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Cadillac Northstar engine Overheats slowly

Rgant_19

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2006 Lucerne CXL
Hello all!
I am new to the forum and would be greatly appreciated if someone could help me... I inherited my pops 2006 Lucerne CXL with over 140k miles. Now, it hasn’t been driven for like 6 months. When I drove it, it was working fine during the end of the winter month of January, 2019 and during the summer of the same year. Until this fall up to now, it overheats slowly upon cold start. It overheats, then the abs traction disables and the engine light comes on P1258.
So I pull over so I won’t overload it and damage it. I let it cool down for about 5 - 10 minutes... Then I drive away, the temp needle bounces back and fourth and the engine light turns off. One minute it overheats, the next it operates just fine. I’ve change the thermostat and water pump but want to change the coolant level sensor but not sure if that would fix the problem. Also, after this coolant problem, just a lot of other items starting failing. Any help would be appreciated!!!
 
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Rgant_19

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2006 Lucerne CXL
You need to rent a IR gun to determine if it really is overheating or a failing sensor.
Thanks for replying!!! I just bought one but i honestly don’t know how to use it 🤷🏽‍♂️🤦🏾‍♂️. What temp am I looking for on the engine? And where do I point it at on the engine for me to get an accurate temp reading?
 

MelsRegal

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Regal GS 2017
Try the upper radiator hose and thermostat housing, should never go beyond 220 to 225 without the engine fans coming on.
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Robert1955

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2016 Regal Turbo
It could also be a thermostat stuck closed, I had a Sable Wagon that had the temp bouncing all over, replaced the thermostat and all was fine. It would be a quick sub $10 fix, if that's all it is. Good Luck
 

Rgant_19

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2006 Lucerne CXL
It could also be a thermostat stuck closed, I had a Sable Wagon that had the temp bouncing all over, replaced the thermostat and all was fine. It would be a quick sub $10 fix, if that's all it is. Good Luck
Well, that was the first thing I repaired. I went through three thermostats just to make sure if that easy fix was the problem and it wasn’t... They were opening and closing on the high tempered like how they should.. So I do not know if someone else has went through this problem with a V8 Northstar Cadillac engine. I am hoping that it is not blown head gasket 🤷🏽‍♂️🤦🏾‍♂️
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Robert1955

Member
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Buick Ownership
2016 Regal Turbo
Well, I had hopes for you it could be a super simple fix. I have no experiance with the Northstar V8 but I am sure someone here will come thru for you.
 

Regal LTD Coupe

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1993 Buick Regal Limited coupe 3800 (1991 Cadillac Fleetwood coupe 4.9 & 1990 Lincoln LSC SE 5.0 HO)
The common issue on the Northstar is not head gasket failure but rather head bolt failure which in turn caused the head gasket to fail. By 2006 it was about taken care of from the factory though. I would probably install a thermostat that opens slightly sooner if overheating is a concern. Run premium fuel and change the coolant every few years and don't forget to have the transmission serviced as well.
 

Rgant_19

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2006 Lucerne CXL
The common issue on the Northstar is not head gasket failure but rather head bolt failure which in turn caused the head gasket to fail. By 2006 it was about taken care of from the factory though. I would probably install a thermostat that opens slightly sooner if overheating is a concern. Run premium fuel and change the coolant every few years and don't forget to have the transmission serviced as well.
Thanks for the reply🙏🏾. I’ve changed the thermostat 3 times with the failsafe and the one with the temp opening quicker. What will upgrading the fuel to premium will do?
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Regal LTD Coupe

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1993 Buick Regal Limited coupe 3800 (1991 Cadillac Fleetwood coupe 4.9 & 1990 Lincoln LSC SE 5.0 HO)
Actually your year may call for regular.. use whatever it calls for.
 

Regal LTD Coupe

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1993 Buick Regal Limited coupe 3800 (1991 Cadillac Fleetwood coupe 4.9 & 1990 Lincoln LSC SE 5.0 HO)
Seems like the 2006 does call for premium but it has a knock sensor so it can run regular. Not likely related to overheating but a car will often run better and more efficient on premium if that's what's recommended. I believe I read the other day that either 2003 or 2005 called for regular, at least in the Cadillacs.
 

Rgant_19

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Buick Ownership
2006 Lucerne CXL
Seems like the 2006 does call for premium but it has a knock sensor so it can run regular. Not likely related to overheating but a car will often run better and more efficient on premium if that's what's recommended. I believe I read the other day that either 2003 or 2005 called for regular, at least in the Cadillacs.
Oh wow! I didn’t know... I will check up on it too see if that’s what required 🤷🏽‍♂️🤔
 
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