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Discussion Starter #1
So I have an 01deville and it has almost 100k on it. I bought it 2 months ago used and it started overheating after a week. Had the system purged manually and it worked fine.... for about three weeks. Then overheated again. Looked at coolant, it was about half a gallon low so I added some. Ran fine. Then I replaced the surge tank and it was good. Then today I parked it on a hill for not even 5 min. When I came out the DIC was going crazy. "Engine coolant hot- idle engine" "engine hot - ac off" "change engine oil" (which is weird considering I just changed the oil 3 weeks ago). There was No ac Running and I let the engine idle after backing the car down off the hill. "Engine overheated - stop engine" so I shut it off, let it cool down turned it back on. Drove a mile and a half and it overheated AGAIN. Had it towed home and here I am. Someone, anyone, ideas?
 

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2002 STS, 2005 CTS 3.6
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Re: overheating problem

Was the hollowed bolt at the t-stat housing that feeds the surge line cleaned out when they replaced the surge tank? A new tank won't do any good if that line is still blocked with crud.

Oli life monitor goes to zero when the engine is overheated, it should be changed now.

Check the water pump pulley and belt for proper operation, maybe the rad, pressure cap and t-stat too.

Lots of pieces involved with an engine's cooling system that need to be working properly or chaos ensues.
 

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Discussion Starter #3
The thermostat was not changed but radiator flush and manual purge was performed. I have not checked the water pump yet. I know I have a slight leak coming from one of the Rad valves But I can't tell if it's a bad hose or bad Rad. Idle What is going on with my car but it's really getting to me.
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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68,458 Posts
Re: overheating problem

Please read centaur's post again and perform the recommended maintenance checks.
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
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19,270 Posts
Re: overheating problem

The thermostat was not changed but radiator flush and manual purge was performed. I have not checked the water pump yet. I know I have a slight leak coming from one of the Rad valves But I can't tell if it's a bad hose or bad Rad. Idle What is going on with my car but it's really getting to me.
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radiator flush and manual purge was performed.
don't know what manual purge is -

check the PURGE LINE for a constant gentle flow of coolant
with the engine running -
 

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Discussion Starter #6
"Manual purge" pulled the purge line off checked for a steady stream. My own term. It's a cracked Rad as I can tell right now. Getting that replaced as well as new hoses. Might get a thermostat as well. Really hoping this fixes it otherwise I have to dig deeper And this is going to get very expensive.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Re: overheating problem

The correct thermostat - AC Delco, Gates, Stant, etc., etc. - is set to begin opening at 188 and fully open at 206. Most Northstars run at 190 to 200 or so, so the thermostat is normally only open 10% to 75% even in August hauling down I-95 at 85.

The radiator end tanks - plastic - tend to crack at this time/age. Replace the whole thing if you have tank leaks. There is a 99.9999% chance that your base Deville does not have V03 HD cooling, so you want a radiator without the engine oil cooler in the passenger side end tank. (IF the car was built with the towing package and V03 that would show on the RPO sticker under the spare tire cover.)

Worried about actual coolant temperatures in these models with no real temperature "gauge" and OBD-II ??? Look at a Scangauge-II. www.scangauge.com - Fun tool for maintenance, engine operation and diagnostics.
 
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