What is a normal operating temp?

redpwny · Mar 12, 2012

Besides the gauge being in "normal" range, It seems a bit high. I finished my tune up yesterday, with all new oil, filter, air filter, sparkplugs, wires, cap and rotor. It never ran warm before the tune up. Now it likes to sit a little above half way. It does not climb higher than that, though... it's about where the hour hand on clock would sit if it were about 930 to 10. Coolant is topped up, the water pump looks new, and fan clutch is good. Does not overheat, just sits high. Thermostat, correct? Do they make thermostats that keep it running a little over the middle of the gauge? Seems odd, is all. I bought a 180deg thermostat I will be installing for peace of mind, but I hope to gain a little insight as to why the car would do this all of a sudden after a tune up.

Thank you!

wythors · Mar 12, 2012

There's no logical reason why doing a tune-up would make a car run noticeably hotter. That said, a 180* t-stat will certainly lower the operating temperature of the engine. What is the condition of the rest of the cooling system? Radiator? Coolant? Waterpump? Fan clutch?

BlownFiveLiter · Mar 12, 2012

As part of your tune-up, did you advance your timing at all?

redpwny · Mar 13, 2012

Yeah I know, I've been working on cars enough to know that as well, there's no reason for it to run warmer. I did not touch the timing, but you never know, maybe I advanced it by accident when dealing with the cap and rotor? I doubt it, though.

The rest of the cooling system is fine- it's a low mileage car, about 120k miles, new water pump, coolant is nice and clean, rad, not sure. Cap is fine. Fan clutch, seems good... so yeah, I'm thinking thermostat. I'll do the 180deg and see what's what.

Gearbanger 101 · Mar 13, 2012

Don't be too concerned with the gauge. The stock temp gauge is little more than a glorified dummy light. Personally, I'd leave the stock T-stat right where it is unless you run into any legitimate cooling problems. Stock coolant temps generally run anywhere from 190F-210F in normal operating range. Lowering the operating temperature will affect your fuel economy, contribute to engine wear, increase emissions output, shorten your oil change duration and have a negative impact on your ECU function. You might get away with a 180F T-stat, but like the old saying goes....if it ain’t broke, don't fix it.

larrym1961 · Mar 13, 2012

I believe I read in a 5.0 Mustang Performance Handbook somewhere that about 200 degrees was an optimum operating temp for the fuel injected 5.0.

redpwny · Mar 13, 2012

Alright, thank you both for the answers. You are right about the adverse effects of going with a lower temperature thermostat- and the car does not ever overheat, so... I will just leave it where it is and keep an eye out for any overheating in the future.

RacEoHolic330 · Mar 13, 2012

larrym1961 said:
I believe I read in a 5.0 Mustang Performance Handbook somewhere that about 200 degrees was an optimum operating temp for the fuel injected 5.0.

Hence the stock thermostat being 195 degrees. Wow, those Ford engineers were really onto to something. huh?

Dino Dino Bambino · Mar 13, 2012

larrym1961 said:
I believe I read in a 5.0 Mustang Performance Handbook somewhere that about 200 degrees was an optimum operating temp for the fuel injected 5.0.

Sounds logical. The stock t'stat opening temp. is 192*F and the low speed electric fan on the SN95 5.0 comes on at 208*F, so it seems Ford intended the 5.0 to run in the 192-208*F range.
A 180* t'stat won't cause any problem. I've been running one for more than 4 years.

7991LXnSHO · Mar 13, 2012

"Don't be too concerned with the gauge. The stock temp gauge is little more than a glorified dummy light. Personally, I'd leave the stock T-stat right where it is unless you run into any legitimate cooling problems. Stock coolant temps generally run anywhere from 190F-210F in normal operating range. Lowering the operating temperature will affect your fuel economy, contribute to engine wear, increase emissions output, shorten your oil change duration and have a negative impact on your ECU function. You might get away with a 180F T-stat, but like the old saying goes....if it ain’t broke, don't fix it."

My gauge went up two letters when I went from a 180 to a 195 deg F thermostat, but it no longer smells so rich as to sting your eyes when your park it in the garge or stop at a stop sign. Get a real gauge to test if you are worried.

Blown88GT · Mar 14, 2012

Tstat sets the lower temp limit not the upper temp limit. A 180 means it won't get any colder than 180 once engine reaches operating temp & tstat opens. Radiator, coolant flow & air flow through it set the upper temp limit.

What is a normal operating temp?

redpwny

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