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New t-stat, new gauge reading


austinrick

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Since I bought my '93 XLT 3.0L in 1998, with 120,000 miles (now 360,000 miles), I have run 180˚ t-stats (first went in in 1998, the second c.2008). Normal reading on the gauge has always been needle at or just above the small tick mark above C (iow, basically cold).

Today I installed a Motorcraft 197˚ t-stat and the new normal seems to read between 11 and 12 o-clock on the gauge and that's before turning on the a/c. Is this what I should see? I would think when the t-stat opens, coolant will flow, regardless of the opening temp, and gauge should read similar with either t-stat. With that many miles on the engine I'm sensitive to those head gaskets, etc.

How should that gauge read with a 197˚ t-stat installed? -thx
 


pjtoledo

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on my 2.3 Duratec there is a big difference on the gauge between 180 and 197.
a t-stat regulates the coolant temperature, it doesn't just open and let it all flow.
 

RonD

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Letters on gauge don't help since they change yearly
1/4, 1/3, 1/2 ect.........are better for descriptions

Ford Ranger gauge usually has 210degF as 1/2 way

Stock thermostat was 192 or 195degF, thermostats open at +/- 3deg of rating
And are fully open at 10-15degF above rating.

Thermostat controls circulation to radiator, it doesn't control engine coolant circulation, just flow thru the radiator
When EXTRA heat is detected, t-stat starts to open to let coolant flow thru radiator to cool down a bit
Engines operate better when they are warmed up, just physics, so best to keep them warmed up, and that's why thermostats were added

Normal engine operation should see Ford gauge just below 1/2, 190-200degF, so t-stat is not fully open "normally"
But engine is now Hot enough to get clean oil and get best MPG
The 200deg coolant makes for cleaner oil and better MPG, SAE study, which is why car makers started switching to the higher temp thermostats, in the late 1970's, early 80's
180degF t-stat is fine, its you car and your money

When you carry a load or pull a trailer temp gauge should go up, slightly above 1/2, say 220-225degF, not an issue, official start of overheating is above 240deg

If you have a cooling system problem the difference between 180 and 195 t-stat wouldn't matter, t-stat sets minimum temp, "working" t-stat has nothing to do with overheating

2.3l Duratec should use 180deg t-stat since thermostat is on the LOWER rad hose, not the upper rad hose like most Rangers
So when lower hose coolant is at 180deg upper hose/engine coolant is 15-20deg hotter, so 195-200degF

Most radiators provide 15-20deg of cooling

If temp gauge doesn't get above 1/3 then t-stat is stuck open, or a 160deg, lol
If you start a cold engine feel the upper hose, should be cold of course, now wait 3 minutes and feel it again, should still be cold, no circulation thru radiator yet, if upper hose is warming up with the engine then t-stat is stuck open, which is what should happen when it fails, stuck closed would be a bad thing, lol, but it can happen
 
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cbxer55

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I've had a 180 in mine since, like 2002. Mine is a 98 3.0. With the stock stat, it hovered just below the halfway point. With the 180, it's well below halfway, maybe 1/3.

I run 20W-50 oil in mine, and keep it in there til whenever I get around to changing it. It has a bit over 4000 miles on it right now, and on the dipstick, the oil still looks like oil, kind of amber/honey colored, not black in the slightest bit.

My Ford Lightning came stock with a 180. It now has a 170. Needle stays below where it used to. Oil still looks mighty fine.
 

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