nrowles wrote:So it was recommended to me on here to swap out the 160 thermostat for either a 180 or 192. I put a 192 in last weekend. Truck runs good and the temp floats between 190-200. Yesterday after shutdown I monitored the gauge and it crept up to 230. And it wasn't a hot day by any means. Cloudy and 80. Is this 230 too high after shutdown? It wasn't pressurizing out of the radiator.
When coolant stops moving it absorbs the heat in the engine. With electrical gauge you will not see this because it shuts down when the key is off.
Having said that, I doubt your gauge is reading accurate. a non pressurized system with 50/50 antifreeze and water will boil around 226 deg, at 230 you should see boiling. If just water is used 212 will boil in a non pressurized system. These are sea level pressures, the boil point goes down with altitude.
If coolant in the engine exceeds the thermostat setting it should open and coolant will slowly thermosyphon out the top of the engine to radiator and back through the bottom hose keeping the temp below boiling even with the engine not turning.
If you see a huge rise in temp when shut down, I would suspect poor heat transfer to the coolant in the block. IE the block has rust build up in the coolant side of the casting, preventing the coolant from doing its job.
REMEMEBER: the thermostat only sets the MIMIMUM temp the engine will run at, it has no effect on the maximum.
EDIT correction boiling point of 50/50 is 223 not 226. Hum, found both numbers listed on the .net so don't know which is correct.