After five years of high-use operation I decided to change out the two thermostats on my 130 hp v4 looper. <br /><br />I have a temperature gage that up until now never rose above 120F, mostly 110F. <br /><br />With the new thermostat, p/n 436195, the temp rose above 140F at idle. I did not like what was happening and shut down.<br /><br />Replaced the old thermostat (other parts new) and the same thing happened. The temp rose above 140.<br /><br />Running without the thermostats the head is 110 at idle.<br /><br />Im puzzled. A read of prior posts would indicate that 140F is nominal.<br /><br />Does it mean that the thermostat has been running full open all this time?<br /><br />The assemly does not look conventional and I do not understand how it functions.<br /><br />The thermostat assembly sketch that I have does not show the orientation of the tapered spring. I am fairly sure that the large end of the spring goes toward the cover. Is that correct? <br /><br />I had removed the heads for inspection. The piston and cyl walls near perfect. Most of the original hone finish is still clearly evident. No build up in water wall, quite clean. The block mating surface that opposes the head is almost like new. The head had some pitting and was remachined. Always used regular gas and WalMart oil. The motor is used in saltwater exclusively. Never freswater flushed. The plug gap was widened by a season of use but otherwise the plugs were fairly clean.
