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2006 dts
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Discussion Starter #1
Okay so here's the deal. i have searched this whole site for my problem but can't seem to find anything so I'm asking for help now. My 2006 dts temp gauge was going up past its normal spot when i was idling or at a stop lights as i would pick up speed it would go back to normal temp. So i called my dad (he owns a mechanic shop) and he told me to change the thermostat, so i listened and did but now it overheats even worse! And it wont go back to normal when i start driving, i checked the purge line when i first started the car and coolant was flowing out of it as was some air and after it got to normal temp i checked it again and there was only steam coming out! I'mnot sure if that is normal or not? I also had the surge cap off when i did both of the purge line tests as i was trying to get air out of the system. I should also mention the the heater would blow hot and then all of a sudden stop blowing hot? What does this mean? Im studying to become a mechanic and i haven't taken engine cooling yet so I'm stumped...will take any help before i dump more money into the car.thanks!
 

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2005 CTS/ 2008 DTS/ 2008 STS V8 N*/ 2011 CTS4 ALL W/D Pearl
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688 Posts
The surge tank needs to be no lower than the coolant arrow about an inch and 1/2 below the black meeting the clear hopefully you know that and can find that mark on you're surge tank.

You still have air in the system is why you are getting steam instead of a slow steady coolant flow from the purge line and a dead give away of air in the system is the heat blowing hot and cold you described.

These Northstars are self purging and do take some time to remove the air in the system at times. The 2006-2011 in particular likes the coolant level up never low or it seems to get hot quick.

Run the car with the heater on full and go for a drive watch you're gauge closely if you take that air pocket out it will put the coolant level low and will start to get hot ASAP so take a jug of coolant with you to top up to the hash mark as soon as you pull over. You might have to do this once or twice the best way is to drive it.

Also make sure the water pump is working look at the pulley and belt tensioner and cam pulley listen for noise there.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Please study the several sticky posts in Engines; Northstar concerning cooling systems, gauge operation and fan operation. There may be something there that applies to your situation.

Your thermostat was probably not the problem. As posted, the correct coolant level is just about at the surge tank midseam, cold (ambient temperature "cold'). The purge line should flow a constant, steady stream, and leaving the surge tank pressure cap off in an attempt to bleed air/gas pockets out of the system is futile - the surge tank always has airspace over the coolant - that's the air "spring" against which the expanding and contracting coolant acts in order to maintain system pressure - which raises the boiling point and assures "solid" coolant to the water pump.

The proper thermostat begins opening at 188 and is fully open at 206, so the engine normally runs at 190 - 200 all day long, regardless of speed/traffic.

Running the heater on "full" really makes no difference - the heater core is full flow at all times - no restrictor valves - temperature is controlled by air blend doors.

What is the condition of the water pump drive system ? Under the metal shroud - three 10mm fasteners for the shroud.

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2006 dts
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Discussion Starter #4
Thanks for the responses i guess it was low on coolant i put 1 gal in it after i had changed the thermostat and then then next morning went and bought another gallon and put it in also now it doesnt overheat thanks for the responses!
 
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