northern
Well-Known Member
- Jan 17, 2007
- 3,526
- Boat Info
- 380 Aft Cabin 1989 Charts Timezero radar Furuno
- Engines
- Twin 454 strait shaft
We have twin 7.4. All was well until I changed the oil and transmission coolers on both engines. I got both main heat exchangers serviced. When I put it all back together the Starboard engine worked as before. The Port engine ran a low temperature at start. Gauge would not move then it would go to 200. and drop back to 170 then to 120 then to 200. The reservoir bottle would fill beyond full. I replaced the thermostat and things did not change. I bought a new main heat exchanger. The engine reads 120 then all at once it goes to 180 the reservoir does not over flow. The engine does not use antifreeze. If I speed up the engine temp will drop to 120 then go back to 180.
Any idea what is the cause of the temp fluctuation. I have used a heat gun and same components on both engines read the same all the time. I have aimed my temp gun at the top of the temperature gauged and it reeds as per the gauge on the dash.
Any idea what is the cause of the temp fluctuation. I have used a heat gun and same components on both engines read the same all the time. I have aimed my temp gun at the top of the temperature gauged and it reeds as per the gauge on the dash.