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1997 cadillac seville sls
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12 Posts
Discussion Starter · #1 ·
I've had this '97 for a while, and everything was ok at first, then the heatercore busted, replaced that, thermostat is new, no lines are clogged, sealent pellets we're added on refill, car has no missfires at all, im looking for a answer other then headgaskets, car runs perfect, fans dont kick on at 12 o'clock like some people suggest they are supposed to. could that be the problem? and the only code the car gives me is knock sensor, but the car runs perfect regardless. thanks for any help.
 

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1997 cadillac seville sls
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12 Posts
Discussion Starter · #3 ·
well atleast now i know its not my fans, thx for the info. also, the car rarely steams.
 

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1997 cadillac seville sls
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12 Posts
Discussion Starter · #5 ·
its just really random, sometimes 230, sometimes till the red mark and the car shuts down, it randomly fluctuates, coolant loss is also at random times, and the car has no smoke/steam when over heated. and the cap does sometimes build up pressure. also before i forget again, today, after leaving a gm garage, the car overheated well past 250, pulled off and about 30-45 seconds later, it just cooled right off.
 

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Super Moderator
2010 DTS
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88,145 Posts
No engine will cool down from 250 in 30 - 45 seconds. I wonder if this might not be an indication problem.
 

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1997 cadillac seville sls
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12 Posts
Discussion Starter · #7 · (Edited)
could it be the coolant temperature sensor?

-update
CTS isn't giving a code, only knock sensor again, also, purge line is just releasing steam, no fluids, ill check for a clog later, its pooring the rain here and its giving me alot of trouble to get off.
 

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Super Moderator
2010 DTS
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88,145 Posts
CTS? Are we talking about two different cars?

Steam from the purge line indicates that it is clear. It also indicates that there is air (or exhaust gases) in the system. Upon further thought, maybe that 30 - 45 second cool down IS possible. The scenario I'm envisioning is this. The HG is leaking and putting hot exhaust gases into the cooling system (thus creating steam). The air pocket moves to the ECT (Engine Coolant Temperature) sensor and the gauge goes up. You start driving, the RPM's go up and so does the water pump RPM, thus moving coolant, which sloshes past the ECT sensor and rapidly brings the indicated temperature down. Add to that your random coolant usage. I'd get a block test kit and test the air in the surge tank for the presence of exhaust gases after the next overheat episode, but do not top off the coolant before doing so. That will condemn or clear the HG's and we can go from there.
 

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1997 cadillac seville sls
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12 Posts
Discussion Starter · #9 ·
cts (coolant temperature sensor) was what my local autoparts store called it, and im guess im just gonna break down and change all the gaskets, already got the kit a fhew weeks ago, thanks for all the information. ill update once there changed
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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73,440 Posts
ECT sensor - #3 in the GM diagram. (From a 2002 Northstar, NOT a 1997, so the IAC/ISC is different on yours........)(
 

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1997 cadillac seville sls
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12 Posts
Discussion Starter · #12 ·
lol its cool, father has been a mechanic for over 30 years, he had be buy the kit right off the bat, ive just been trying to find a way around it :p
anyone know if this job will require special tools?
 

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03 STS
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2,527 Posts
by kit do you mean headbolts? you need a timesert kit if your going that route. buy it, and than sell it when done. internet is great for selling tools. need a puller for cam w/p pulley. balancer puller too to get front cover off. engine hoist to pull motor or lift car. don't kill yourself and pull heads in car. you can use studs but that might conflict with your kit you got. should change most gaskets, front cover, valve covers and so on. silicone gaskets get flat after 14yrs. intake gaskets also.
 

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1997 cadillac seville sls
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12 Posts
Discussion Starter · #14 ·
the kit i have came with gaskets from the heads and up, i got the w/p and balancer pullers, i got a engine puller also, but do i have to actually pull the motor to change them?
or would it be easier to drop the subframe? and do i have to have a timesert kit?
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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73,440 Posts
Look down in Discussions: Northstar Performance and in Cadillac Technical Tips. Many threads on engine (subframe) removal. Your life and the quality of work will be MUCH easier if you lift the car off the drivetrain.

You will absolutely need to use the Norm's Inserts (www.huhnsolutions.com) or Jake's studs for this job.(www.northstarperformance.com) DO NOT attempt to simply replace the head bolts.

You have a lot of precision machine work ahead of you. Go carefully. Go clean.

Please
subscribe your car to www.alldatadiy.com. Trust me, you will need the information. This is NOT, by any means, a Briggs and Stratton.
 

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1997 cadillac seville sls
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12 Posts
Discussion Starter · #18 ·
i really think i might try one last thing, blue devil head gasket repair, i know most people hate these gasket repairs in a bottle. so do i, but this stuff has good reviews and one of my friends used it, but is it safe to attempt in a N*?
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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DON'T DO IT !!!!!

The problem with gasket repairs in a bottle is that you're chasing a moving target: Northstar head gasket failures are not due to the gasket itself; rather, the head bolt hole threads in the cylinder block have failed, allowing the bolts to pull loose, allowing the gasket to blow. The bolts will continue to loosen, regardless of WHAT you try to stick it all back together with. You have to fix the cause, not the symptom.
 

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DON'T DO IT !!!!!

The problem with gasket repairs in a bottle is that you're chasing a moving target: Northstar head gasket failures are not due to the gasket itself; rather, the head bolt hole threads in the cylinder block have failed, allowing the bolts to pull loose, allowing the gasket to blow. The bolts will continue to loosen, regardless of WHAT you try to stick it all back together with. You have to fix the cause, not the symptom.
:yeah:
 
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