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1993 Seville STS 4.6L Northstar - 190K Miles!
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11 Posts
Discussion Starter #1
Hey everyone, i have a 93 Seville STS Northstar. I am having an overheating problem combined with others. Just wondering if what i am about to explain can be diagnosed by anyone.

Ok, car has like 190K miles, almost all long highway over 100miles per day. The car overheats now, in the warm weather like now it will only take about 10-15 minutes to completely overheat and shut down. It also has a rough idle from the moment i start the car and it doesnt go away. That seemed to happen the same time as the overheating problem. I also get the ABS and Traction lights now. It doesnt seem to be losing coolant, atleast until it overheats it doesnt.

I replaced thermostat already, no change in problem. Fans do seem to be working alright. Does this sound like it is the head gasket, if so i am not bothering to fix that. Does anyone have any expereince with the same problem or know any other areas besides head gasket i can fix/check to fix the problem.

I really do like the car and besides that everything else seems in good shape, new transmission like 30,000 miles ago. Would like to keep it, but not if its the head.

Any other info needed, just let me know and i will answer as soon and best as i can. Thank you.
 

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1992 Town Car Cartier & 2014 Accord LX MTX
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34,087 Posts
Take it to the dealership and have it diagnosed. You pay the diagnostic charge and figure out exactly what the problem is, it's much cheaper in the long run to do it that way....instead of throwing parts at it.

Good luck though, the 93-97 STS is one of my favorite Caddys of all time.
 

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96 SLS
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160 Posts
Did you check the fan belt on the drivers side of the engine. It is the water pump belt. It is hidden under a cover to protect the belt but can be seen if you look close. Belt is toward the front of the car , drivers side on my 96 SLS northstar. When mine broke, I was on interstate at night in FL. Car started to overheat, run on 4 cylinder and then stop. Dash lite up like christmas tree. Hope that all it is. Pretty easy to change. I changed in parking lot at Advance Auto and used their tools.
 

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1993 Seville STS 4.6L Northstar - 190K Miles!
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11 Posts
Discussion Starter #4
Did you check the fan belt on the drivers side of the engine. It is the water pump belt. It is hidden under a cover to protect the belt but can be seen if you look close. Belt is toward the front of the car , drivers side on my 96 SLS northstar. When mine broke, I was on interstate at night in FL. Car started to overheat, run on 4 cylinder and then stop. Dash lite up like christmas tree. Hope that all it is. Pretty easy to change. I changed in parking lot at Advance Auto and used their tools.

Thanks for the idea SLS GOLD, i will take a look at the belt. I doubt it has to do with that just because i dont have any of the sysmptoms you had, other then it overheating, but i will still check it out just in case. The car has a rough idle, but doesnt seem like there is any loss of power as if it was only running on 4 cyclinders, and nothing lites up in my dash that isnt normally on.
 

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White Diamond '03 DHS (with DTS floor shift)
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86,990 Posts
It does sound a lot like head gaskets, especially with the rough idle, but you should be loosing coolant. Don't over look a clogged purge line or a weak surge tank cap.
 

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1993 Seville STS 4.6L Northstar - 190K Miles!
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11 Posts
Discussion Starter #6
Ok, so if it is over heating, has a rough idle all the time, and is loosing fluid, then is it almost definately the head? Any other things i can easily check to tell if it is definately the head.
 

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94 ETC,97 STS
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3,531 Posts
Take it to a radiator shop and have a coolant byptoduct test done (exhaust gas test). They usually do them pretty cheaply...definitely cheaper than a mechanic. If that's negative you may just have some basic problems.

Let us know.
 

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1993 Seville STS 4.6L Northstar - 190K Miles!
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11 Posts
Discussion Starter #10
Thanks for everyone's suggestions. I found a few local auto radiator places and will take the car out to them to have the test done on the fluid. Will write back when i get the results

IF it is the head, anyone is welcome to buy it. :thumbsup:


no dont drive it into a wall
sell it to me!
 

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02 STS
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1,262 Posts
Put a pin hole in the fuel line, just above the exhaust manifold... A total loss fire will have less of an impact (pun intended) on your safe drivers discount :lol:
 

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1993 Eldorado, 4.9L, 200k miles
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273 Posts
To rule-in or rule-out a head gasket, go to AutoZone and obtain a coolant system pressure tester via their loaner program. You'll pay a $75 core, with a full refund upon the tool's safe return.

The pressure tester basically pumps up the coolant system to operating pressure (16psi?), then you grab a brewski and watch the guage for leakage. If the guage stays steady, then your head gasket is likely ok. The test is done w/ engine cool, and be aware that the gasket could open up at operating temperature.

Additionally, keep an eye on the coolant level and ensure that it stays steady over several weeks of usage. At 100 miles per day, a leaky head gasket would show up in a low coolant level in a short period of time.
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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86,990 Posts
The pressure tester basically pumps up the coolant system to operating pressure (16psi?), then you grab a brewski and watch the guage for leakage. If the guage stays steady, then your head gasket is likely ok.
This test is not conclusive. It may or may not work. In the early stages of a head gasket failure the breach is very small and while the high cylinder pressures are enough to cause exhaust gases to leak into the cooling system, the reverse (low pressure from the cooling system) may not cause coolant to leak into the cylinder until the breach becomes worse.
 

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Seville STS
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15 Posts
May be this will help you, it helps me, take you car to a radiator shop and remove the radiator and clean it, maybe a few pipe lines are closed.

One more thing start you car at the morning and remove the radiator cap, if you see bubbles, I think it a gasket, I hope note.
 
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