maint for all of that time - get to it next spring. Anyway I never got around to changing the stat.
Put her in for a outing last weekend. Ran great for 3 days with the same low temp condition. THEN suddenly on one outing after sitting hot for about 1/2 hour BAM overheating. Stat stuck closed now? Likely. No time to investigate had to pull the boat.
Pulled the stat today. Really had to work it, bend it to get it out. Tested both the old and the new stat in boiling watter and they BOTH opened. I guess that if the old stat had been stuck closed that all of the abuse in removal could have broken it free. Anyway new stat is a Sierra 18-3677 160 deg F replacement for the original VP/OMC P/N that I was told was no longer available. Old stat had a small V notch in the valve I assume to allow for quick blow off of any air in the block; the new Sierra does not have this V. Any thoughts on the Notch/no No notch?
I have re-assembled things and will put her in the water this weekend if the river level cooperates and we will find out where we stand.
Any thoughts on any other problem(s) possibly causing the ow temp/overheating here? I know that 1st owner had the water pump rebuilt by the shortly before I bought the boat (Summer of 2008) It just seems TOO co-incidental about the low - high temp swing. I can't see anything but a stat causing a low temp condition like this.
John
Put her in for a outing last weekend. Ran great for 3 days with the same low temp condition. THEN suddenly on one outing after sitting hot for about 1/2 hour BAM overheating. Stat stuck closed now? Likely. No time to investigate had to pull the boat.
Pulled the stat today. Really had to work it, bend it to get it out. Tested both the old and the new stat in boiling watter and they BOTH opened. I guess that if the old stat had been stuck closed that all of the abuse in removal could have broken it free. Anyway new stat is a Sierra 18-3677 160 deg F replacement for the original VP/OMC P/N that I was told was no longer available. Old stat had a small V notch in the valve I assume to allow for quick blow off of any air in the block; the new Sierra does not have this V. Any thoughts on the Notch/no No notch?
I have re-assembled things and will put her in the water this weekend if the river level cooperates and we will find out where we stand.
Any thoughts on any other problem(s) possibly causing the ow temp/overheating here? I know that 1st owner had the water pump rebuilt by the shortly before I bought the boat (Summer of 2008) It just seems TOO co-incidental about the low - high temp swing. I can't see anything but a stat causing a low temp condition like this.
John