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Deville
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Discussion Starter #1
Hello,
I drive a '98 deville, I recently had a pipe completely rust out that apparently was responsible for transporting coolant to the engine, of course GM stopped producing this part so I had to get my mechanic to put in a 'aftermarket' hose in place of it. He used what he refers to as "blue hose". I've been driving the car for two days now and everything seem's fine so far. I have never really watched my coolant temp before, but I have no clue what the operating temperature should be at. It seems to go high in my eyes when I'm idling (almost 230) but when I'm driving it goes down to about 196-205. I live in New York and today it was about 40 out, are these coolant temperature's normal?

As a side note, could my mechanic not have put a 50/50 mixture of antifreeze/water (I think it's water?) in the system?

Any help would be awesome, thanks in advance!
 

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98 DeVille, 97 DeVille d'Elegance
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7,345 Posts
The pipe is still available new for around 60, both are actually available.
Go down to N* engine forums and read up... Without AC on fans dont even come on slow until @224. So temps sound normal to me.
 

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Deville
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Discussion Starter #3
Really? The pipe we needed we tried to get from two local cadillac dealers, both said the part was discontinued..
 

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White Diamond '03 DHS (with DTS floor shift)
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195-205 is normal, but 230 is not.
Have you checked to be sure that the purge line is clear and flowing coolant?

I take it you are talking about the heater pipes that run along the rear head?
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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68,436 Posts
This full-sweep temp gauge may be a bit different from your shorter sweep gauge, but the temperature markings represent the same values. With no function set that calls for the A/C compressor to run, fans go to SLOW at 224 and fast at 236. If you set some function that calls for the compressor to run (DEFROST, for example) then fans run in SLOW all the time and the gauge should sit about mid-point at all times.

The purge line runs from the hollow bolt/nipple (maybe through a throttlebody circuit) over to the top side of the coolant surge tank. If that line/nipple is clogged the system cannot pass air and gas into the airspace over the coolant in the surge tank; the water pump cavitates and loses pumping efficiency, possibly causing a near-overheat condition.

Please study the several sticky threads at the the Engines, Northstar forum - concerning cooling system operation, fan operation and gauge operation.
 

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Deville
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Discussion Starter #6
This morning on my way to work (about 15 miles) the coolant temperature sat at about 197 the whole time (after it was warmed up obviously) I stopped at a stop light for about 20 seconds and the temperature rose to 206. Once I started driving again it went down to 201. Once I got to work I idled in the parking lot for about 30 seconds and it went to 203.
Is it complicated to clear the purge line/check if it's clogged?
Also yes I am talking about that Ranger, thank you both for the replies.
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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26,323 Posts
Those temps are absolutely normal.

Clearing the purge line is easy. It's not the line itself that clogs, it's the hollow bolt/nipple on the engine, and in some cases, the nipple on the surge tank. Disconnecting the hose and "rodding out" the holes with a hanger or long nail is all you have to do.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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With no A/C or DEFROST function set, those temperatures - driving, traffic light, slow drive, park - are normal.

Look at your purge line. Two possibilities for your year - it either runs across the engine from the hollow bolt/nipple at the water pump cover to the surge tank or it runs from the hollow bolt/nipple to/from the throttlebody nipples thence to the surge tank.

If you disconnect the line from the bolt/nipple and surge tank you should be able to blow through it. If not, it's clogged. If the line is clear but does not flow a steady, small stream into the surge tank at idle, then the hollow bolt is clogged. Rod it out with a straightened clothes hanger. If you have a heated throttlebody, that can clog, too. The easiest fix is to bypass it, using a proper sized length of reinforced fuel hose from any parts store. (The reinforced fuel hose easily handles cooling system pressures.)

Google "cadillac forums northstar coolant purge line" and do some homework. (and read those recommended stickys)

heater pipes - Get into the NalleyGMC website - www.nalleygmc.com - or www.gmpartsgiant.com and do some searching.

Oooppppssss !!! MC beat me to it.
 

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Deville
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Discussion Starter #10
Still have not tried anything with the purge line, but I have noted over the past few days that my coolant temp stays a nice 196-205 whenever I'm actually moving. But if I'm idling for a while my coolant temp will slowly rise to about 225. I was wondering if the reason it could go up so high (225) because of the exhaust of a car in front of me raising my temp? I read somewhere that it could, but don't know.
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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The exhaust of the car in front of you does exactly nothing to your coolant temp. Maybe if there's a jet in front of you... :sneaky:

Extended idle/high ambient temps/air conditioning - can all cause the temp to rise enough to trigger the cooling fans, that's what they're there for. The fans don't even go to low speed until 224.
 

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White Diamond '03 DHS (with DTS floor shift)
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Until you confirm coolant flow through the purge line, you're just :banghead:
 
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