Temperature Gauge Not Working

[ShadowSwept]

Just a question about my old SE. After it blew a head gasket we had the motor swapped. The 'new' motor came out of a Buick Century. Since the install, overdrive and the temp gauge have been completely non-functional. The high-temp light will come on when it begins to overheat, but the needle doesn't budge, even at startup.
So, I'm guessing the mechanic did something wrong or the Century is somehow incompatible. Anyone know a fix?

[Rico]

Did the mechanic move the original temp sensor when he did the swap? Did he put a new thermostat in the 'new' motor?

If the 'new' motor is overheating then you have bigger problems than malfunctioning gauges and no overdrive.

[ShadowSwept]

I'm aware of that, new motor is pretty much blown, hence the new car. However, we may have a chance at repair but I'd like to get these issues fixed as well.

We changed the thermostat ourselves. I don't know about the temp sensor, where is it supposed to be?

[Rico]

3.1L, 3.4L or 3.8L? What year?

[Rico]

Oh I'm sorry. I see it is the 3.1L.

I can't help you with that.

Maybe someone else will chime in here.

[ShadowSwept]

Yep, 03 Grand Prix SE, 3100.
If this car can be fixed it will be given to my mom, her Blazer keeled over in the street not too long ago.