Cadillac STS The newest installation of the performance sedan from Cadillac, having replaced the Seville

Dreaded overheating problem, with a twist.

  #1  
Old 06-09-2010, 09:06 PM
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Default Dreaded overheating problem, with a twist.

I have a 98 STS that is experiencing the overheating problem. I am at wits end. Here are the details.

It had never experienced an overheating problem before I parked it. The car sat for about a year and a half without being run (bad starter). Replaced the starter, Changed spark plugs and all wires. Also changed oil and oil filter at this time. Charged the battery, and it started right up. Had about 1/4 of a tank. Added 3 gallons (premium), plus some STP Octane boost.

Car ran fine for about 10 miles (gauge was straight up and down), then suddenly started to get hot. I'm not sure about the actual temperature, but it was close to (but not in) the red. Stopped and let it cool down.

Here are the things I have done to fix the problem.

1) Replaced thermostat
2) Replaced water pump
3) Replaced water pump belt
4) Replaced water pump tensioner

When filling the radiator, I warmed it to normal, then let it set, then filled the reservoir to the right level. I did this twice. After that, it was full when cold.

Car is throwing the following codes:
AMPU1065, IPM B1343, RSS C1763. As far as I know, these are unrelated.

It is also throwing a P 0300 code, which is misfires. I figure it is due to the bad gas. I will be filling it up tomorrow with some premium (assuming I can get it to the station, which is about 5 miles away).

Car is still overheating, but not in a "normal" way.

There is no oil in the coolant, and no coolant in the oil.

Exhaust smells like unburned gas (thus the 0300, I suppose), but it does not have that "sickly sweet" smell that I had on an older car when the head gasket was blown.

Floor boards are dry.

I do not think the lower radiator hose is collapsing, because it is only about 6 or 8 inches long.

Both upper and lower radiator hoses are hot and stiff when warmed up.

I am not losing any coolant at all, as far as I can tell. After it cools down, the coolant is at the same level as when I started it cold.

When it is not overheating, heater blows out really hot air. When it starts to overheat, heater is blowing out cold air.

Both fans appear to be running when it gets past the straight up and down mark. (Of course, I can only check this when idling)

Car "normally" runs just shy of the straight up and down mark.

After replacing all those items, I drove it for about 5 or 6 miles, and it never moved above the normal spot. Then, all of the sudden, it jumps about 1/4 of the way to the next mark. Stays there for a minute or two, then jumps up to the next mark. Repeat a few times, until it is almost to the red. By that time, I'm back in my drive way. Have repeated this several times.

This was on level, and mostly straight country roads. Speed averaged about 45 or so, but in a few spots, I got it up to 60 to see if it would overheat. Made 4 or 5 stops, with turns.

I can't feel all of the radiator, but the parts that I have felt have all felt hot.

The bleeder line to the top of the reservoir tank is not clogged. When warmed up, it spits out coolant. Not in a steady stream, but in bursts.

I find it very odd that it would run steady without overheating, then suddenly jump up and start overheating. I did not run the car very hard.

Once, when the heat gauge jumped up, I put it in neutral and revved the engine to about 4k rpm, and it started dropping back down.

When cold, the upper radiator hose seems like there isn't any fluid in it. I am not in any way, shape, or form a mechanic, but it acts almost like the radiator is only 1/2 full or something. (May the engineer who put in a radiator without a cap spend all of the afterlife working on this car.)

When the engine is warmed up, and running, there doesn't seem to be any "bubbles" in the overflow tank.

I have not done the CO test on the fluid yet, and I haven't done any compression tests, as I don't have anything to test compression. I have not done a cooling system pressure test, because I do not have the equipment.

Any ideas? I'm out of work right now, and money is tight, so I have to spend the absolute minimum. Believe me, when I was working, I just took it to my mechanic and said "fix it". LOL

It's almost like it is getting an air blockage that can't be cleared in the cooling system. I would have thought that if it was a bad head gasket, I'd have to add coolant to the system. Could I possibly have gotten a bad thermostat? (It can't be backwards, it only fits one way.)

Let me know if this isn't enough detail, or if you have any questions. I'm hoping someone will be able to help me out. I guess I'll go tomorrow and get the CO tester for the coolant. I could be wrong, but I don't get the feeling that it is the head gaskets.
 
