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1999 DeVille
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33 Posts
Discussion Starter #1
Got into my 1997 Deville today and the temp kept rising to 230 which is not normal 196 is what im used to at cruising speeds. Pulled over to check coolant and it was full but coolant wasn't 230 hot but did exit out of the overflow tube a little. Ive had a blown head gasket on a previous deville and wasn't the same situation. so I drove and pulled over when the temp got into the 240s and one thing I did notice was when I stopped the temp would drop 20 Degrees in 5 minutes but would raise rather quickly also. Im going to check the thermostat in the morning any other suggestions would really help me out. Thanks Also no leaks I been paying attention ever since me previous head gasket failure
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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26,323 Posts
Check the water pump drive system and check for a clogged purge line (do a search, discussed endlessly).

If both check out time for a block test.
 

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1999 DeVille
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33 Posts
Discussion Starter #3
Re: overheating problem

Are the 97 and 99 water pump location and removal the same? I have done a water pump on a 99

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Also would the purge line clog all of the sudden with no work being done to the car?
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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26,323 Posts
'97 and '99 WP setups are identical.

Purge line symptoms can pop up pretty quickly.
 

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1999 DeVille
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33 Posts
Discussion Starter #5
Re: overheating problem

ok thank you. no chance it can be the thermostat? I will replace either way
 

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97 DeVille
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172 Posts
Re: overheating problem

Could it be the electric fan on the radiator? Depending on how fast you are going, if it doesn't work, temp goes up as well.
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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26,323 Posts
His first post makes it sound like its overheating at cruising speeds. The fans aren't doing anything for cooling at much over 25/30 MPH.
 

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1999 DeVille
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33 Posts
Discussion Starter #9
Re: overheating problem

overheating at cruising speeds and idle. just skyrocketing

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just went out to check it out and noticed the defrost is not blowing hot
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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70,394 Posts
Re: overheating problem

Purge line - and/or the hollow bolt/nipple at the water crossover end of the purge line - near the water pump cover.

At idle that line should flow a steady stream of coolant into the surge tank - it's a system high point constant bleed that assures "solid" coolant to the water pump - any air or gas bubbles and the pump cavitates - pumps little or no coolant - and the engine overheats.

Proper coolant level is half full, cold. Your thermostat is set to begin at 188 and fully open at 206.

IF the purge line itself is clogged - it - and its rubber connectors can be replaced with a single length of proper sized reinforced rubber fuel hose from any large parts store or NAPA. Use new s/s band clamps.

Defrost ???? Did you check with the controls set to manual (not AUTO) and the temperature dialed to 90 ?
 

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1999 DeVille
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33 Posts
Discussion Starter #11
Re: overheating problem

Yeah the temps for the defrost was set correct but im getting no coolant outta the purge line. put a wire hanger about 2.5 inches in. If I don't get ano coolant outta the hollow bolt its the water pump correct?
 

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2010 DTS
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87,309 Posts
Re: overheating problem

No, if the WP is spinning, it's doing it's job, but it can't pump air.

Overheating motor and no heat from the heater core point to air in the cooling system. Add to that, the fact that you have a '99, it's time for the block test.
 

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1999 DeVille
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33 Posts
Discussion Starter #13
Re: overheating problem

How do you know if the water pump is spinning?
Also its a 1997

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Don't wanna do the block test lol I don't hate much but I hate that test

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The funny thing is I was wrecked into last week and im supposed to take it on Wednesday for the estimate to fix lol I wonder how this will play out
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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70,394 Posts
Re: overheating problem

Let's move this Northstar systems thread to - Engines, Northstar. Lots more visibility there.
 

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1999 DeVille
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33 Posts
Discussion Starter #15
Re: overheating problem

Thank you for all the info. So I started looking around somemore and found that the water pump belt was chewed up and off and that was the culprit to my over heating problem. Now I have one more question how do I remove the pully coming out of the valve cover since I noticed it was worn down a bit?
 

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98 eldo/KD54 w/N37,T96,QA1,D55,DS3,U1Z. U3R next
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2,125 Posts
Unless you have a decent size leak, ex. water pump, coolant connector at crossover, overflow tank, or even leaking coolant cross over gaskets, eventually left unchecked you are going to create hot spots in the motor. This is going to speed up the process of the head gasket failure. The system definitely can't pump air, therefore the system needs to stay filled with coolant, to ensure the motor stays cool and the heater and defroster operates correctly. Any leaks will eventually add air to the system compounding a problem.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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70,394 Posts
The water pump drive pulley - TIGHTLY pressed onto the left (front) bank intake cam extension. Parts in RockAuto - your year, model, engine, belt drive and cooling. Water pump drive pulley, water pump belt tensioner pulley, belt.

Special tools to remove and press on the new pulley. DO NOT pull, bend, hammer on that drive pulley - do it right or it's a guarantee that you'll be in the cam and oil seal replacement business. Check large parts stores for the proper pulley puller/install kit. You pull/push on the groove in the pulley's metal hub - nowhere else. The cam end may still have a black plastic thread protector cap installed. It comes off with a Torx bit.

Tech Tips. This forum. Google "cadillac forums northstar water pump drive pulley replacement".

Pictures and diagrams in my albums - click my username, open the profile. Left column, 2 albums 6 pages of Northstar stuff. Water pump stuff scattered throughout.
 

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Super Moderator
2010 DTS
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87,309 Posts
Use a P/S pump pulley puller/installer to remove the drive pulley.

Be sure to replace the tensioner pulley. It is what seized and cause the belt to slip, burning up your drive pulley.
 
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