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2001 Cadillac Deville/ Northstar engine overheating when A/C is engaged!

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The car overheats when AC is turned on.This indicates there is coolant leak or AC low on refrigerant. Get the AC pressure test done.This will confirm if its low or leak.Also get the coolant temperature sensor checked.The thermostat and the radiator.If the radiator cap is loose or releasing any pressure the car will heat when ac turned on.The radiator cooling fan.Check out if the fan turns on when engine reaches at particular temperature,if not then this fan is faulty.The other thing you should look at is a restriction of air flow through the A/C evaperator and the radiator.If there is debris between the evaperator and the radiator then this can be one reason for car getting overheated.Clean the debris get the ac serviced.

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Posted on Sep 16, 2010


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There are a lot of coolant lines around the Northstar engine, but not one called a "purge line" that I am aware of. The coolant system is designed to be a closed system, and is never purged.

However, there is a rubber drain line on the pressurized overflow tank that will release coolant on excessive pressure sensed by the rad cap on the tank, or if the rad cap is faulty. If the system has a leak anywhere, it will not hold required pressure and that will always cause overheating. If you are losing coolant, that is the first place to look (bad rad cap, or cracked tank or line from the tank to the rad).

Oct 22, 2016 | 2001 Cadillac DeVille

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Have a cadie 01 changed water pump and thurmostat and still over heating and running hot any ideas

Try to flush and fill with new fluid to get the passageways free of sediment.

Or, try to see if the fans are coming on at the right speed at operating temperature. May require new fans/relays/wiring to fix this problem.

I have a 1997 Cadillac Deville that was overheating its Northstar engine and it required service amounting to about $700.00 or so from an auto electric shop, but afterwards it ran cooler.

Good luck on this repair.

Feb 05, 2011 | 2001 Cadillac DeVille

1 Answer

Where is the starter on a 2001 Cadillac deville, with a V8 Northstar engine?

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Nov 09, 2010 | 2001 Cadillac DeVille

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When does the timing belt need to be changed on a 2001 Cadillac Deville with a Northstar engine?

The northstar engine uses chain driven cams that eliminates the need to replace timing belts.
Thank you and enjoy,

Aug 09, 2010 | 2001 Cadillac DeVille

1 Answer

I have a 2001 cadillac deville and the temp gauge creeps past the half way point, mainly when sitting and kicks back down to half way.... is this normal?

this cna be normal. The Northstar engine has design issues that manifest as overheating problems, but mainly under hard accelleration...
What you describe sounds like normal fan cycling...are the fans going on and off?

May 30, 2010 | 2001 Cadillac DeVille

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Sep 30, 2009 | 2001 Cadillac DeVille

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Problem with overheating on 1996 Cadillac Deville with Northstar engine. The information screen read "engine overheating", "idle engine" and "change oil" all within one minute. Are these issues related...

The oil life resets to zero after the engine overheats. Check for external leaks first, make sure the water pump belt is still there and turning. The most likely cause if the car has over 70,000 miles is head gaskets.

May 18, 2009 | 1996 Cadillac DeVille

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Overheating,eveything looks ok.

I have a 97 Cadillac Deville with a northstar engine and have replaced it twice so far, so i answer this by experience...i've noticed to my two prior engines that went bad that the normal temp should NOT EXCEED 228 (normal), the red overheating light will come on at 250 and at 260 it will beep and tell you to stop engine - idle engine and will begin to smoke (overheat).

I hope this helps you and anyone the way if your asking why did i replace my engine twice is simply because my cadillac is super clean inside and out, immaculate condition.

Apr 15, 2009 | 1997 Cadillac DeVille

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Replaced water pump. thermostat. radiator, filled with dex col, still overheating This is a 2001 Cadillac Northstar engine

Try backflushing,if this doesn't solve the problem,..then it could be the distributor,they can make the car run hot if the are going out.

Apr 08, 2009 | 2001 Cadillac DeVille

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