Hi
OK...heres the truck:
94 Full-Size Blazer 4x4
5.7L TBI
I've had a new crate engine installed last year along with a new rad, thermostat, & water pump. Recently, i also replaced my muffler with a Flowmaster model.
The problem I am having is that as I drive my truck and the engine warms up, the temperature gauge never reads beyond 50-60 degrees celcius. At the same time, after a short while of driving, especially at a constant high speed (110km/hr), the 'SERVICE ENGINE' light comes on. I have yet to notice any abnormal engine behavior, sounds or smells, and it seems after slowing down or stopping for a short time, the light goes off. However, the temperature never increases to the normal operating temp of 90-100 degrees. Coolant levels are fine.
I am curious as to whether or not the thermostat itself is at fault and staying open. If this is so, I must be suffering poorer fuel economy and hope I am not ruining the engine.
I have purchased a new TEMPERATURE SENDER (sensor?) but would like the expertise of those of you on here before I go and replace a $35 part for no reason.
Any help or suggestions would be greatly appreciated.
Cheers