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2003 Deville
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Discussion Starter #1
The problem with my 2003 DeVille, other than the fact that it downshifts to 2nd gear too readily and shoots forward with the surprising agility of a charging rhinoceros, is that the temperature gauge never moves. Oh, I know it works because I see the motor warm up, but after it reaches the set point it does not budge even on hot days in traffic with the AC on. Darn.

Not so on my '94 Corvette. The temperature needle pops off the set mark a bit on hot days even with the AC off, but once I got the AC working again, fuhgeddaboudit! At 92 degree outside you'd think that a steady 65 on the expressway would give it plenty of cooling air but the needle moved halfway from set point to end point. My question is, on any car, would you drive like that? There is a lot of range on the needle between the 185 degree set mark and the cross-hatching at the end, and one might guess all that clear space means "OK, but be careful". Not a Cadillac question but I'd appreciate your thoughts on this in general - use the full range with caution or run back to safety?
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Our Northstar temp gauges are highly damped at the "12 o'clock" mark - 188 to 210 degrees - because if a gauge ever moves the average owner/driver goes freako and heads for the dealership, causing unnecessary warranty comebacks.

With some A/C comprfessor function set the fans run in SLOW at all times so the gauge should remain pretty steady. The 'stat begins at 188 and is fully open at 206. Your cooling system sounds like it's in good condition - keep it that way. Poorly maintained Northstars have several ways - NOT head gasket failures due to pulled bolts - to cause overheats (275 degrees and Camel Mode).

The Northstars use the same temp sender, so the ticks on the large, small, and digital gauges correspond to this Seville gauge.

My '65 Chevelle Malibu SS 327/350 temp gauge used to move all over the place, summer and winter. That damned useless viscous drive fan.

Get a ScanGauge-II. I watch coolant temp, ignition, vacuum, and intake air temp in real time, You can set pages of any other 4 gauges depending on what your car's PCM/data bus supports.


Temp gauge - my numbers.jpg
 

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White Diamond '03 DHS (with DTS floor shift)
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At 92 degree outside you'd think that a steady 65 on the expressway would give it plenty of cooling air but the needle moved halfway from set point to end point.
That is 245°. It is not normal and is above the normal operating temperature. Might want to check the purge line to be sure it is clear and is flowing coolant. Check it when cold for safety reasons.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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The needle on his Corvette temp gauge went there ..........

He said his Deville gauge warms up and sits at 12 o'clock.
 

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2003 Deville
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Discussion Starter #5
Our Northstar temp gauges are highly damped at the "12 o'clock" mark - 188 to 210 degrees - because if a gauge ever moves the average owner/driver goes freako and heads for the dealership, causing unnecessary warranty comebacks.
Makes very good sense.

With some A/C comprfessor function set the fans run in SLOW at all times so the gauge should remain pretty steady. The 'stat begins at 188 and is fully open at 206. Your cooling system sounds like it's in good condition - keep it that way.
...

Get a ScanGauge-II. I watch coolant temp, ignition, vacuum, and intake air temp in real time, You can set pages of any other 4 gauges depending on what your car's PCM/data bus supports.
I like this product for the Deville, but the 'Vette apparently has OBD1 codes on an OBD2 connector ... I guess you meant this recommendation for the Caddy. It does have one coolant issue - check coolant level sensor is apparently fubar. It comes up all the time on the DIC but if I check the next day with the car cold it's generally within an inch of the top of the overflow tank.

I worked part time for UPS once and one day the van they gave me one day only had the most feeble heat. When I mentioned this to their mechanic seems the van had NO thermostat, in the apparent belief this would delay overheating. He put one in for me.

Another car 101 question: when you say "keep it that way" would asking my friendly local oil change convenience place to flush the radiator generally take care of this or is there something else?
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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The GM change from OBD1 to OBD-II came in the beginning of the 1996 model year - about July of 1995.

You can find the coolant level sensor reed switch online for about $10 or so. It pulls straight down out of the surge tank and won't cause a coolant spill. It's a magnetic reed switch in a sealed tube. See the cutaway.

Do a DEX-COOL exchange every 4 years, recommendations notwithstanding. Have them check the purge line for flow and rod out the water crossover hollow bolt/nipple purge line fitting. The purge line is a small constant bleed back to the surge tank that removes air bubbles from the system, thus assuring "solid" coolant to the water pump.

I would stay away from ANY Oil Doodle service and trust the car to a good local Mom&Pop shop. Too many Oil Doodle horror stories out there............

Water crossover assembled.gif
Deville 2000 reservoir tankside.jpg


coolantLEVELsensor600.jpg
 

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For our 1998 - 2005 FWD Northstar cars the cooling fans go to SLOW at 224 degrees, FAST at 236. The engine cools to 213, fans shut off, the cycle repeats - usually in slow or stopped traffic. They don't run at over about 30 mph - not needed.

BUT - if some A/C compressor function, including DEFROST, is set then fans run in SLOW all the time to assure airflow through the condenser in front of the radiator...... so that's when your temp gauge would tend to stay pretty steady.

Turn OFF the HVAC system - OFF, not AUTO - and watch the temp gauge in city driving. Not to worry - the engine doesn't overheat until 270 or so and if the system is operating correctly it will not go over 224.

Fan control circuit-2000+.gif
 

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2003 Deville
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Discussion Starter #8
Thank you for the wealth of insight, Submariner. I do in fact have a good mom and pop shop, though only pop comes to the shop - when he gets back from summer vacation I'll show him your instructions.
 

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2003 Deville
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Discussion Starter #9
I found this:

The MGA With An Attitude

A Corvette is not so miniature as an MG but it does suggest the design trade-off that a sports car may have a radiator which is going to rely on an increased coolant temperature to equilibrate heat in with heat sooner than a larger vehicle. Also that since you have all those needles and such maybe the presumption is you are intelligent enough to use them? I did also find a number of pages that suggested a coolant temperature over 220 F may cause problems ... that's 40 degrees to play with anyway. Assuming the gauge is actually marked with numbers and not just tick marks -- I can't actually picture it at this moment so there is nothing for it but to go out for a drive.
 

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White Diamond '03 DHS (with DTS floor shift)
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The needle on his Corvette temp gauge went there ..........

He said his Deville gauge warms up and sits at 12 o'clock.
I guess I misread it. Sounds normal to me as well. Disregard post #3.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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The MGA with an attitude ................... back in the late 50's my 1953 MG-TD received an Edelbrock-tricked-out 1938 Ford V8-60 and an Austin truck rear end. No lumps, bumps, or bulges. The ultimate Jaguar eater.

A V8-60 was a tiny flathead engine, about 3/5 the size of a Chevy 283 engine.

TEST-DRIVE-1953-MG-TD.jpg


614d79643c9d4031fadb964ce607a129.jpg
 

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2003 Deville
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Discussion Starter #12
Very cool car, Submariner!

Looks like a gas to drive, though blazing sun on top of my hair-thinning head has made me reticent of taking the top off anything. As for running hot being normal, I am not as freaked out (ahem, "concerned") as I was the first time I noticed the gauge going this high, while at the same time looking for anything which is impeding the efficiency of the cooling system is never a bad idea? The temperature gauge multiplied gradations in my mind; there are just three inter-tick segments between set point labeled 185 and the end point labeled 260, so 25 degrees/segment and just over 220 in the middle of the second one, coincidentally.

Normal or not, I'm also wondering about the way the stick and I presume the attached segment of drive train kicks up an inch or so when punched ... but that's another topic.
 
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