  #2  
Old 06-09-2010, 10:56 PM
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Originally Posted by 98STS View Post
I have a 98 STS that is experiencing the overheating problem. I am at wits end. Here are the details.

It had never experienced an overheating problem before I parked it. The car sat for about a year and a half without being run (bad starter). Replaced the starter, Changed spark plugs and all wires. Also changed oil and oil filter at this time. Charged the battery, and it started right up. Had about 1/4 of a tank. Added 3 gallons (premium), plus some STP Octane boost.

Car ran fine for about 10 miles (gauge was straight up and down), then suddenly started to get hot. I'm not sure about the actual temperature, but it was close to (but not in) the red. Stopped and let it cool down.

Here are the things I have done to fix the problem.

1) Replaced thermostat
2) Replaced water pump
3) Replaced water pump belt
4) Replaced water pump tensioner

When filling the radiator, I warmed it to normal, then let it set, then filled the reservoir to the right level. I did this twice. After that, it was full when cold.

Car is throwing the following codes:
AMPU1065, IPM B1343, RSS C1763. As far as I know, these are unrelated.

It is also throwing a P 0300 code, which is misfires. I figure it is due to the bad gas. I will be filling it up tomorrow with some premium (assuming I can get it to the station, which is about 5 miles away).

Car is still overheating, but not in a "normal" way.

There is no oil in the coolant, and no coolant in the oil.

Exhaust smells like unburned gas (thus the 0300, I suppose), but it does not have that "sickly sweet" smell that I had on an older car when the head gasket was blown.

Floor boards are dry.

I do not think the lower radiator hose is collapsing, because it is only about 6 or 8 inches long.

Both upper and lower radiator hoses are hot and stiff when warmed up.

I am not losing any coolant at all, as far as I can tell. After it cools down, the coolant is at the same level as when I started it cold.

When it is not overheating, heater blows out really hot air. When it starts to overheat, heater is blowing out cold air.

Both fans appear to be running when it gets past the straight up and down mark. (Of course, I can only check this when idling)

Car "normally" runs just shy of the straight up and down mark.

After replacing all those items, I drove it for about 5 or 6 miles, and it never moved above the normal spot. Then, all of the sudden, it jumps about 1/4 of the way to the next mark. Stays there for a minute or two, then jumps up to the next mark. Repeat a few times, until it is almost to the red. By that time, I'm back in my drive way. Have repeated this several times.

This was on level, and mostly straight country roads. Speed averaged about 45 or so, but in a few spots, I got it up to 60 to see if it would overheat. Made 4 or 5 stops, with turns.

I can't feel all of the radiator, but the parts that I have felt have all felt hot.

The bleeder line to the top of the reservoir tank is not clogged. When warmed up, it spits out coolant. Not in a steady stream, but in bursts.

I find it very odd that it would run steady without overheating, then suddenly jump up and start overheating. I did not run the car very hard.

Once, when the heat gauge jumped up, I put it in neutral and revved the engine to about 4k rpm, and it started dropping back down.

When cold, the upper radiator hose seems like there isn't any fluid in it. I am not in any way, shape, or form a mechanic, but it acts almost like the radiator is only 1/2 full or something. (May the engineer who put in a radiator without a cap spend all of the afterlife working on this car.)

When the engine is warmed up, and running, there doesn't seem to be any "bubbles" in the overflow tank.

I have not done the CO test on the fluid yet, and I haven't done any compression tests, as I don't have anything to test compression. I have not done a cooling system pressure test, because I do not have the equipment.

Any ideas? I'm out of work right now, and money is tight, so I have to spend the absolute minimum. Believe me, when I was working, I just took it to my mechanic and said "fix it". LOL

It's almost like it is getting an air blockage that can't be cleared in the cooling system. I would have thought that if it was a bad head gasket, I'd have to add coolant to the system. Could I possibly have gotten a bad thermostat? (It can't be backwards, it only fits one way.)

