Temperature gauge indication - running too cool?

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smtguy
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Temperature gauge indication - running too cool?

Post by smtguy »

My '83 633:
In normal driving the needle on the temperature gauge is typically just to the right of the blue with outside temperature between 70-85F. If the car sits in traffic on a hotter day (95-100 degrees F) it indicates about 50-60% way up the gauge. Is this normal? Or is the engine never really getting up to proper operating temperature when running in the cooler ambient temperatures? I realize that in Southern California, the outside temperature swings are mild and are not nearly what they are in most of the rest of the world, but it just seems that the engine should typically run a little warmer to achieve operating efficiency. If I were in a cold weather state during colder months, I doubt that the needle would make it out of the blue.

I have not measured the temperature yet, but also don't know what it should run at. What thermostat is recommended? Any insight is much appreciated.
1983 Bronzit 633CSi 5 speed
2004 Audi TT Quattro 6 speed

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clipper47
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Re: Temperature gauge indication - running too cool?

Post by clipper47 »

Think this might provide some guidance...
viewtopic.php?t=27431

Yes the gauge is definitely reading low or the gauge is accurate and the engine is running too cool. I live in a climate where I drive my 635CSi in below freezing temperatures and with a 195F thermostat the gauge reads slightly below the middle of the gauge when moving and at about 12 o'clock while stationary idling .
Dave
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smtguy
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Re: Temperature gauge indication - running too cool?

Post by smtguy »

Thank you Dave. Since thermostats are cheap, I think I will replace mine and see if there is a difference.
1983 Bronzit 633CSi 5 speed
2004 Audi TT Quattro 6 speed

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plip1953
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Re: Temperature gauge indication - running too cool?

Post by plip1953 »

I was thinking thermostat, rad cap, faulty sender or gauge, or even a seized viscous fan?
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tschultz
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Re: Temperature gauge indication - running too cool?

Post by tschultz »

Generally it should sit at about 11:30 on the gauge and shouldn't go much past 12 unless it is 100F and you are having to sit in some traffic...

Check your fan clutch and thermostat first.
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Drew
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Re: Temperature gauge indication - running too cool?

Post by Drew »

An IR thermometer might be useful here. With an engine at running temp the stat housing should be 85-90 C I would think.

Anyone else checked coolant system running temps?
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Re: Temperature gauge indication - running too cool?

Post by GRNSHRK »

I snagged this pic a while back, from an E28, but should be the same for series II 6ers :-k

Agreed on using an IR thermometer, got one recently to measure oil temp for deep frying turkeys, very handy tool =D>

Cheap at Harbor Freight #-o
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Brucey
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Re: Temperature gauge indication - running too cool?

Post by Brucey »

150 F = 65 C
180 F = 82 C
195 F = 90 C
210 F = 99 C

The gauge works as indicated provided the sender is good and the gauge is good. Both can (and do) go wrong.

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smtguy
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Re: Temperature gauge indication - running too cool?

Post by smtguy »

Thank you for the suggestions gentlemen - I will work through the list and see what I can figure out.
1983 Bronzit 633CSi 5 speed
2004 Audi TT Quattro 6 speed

Scott
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