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Discussion Starter #1
I replaced my radiator about 6,000 km ago, and all was fine. Just recently, I've noticed that my temperature gauge is reading higher than normal (210°F according to my Ultragauge): the engine gets to temperature (210°F) and stabilizes, and isn't affected by speed or outside temperature - i.e. it's the same at highway speeds and at idle, and at 0°C and -20°C. The only time I've noticed it drop back down to "normal" is when I accelerate hard; after doing so, it slowly creeps back up to ~ 210°F.

I checked my coolant level and quality, and all seems good; I ensured that fluid came out of my bleed screw, so it should have plenty of fluid (and besides, it was running at normal temp when the weather was warmer, 6,000 km ago!).

Could this be thermostat? Water pump going? belt slipping on thermostat (although there hasn't been any voltage changes from the alternator)? I also noticed that my electric fan is not coming on when I'm idling at temperature, which surprised me.

Thanks for any help!
 

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well it could be your thermostat sticking partially open causing it to run hot

your mention the electric fan does not seem to be coming on when it is supposed to

Not sure if you have dual electric fans or not but if so pull the connector off the front of the water pump, both fans should come on shortly (with engine running)

If one does not check the relay in under hood panel PS fender. Pull the relay and look for signs of heat, melting of the part it plugs into and the prongs of the relay

GM issues a TSB way back when for this and the fix was moving the relay out of the box. Gary at innovativewiring.com makes a nice kit for this and GM also sells a part for it but IMHO Gary's stuff is better

tired or burned out fan motor and radiator getting clogged are other possibilities but I would look into the other notes I mentioned frst
 

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Discussion Starter #3
Thanks. I bought (and verified) a new thermostat to install sometime soon. Can I just use (fluoro)silicone to re-seal the housing to the block, or do I need a special gasket (or can I re-use the old one)?

I have the mechanical/electrical setup; even in the summer, I only hear the electric come on in very extreme conditions, but the temperature is always reading lower than what it is now (always well below the little thermometer on the gauge, whereas, at 210°F, the needle is over top of the bulb of the little thermometer). The mechanical fan is working, and its clutch feels about right.

With a new rad, and nice, clean fluid drained from the old one, I'm not too concerned it could be a clog.

I felt the radiator today after letting it idle and getting right up to temperature, and it wasn't very warm (it was a bit, but not much). Not sure if that's normal, but I expected hotter.
 

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You could have a faulty sending unit for the gauge. It is not the same one as the one for the computer. I guess you will find out when you install the thermostat. You can use any gasket that works.
 

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I have the mechanical/electrical setup; QUOTE]

,,ah didn't see Caprice in sig. the EL fan is secondary so if mechanical is working and you feel the clutch fan is good that part should be fine

thermostat is suspect so change.

also a Fred notes...your gauge could be not reading correctly

Do you have any signs of overheating beyond gauge readings..lke steam or leaks?
 

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Discussion Starter #6
No steam or leaks, thankfully.

I didn't know that there were different temperature readings for the gauge and the computer, that's interesting! Is the reading from the OBD port the gauge value or the ECM value? That is where I read the 210°F value. The fact that the gauge will fluctate under hard acceleration, and is always coming up to the same temp, suggests to me that it's probably okay, but then again, electronics can fail in weird ways. I'll hope the the new thermostat does the trick, I guess!
 

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With the engine at operating temperature, feel radiator across the bottom an top and from side to side. there should be no noticeable temperature difference.
It is possible that the radiator could have some blockage. I would think it would be near the bottom.
 
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