Operating temp: Whats the norm?

[Sevillian273]

90 Seville, 4.5.... Im curious what "operating temp" do all you 4.5/4.9 owners run at? My cooling system is very well maintained at 61000mi and I have both an aftermarket 'analog' temp guage and the factory digital guage and my cad runs around 197 all day long. Some guys talk about 220 or 215 temps but that seems a bit high to me... So Im just curious what everyones running at because Im trying to troubleshoot a possible engine 'gremlin'... I hope Im just paranoid but it seems that something just isnt right....

[HUF]

197 - perfect. You are probably using 190 F thermostat which is what you are supposed to do.

[94_SDV]

My 4.9 runs between 140-150 on the highway. From what I've seen, it appears mine runs too low.

[submariner409]

94, If your car runs at 140 +/- on the highway you're losing a fair amount of gas mileage and the coolant and oil is not heating to a high enough temperature to cook off crankcase acids and moisture for burning in the PCV system.

Your engine probably came with a 180 or 190 thermostat which may have been changed or is currently stuck open. How quickly does the car heat to 140 ? If it reaches that temp by a mile or two, then someone has mistakenly changed to a low-temp thermostat. If the fan (?) controls have been changed, that contributes to the problem also

Current thinking which changes a design temperature setting in order to run the engine colder and somehow gain power is fallacy, and in the long term the practice creates lower fuel mileage and accelerates engine wear. Today's (and yours.....) engine management systems are designed to efficiently operate around set conditions: change one of those conditions and overall performance suffers.

[Sevillian273]

When I first got my Seville, it would hit 230 at lights but would drop below 160 at highway speed, I suspected a sticking thermostat so I flushed, filled, and replaced the thermostat and that took care of it.

[94_SDV]

Submariner, It doesn't take long for it to get to 140-150, not sure about the thermostat as I just bought the car. I don't recall ever hearing the fan come on (there is only one fan, not two. It looks like a mini rad has been installed beside the fan. If I understand correctly, the stock engine has two fans). It does heat up quickly when idling at a stop (up to 190 within a few minutes). What do you think I should look for/do? The car gets 21-22 MPG on highway.

[submariner409]

An electric fan-cooled engine will normally run at about the middle, or just a tad higher, in the thermostat operating range (In my Seville, that's 188-206, so the car runs at ~200). When you stop and idle, or maybe lug up a long hill, the temp will climb to the lower (slow) fan setting (again, in my car, 224 degrees), the fan(s) will come on and the temp should drop pretty quickly back to around 200 or so. (Don't forget that most cars are set up to run at least one fan in slow when an A/C mode is used, so the above won't apply: in that case the car will generally stay at around 200 all day.) If something is really wrong fan(s) go to high at about 236.

OK......If you think your car originally had 2 fans, then something has changed. The extra (?) cooler is a mystery.....what I know about various 4.9 installs is pretty slim.........Did the previous owner do any towing, where do the cooler lines go to/from ? Is there a fan switch (aftermarket) somewhere near the driver's side of the dash.

A 4.9 owner and one who is familiar with your car will have to clarify this one...............

[94_SDV]

I'm not sure if it originally had 2 fans, but all the pics of 4.9's I've seen seem to have 2 fans. There is a small utility trailer hitch on the car. There is no fan switch inside the car. I took the car out for a 5 minutes drive an hour ago and the hottest it got was 140, the usual temp being 125 or so. I take it this is not normal. Any idea how I can test the thermostat, and where it is so I can change it? I don't have the service manual for this car yet. Thanks again.

[submariner409]

As I said, another 4.9 owner will have to bird dog this, but I DO know that 125 - 140 is way too cold for a modern automotive gasoline engine.

[94_SDV]

That probably explains why the heat is only warm and not hot. I bought a new thermostat today, it says "195" on it, so that should do the trick. Any other 4.9 owners only have one fan in the engine, and what looks like a mini rad beside it?

[carnut]

The proper thermostat is a 195. car runs between 195 to 220. radiator fans are commanded on at approx 220 if A/C is off to lower the temp to approx 205

[Sevillian273]

I dont know about you guys but when my 4.5 hits 220 and higher, it runs like crap as if im going up a steep hill. Also the exhaust note changes a bit. When it drops back down it runs just fine again.

[79malibuonblocks]

whoes got a coolant temp gauge? I dont have 1!

[NickySantoro]

Originally Posted by 94_SDV

Any other 4.9 owners only have one fan in the engine, and what looks like a mini rad beside it?

Check the lines going to and from it. Because of the obvious previous towing situation, it might well be an auxiliary trans cooler.

[carnut]

79malibuonblocks you have a temp gauge in on-board diagnostics. It reads in C degrees instead of F degrees but you do have one.