First off, how many miles are on the engine since rebuilt? A rebuilt engine will run hot till it has enough miles on it to smooth out the cylinders, its not surprising a new engine is hot.
Is the coolant boiling out on the ground?
What type of break-in procedure was performed on the engine? Did it get hot?
Where on the engine is the temp sender screwed in to? I have a 250, not sure where on the 235 it goes.
A temp sender screwed into the head between cylinders will read hotter than at the thermostat just because it's so close to the combustion chamber, and it will continue to heat up once the engine is off.
The temps you need to worry about is what is coming out of the thermostat housing, and what is going back into the engine.
You can purchase thermocouples off Amazon for cheap,( Thermocouple Thermometer Digital K Type Thermometer with 4 Thermocouples,
-328~2500℉ Measuring Range HVAC Dual Channels Temperature Meter Gauge with LED Backlight & ADJ Compensation $28 ) and check the temps while driving.
The getting hot after shut down is nothing to worry about, they all do it.
My 250 would heat up over 220 before dropping back down, did it every time I drove the truck. Once up to temp it stayed right at 200 and then would climb when I shut it off. I cured it by moving the temp probe from the head ( between cylinder 1 and 2 ) to the bottom of the thermostat housing. At the thermostat housing it reads the average water temp of the whole engine. It now runs 180 degrees all the time and still climbs once shut down.
Last edited by Joe H; 04/04/2026 1:46 PM.
