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2006 Cadillac DTS
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Discussion Starter #1
I am a new 2006 Cadillac DTS owner. I am almost positive that air has gotten into the system one way or another. Since there is not a radiator cap (just a reservoir cap), I am not entirely sure on the process supposed to be used. I have had mixed answers from several people and wanted to get some answers from some people that have actually owned one and most likely went through this already. Any help is greatly appreciated
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Welcome Aboard !!!

Your Northstar, like many "modern" engines, is fitted with a pressurized surge tank instead of a coolant recovery reservoir. A hollow bolt/nipple at the high point of the water crossover connects the purge line to that surge tank. The purge line should flow a constant small stream into the surge tank whenever the engine is running. The surge tank sits on a T in the heater/block circuit - the purge line removes air and gases from the coolant by allowing them to collect in the surge tank airspace - that tank should be 1/2 - 3/5 full at ambient cold temps.

If your surge tank is overfilled at ambient cold any excess coolant - which expands rapidly during warmup, creating system pressure - will blow out the surge tank pressure cap and drain to ground.

Here's the water crossover - follow the purge line from the connector nipple/hollow bolt. (If cooling system sealants or magic potions are used the purge line may clog, thus causing overheating.)

Water crossover assembled.gif
 

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2006 Cadillac DTS
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Discussion Starter #3
Thank you

I have already checked the see if the hollow bolt is clogged and it's clean as a whistle. I also replaced the thermostat while I was at it. I have heard from people that these need to be backfilled and I have also heard that they need to be idled with the reservoir cap off until the coolant has cycled through the system. Any thoughts?
 

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2010 DTS
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87,744 Posts
If you have opened the system, it is likely that you have air in it.

I have also heard that they need to be idled with the reservoir cap off until the coolant has cycled through the system.
Idling usually won't do it. Run the RPM up to about 2000 or so, or take it for a ride. When it cools down, check it and top off as needed. You may have to do this more than once until the coolant level stabilizes.
 

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Alexandra - 96 SDV Clyde - 15 Silvy
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6,447 Posts
I love the shop manual technique...much like Ranger described, gradually ramp it up to 2500-3000 RPM and back down 4 or 5 times. Do this when the engine is at temperature so that your thermostat is open. Did that the other day on my Silverado and no problem!
 
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