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1997 Professional Chassis Raised Roof Presidential Limousine
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Discussion Starter #1
I just bought this car at an auction. The low coolant message light was on so I added about 3 quarts of water to the overflow tank. Let it idle a few minutes and saw no leaks so I decided to drive it 15 miles home. Had the coolant temperature in the display just to monitor things. Air temp was about 93F and on the highway it showed a steady 196F coolant temp. Once I got into stop and go traffic, it went up to 208F, then 213F, and finally 223F when I got home. Also, as I stopped at lights, the oil lamp would flicker on and off unless I put it in neutral. Once the STOP ENGINE message came on for low oil pressure. How much of this is normal in this heat? I don't know what weight oil it has now but how high can you go? 20W-50?
 

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White Diamond '03 DHS (with DTS floor shift)
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Use 10W30 and replace the oil pressure switch. Test the coolant for exhaust gases. 223 is not very hot. Just a tad above normal and just to the point where the cooling fans turn on.
 

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1997 Professional Chassis Raised Roof Presidential Limousine
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Discussion Starter #4
This is my first Northstar powered Caddy and I think the first one with a temperature readout so actually seeing the temperature rise to over 220 got me worried, especially since the overflow tank was low. I guess if it just had a light which at this temperature would not have illuminated I wouldn't have been concerned. The engine was a steady 196F for the 10 minutes at highway speed and from what I hear 223F is hot but not overheated especially in 90+ weather, plus I didn't notice any steam from the exhaust or any water in the oil so I'm not ready to call it a HG problem, or any problem for that matter. I'm more worried about the oil light flashing at idle but since I don't hear any engine knocks or other bad noises, I'll check the pressure with mechanical gauge first.
 

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97 Deville
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Yeah i wouldn't call it a head gasket issue i hate the fact that whenever someone has an overheating problem on a Northstar engine people automatically assume that it's a head gasket problem all cars are different and we don't always know if the car was properly maintained. Anyways i have 97 deville and the temp on the highways has been pretty normal at 196F there has been times where it has been as low as 187-192F but with cooler temperatures and i live in Florida so thats not very often. But the hottest temp i have seem my caddy at is 228F while being stuck in 5 o'clock traffic in 90+ degree weather and the A/C on. I would test the coolant like Ranger said he is usually right on point for most problems.

Enjoy your new Caddy
 

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White Diamond '03 DHS (with DTS floor shift)
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FWIW, my '97 ran a consistant 206 in the summer and 213 in the winter. IF, and I emphesize IF, it is a head gasket, you won't see coolant in the oil, and won't see steam out of the pipes untill it gets pretty bad. How low was the coolant. There is a level sensor in the surge tank that should alert you when it gets low. Something is wrong if you got a "STOP ENGINE" message at 223 degrees. You should not see that till about 260.
 

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01 Eldo ETC, 02 Deville SOLD!
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Range, could the OP have gotten the message due to a (perceived) low oil pressure condition? If the pressure switch is bad, and/or he was a bit low, the computer might get cold feet, so to speak, and ask for a cessation of the internal combustion, if you get my drift... :) That's what the original post seems to infer.

In any case, a good cylinder pressure test will remove (most) doubt about a HG, and then I'd just recommend cautious maintenance for the first month or so - checking the levels, looking for spots underneath, etc etc.

My 99 DV hovered at 196 on the road, and would waver between 205 and 220 whilst paused at a light, in hot weather, with the AC on. I don't think that's any big deal.

The Eldo pretty much does the same thing.
 

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White Diamond '03 DHS (with DTS floor shift)
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Never thought of that Jim, but you are probably correct. The stop engine message was most likely triggered by the oil pressure switch. Shame on me for not thinking of that. Good catch.
 
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See if by chance anybody threw in some vasoline with the purchase. Check the trunk, etc. Chances are you will soon learn what it feels like to be a woman. There is a reason it was traded in; head gaskets!.
 

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The coolant temps you are seeing appear to be normal, I wouldn't be too worried about that. The engine will continue to rise in temp at idle or stop and go traffic to some degree. If you're cruising and the temps stay at 196, I'll bet your good to go regarding HG. Just make sure your ratio of water/antifreeze is correct.

The oil pressure issue is what I would be concerned with. Did you check your oil level?

I'd either replace the sensor and see what happpens or take it to a shop where the pressure can be checked. Good luck!
 

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94 ETC,97 STS
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Ranger's first response was exactly what I would have said.

If you get overheating get the coolant tested for exhaust gases at a radiator shop before you start doing a lot.
 

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1997 Professional Chassis Raised Roof Presidential Limousine
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Discussion Starter #12
I bought the car while visiting my mother in Florida so I don't have any tools to work on it there. Since it ran fine on the highway I think I'll try my luck and pick it up in a few months when it's cooler and drive it 1000 miles home. Oil level looks like it's overfilled so I would change it anyway. Put the car in storage so there is nothing I can do now to it until then.
 
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