Ok, I came back from a long drive. With the Ex.
I don't usually use the A/C but I put it on. I have the fancy EATC.
Anyway, the temperature is a rock solid 194 when it was on(scan tool temp). On the gauge it is about 47% (not perfectly centered). 198 is dead center.
When the A/C is on, a vacuum valve blocks the core. Makes sense A/C would bring up temperature.
Once the A/C is off, the needle started to move again.
So, I guess the heater core is doing something. Then I found some weird TSB for this engine (4.0 OHV) about a bypass hose from the thermostat area to the lower rad hose. Long out of production. It is supposed to stop noise in the heater core or temp variations. They mentioned steam formation in the TSB. This engine does not have an external bypass, it is a narrow channel in the manifold I believe.
I still am probably going to install the other super-stat to see how it reacts. It is also a 5 deg higher stat so that should help even if it cycles. Looks like a very heavy duty unit. It was like $4 after discount. Gives me a reason to play with the truck too.
I don't usually use the A/C but I put it on. I have the fancy EATC.
Anyway, the temperature is a rock solid 194 when it was on(scan tool temp). On the gauge it is about 47% (not perfectly centered). 198 is dead center.
When the A/C is on, a vacuum valve blocks the core. Makes sense A/C would bring up temperature.
Once the A/C is off, the needle started to move again.
So, I guess the heater core is doing something. Then I found some weird TSB for this engine (4.0 OHV) about a bypass hose from the thermostat area to the lower rad hose. Long out of production. It is supposed to stop noise in the heater core or temp variations. They mentioned steam formation in the TSB. This engine does not have an external bypass, it is a narrow channel in the manifold I believe.
I still am probably going to install the other super-stat to see how it reacts. It is also a 5 deg higher stat so that should help even if it cycles. Looks like a very heavy duty unit. It was like $4 after discount. Gives me a reason to play with the truck too.
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