this makes no sense to me

rockyracoon · Jul 19, 2010

I have noticed that my car actually runs hotter when im on the highway than when in stop and go driving.

on the hwy the gauge is on the m of normal
when cruising on secondary roads it is basically right in the middle of the gauge.

the only thing I can think of is the fact that the front air dam is missing.

wmburns · Jul 19, 2010

Remember that the fans do not run when the car's speed is 45 MPH or higher. The thought is that at that speed, there is enough air flowing through the radiator anyway. Besides, the fan is wasting gas/power running when not needed.

At highway speeds, the motor's temperature is mainly regulated by the T-stat. Whereas at slower speeds, the motor's temperature is regulated by a combination of the t-stat and the cooling fan's set points. Further, the fan has two speeds depending upon engine temperature (and AC setting).

I see a couple of possibilities. If you are driving around town with the AC on, the fans run on high all of the time. This may result in more cooling air than the motor needs. Thus a slightly lower engine temperature.

On the highway, the fans don't run. The motor heats up until it is in balance with the t-stat opening.

I personally would not trust the dash temperature guage to make such fine determinations. Normally the anti-slosh circuits in the dash keep the temperature guage from changing very much.

So what does your ODB2 scanner tell you? What about the condition of the cooling system? Radiator clean? Anti-freeze/water percentage good? Is the pressure cap holding pressure? Does the de-gas bottle vent any coolant? Does the motor temperature continue to slowly rise on a long trip?

If the entire cooling system is good, then it is possible that a missing air dam is affecting the amount of air being driven through the radiator under speed. However, if the motor doesn't overheat on a long trip, it most likely is OK.

OBTW, are you enjoying your ride?

ChillPhatCat · Jul 19, 2010

rockyracoon said:
the only thing I can think of is the fact that the front air dam is missing.

That's where I would start, it's there for a reason.

On the flip side, I don't think you really have a problem if it's in the middle of the guage. As wmburns said, the factory guage is not accurate, it's just there to tell you when there is a big problem.

rockyracoon · Jul 19, 2010

gentleman,thanks for the replies.

Mr Burns,I never thought to use my scan tool to rule out the gauge not being that accurate.the mixture is close to 50/50% maybe a tad more water.I seem to remember after swapping the old motor out, that I didnt quite have enough antifreeze on hand,and had to use more water than I wanted to.The hydrometer says im good to +5*.

im really loving the car,getting ready to install some 410s,hoping for a significant SOTP difference

wmburns · Jul 23, 2010

Take a look at post #8 in the following thread.

http://www.stangnet.com/mustang-forums/820262-96-gt-pi-swap-overheating.html

Interesting information about a change in radiator design to improve cooling in 96 MY Mustangs. Looks like Ford made the radiator larger and changed the fan as well.

Also makes sense after a PI upgrade this could become an issue. The radiator was marginal before the upgrade. After PI swap, motor is making more power. More heat into the radiator......

OBTW, a 60% water and 40% anti-freeze is OK for Southern climates. In fact, 60/40 will give better cooling. Do not go below 40% anti-freeze. Rust would become an issue.

this makes no sense to me

rockyracoon

wmburns

ChillPhatCat

rockyracoon

wmburns

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