i am trying to understand if the temperature gauge is at all accurate in its behaviour. THis is on an 89 TPI 350. It was a V6-V8 swap and i still have the V6 gauges in (minus tach) and i have learned that the number scale is different, so that will account for a small bit of temp difference, but it always runs very hot.

The number on the scale directly down (or halfway) is 105*C (221*F) on the V6 gauge. THe V8 has 100C (212F). As it warms up it goes past that mark way up to roughly the 3/4 mark and then you can watch it drop down close to the 1/2 mark fairly quick, after that always stays above 1/2. After a lot of driving it sometimes comes down to 1/2 or a sliver below but almost always above.

Hooking a laptop up shows the coolant temp come up to 197-200F and just stabilize. The fan comes on at 205 as programmed too. My concern is that would the temp gauge be at all accurate in indicating that the cylinder head temp is actually that high? I put a heat shield around the sender and no difference. It almost behaves like there is an air pocket but i can't see that as possible after all this time. I also find it hard to believe the temp there would be so much hotter than at the CTS and so quickly.

I can't see putting the V8 gauge in changing it's behaviour, only where the numbers on the scale are.

Any thoughts? Is this normal?

 

Sounds fairly normal to me.

The head casting is the hottest part of the motor; the gauge sending unit is in that part. The ECM sees the temp of the water at the water outlet, but only after the thermostat has opened. 2 very different things.

As long as it does the same thing every time, and stays below 235°F or thereabouts under all running conditions, it's fine.