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1997 Cadillac Seville STS
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14 Posts
Discussion Starter #1
So on cold starts the car struggles to start but its only intermittently. The car idles good when it does start until it reaches operating temps then it idles very rough. After about 10 mins of being at normal temperature it instantly over the course of 1 minute reaches almost red on the temperature gauge. I figured the head gasket is probably screwed so I know that is an issue but I find it weird that it instantly heats up like that. along with the overheating the coolant all spills out of the overflow and I have to put more in. Just to make it known I am not using normal coolant but just fresh water because it would be expensive to keep filling up to coolant and just to have it boil out.

Now a couple times after being hot it drops instantly back down to normal temperature. I think it may be a bad thermostat mixed with head gasket issue but I am not sure. Also this code shows up when it does get hot

http://www.obd-codes.com/p0155

P0155 - 02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)

Read more at: http://www.obd-codes.com/p0155

Thanks guys and I really hope to find a solution as this car is my life.
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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68,504 Posts
Are the cooling fans running ? And at what temperatures under what conditions ?? A/C on or off ? The thermostats on these engines are extremely reliable, and are set to begin opening at 188 and fully open at 206. Normal, and a foolish change to a "low temp" thermostat will create more problems than you want.

If your ECT and/or fan system is dysfunctional then the engine WILL overheat from just sitting at idle over 10 - 20 minutes.

Water pump drive system in perfect condition ?

Please study the several sticky posts above this one on the main Northstar page - the info on cooling systems, gauges, fans, and other cooling questions.
 

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98 eldo/KD54 w/N37,T96,QA1,D55,DS3,U1Z. U3R next
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2,125 Posts
Replace the 02 sensor. The heater element in the sensor is done.

Check water pump tensioner, and belt. Check water pump tensioner pulley for abnormal sounds or roughness in spinning/operation.

Do you smell coolant when vehicle is shut off or hissing sounds?

Coolant crossover gaskets are made out of garbage.

It's like they should be routine maintenance items. Over a period of time the gaskets construction disintegrates from so many heat cycles. This will become a slow leak point in the coolant system. The gaskets loose their ability to seal perfectly and you develop leaks that go unnoticed until one rears it's ugly head with a leak you can spot.

Check all other hoses and clamps for effective seal.

Check the obvious, the thermostat. Make sure the system is actually full with coolant. This can take a while to get the air out. Air in the system will make the temperature swing wildly.

Water boils at 212. Straight water isn't a great idea but I understand your situation.

Pull the spark plugs and note the cylinder they came from and they color they appear......

Good luck.
 

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1997 Cadillac Seville STS
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14 Posts
Discussion Starter #5
I can hear the cooling fans kick on once it gets hot around 2 oclock on the gauge. Ac off and i replaced the cam pully that drives the water pump because it was torn apart
 

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98 eldo/KD54 w/N37,T96,QA1,D55,DS3,U1Z. U3R next
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2,125 Posts
Cam pulley got destroyed by tensioner......replace the tensioner pulley minimum otherwise the whole assembly.
 

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Registered
1997 Cadillac Seville STS
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14 Posts
Discussion Starter #7
Yeah I believe the tensioner is too tight is that a thing and could I cause my issue?

Also too add on I believe the radiator is now cracked somewhere because coolant is pouring out of what seems to be the radiator unless its the clamp that is loose

WHY IS EVERYTHING BREAKING
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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68,504 Posts
If the water pump drive system is in good order that tensioner arm and pulley will be TIGHT. It should take either a wrench on the arm lug or a 1/4" drive socket handle in the square hole in the arm to lever the tension to even begin to turn the tensioner pulley itself.

ANY weeps or leaks must be repaired before hanging your hat on other possibilities ....................
 

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98 eldo/KD54 w/N37,T96,QA1,D55,DS3,U1Z. U3R next
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2,125 Posts
All, the stuff you're talking about breaking probably have been severely overheated.

Radiator tanks are plastic, under hood operating temperatures combined with an overheating engine spells doom to plastic components. Routine maintenance is a must on a northstar. You can't drive it till the wheels fall off.

Not any car.....
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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68,504 Posts
Routine maintenance is a must on a northstar. You can't drive it till the wheels fall off.
It would appear that, over the years of work in this website, most Cadillac drivers never even open the hood until bells and whistles begin sounding.

"It's a Cadillac - it doesn't need checks and maintenance !"

Duh !!! What's a dipstick for ???
 
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