Let me know if this isn't enough detail, or if you have any questions. I'm hoping someone will be able to help me out. I guess I'll go tomorrow and get the CO tester for the coolant. I could be wrong, but I don't get the feeling that it is the head gaskets.


not enough details ...


ok .. i'm kidding ...

based on the highlighted paragraph, i suspect the cooling system is NOT full, or the water pump is not working or the thermostat is not working or is on backwards.

if it was the head gasket, the heater would not be affected until the coolant level dropped.




.
 

Last edited by stomper; 06-09-2010 at 10:59 PM.
  #3  
Old 06-12-2010, 09:58 AM
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I have the same problem with mine 98 deville I would not waste time on doing the test just had coolant and pressure test done to mine and all the guys told me was everything working like it suppose to pressure hold fine and no gasses in coolant don't know what it is but bring it back when it ran hot or leave it here for 3 day so we can do more testes.

Not sure what the whole thing with bubble in tank, my lines are clear no blockage i do have bubble in the tank after in warm up but i thought this was normal i check my with car when it warm up it bubble and when it got hot it came spitting out. this is what mine doing as well small little bubble before it get warm

I thinking it also air in the coolant, everything i saw on here i tried and still run hot after 40 min to 1 hour I have replace radi, fans, water pump, top, and thermostat 3 times took off the bleeder bolt side of upper hose and clean that as well, cant find any answer but head gasket which i tested for gas 3 times and took to shop to confirm my result block good

i hoping to find answer soon so i can post it been 2 month already

oh when mine overheat coolant flow out overfill hose only when overheating beside that i don't lose any coolant, i making progress it something small i know it, when i first started it was gurgling in tank and spitting out now it just a little stream of coolant coming out of overfill hose and no noise
 
  #4  
Old 06-14-2010, 04:26 PM
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i had the same experiences you had and fixed what you did. the more i drove it the more the head gaskets became the culprit. My hoses where also very hard when it was warmed up but was full of air not coolant. i knew this because the very bottom of the Top hose was hotter than the top part of the hose. Check to see if the hose feels the same temp from top to bottom. Another thing you may want to check is if your fans are kicking on. I also didnt have any coolant in the oil or vise versa just air was getting into the coolant. and after the car sat for awhile it would cool off and be fine. like i said i had the same issues but the more i drove it the whole in the gasket must have gotten worse and i had white smoke out the exhaust. heres a link to view what my gaskets looked like on a 65k engine.http://www.cardomain.com/ride/3193930 scroll down 3/4 of the page to see the gaskets. but like Stomper pointed out if the heater blows out cold air when warmed up that means coolant is low. Which means its leaking into engine if you dont spot any leaks on the ground or any where else. which is what mine was doing, hence the air in my hoses. So try to do a bit more trouble shooting and Get back to us if you find out more.
 
  #5  
Old 06-24-2010, 10:58 AM
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Update:

I had a mechanic friend of mine check out the car. Head gasket (or the head) is toast between cylinders 2, 4, and 6. The coolant was apparently being forced from the radiator into the overflow, which was causing it to look like it was not using coolant.

The coolant going into the cylinders was causing the P0300 errors as near as we can determine.

Because I will NOT be redoing the heads, I am going to try K&W's "Nanotechnology" (following all directions EXACTLY). I only need this car to last for another year, so it's worth $20 to just give it a try. I will let everyone know the results, which should be in several days.
 
  #6  
Old 06-25-2010, 08:12 AM
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Did your pass the block fluid test im have same problem pass block and pressure test was thinking about trying s&w or the blue magic suff
 
  #7  
Old 06-27-2010, 11:59 AM
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most likely its the head gasket thats bad. but the gaskets are not all aluminum so any liquid magic stuff probly wont help since the compression in the cylinders will just push it into the overflow and possibly plug up other thing like heater core, radiator, etc.. so good luck and let us know what ends up happening. If things work for you this may help others who want a temp fix till they get a NEW engine or new car.
 
  #8  
Old 06-27-2010, 12:15 PM
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Originally Posted by samdun124 View Post
Did you pass the block fluid test im have same problem pass block and pressure test was thinking about trying s&w or the blue magic suff
most of the time if the head gaskets are going bad you will still pass pressure tests. they usually check for compression and if it falls in the right range it will pass even if the gaskets are failing.

My seville when i bought it had just got a used 60k engine installed and passed pressure test and so the engine was sold and installed in my car and 10k later the gaskets failed. By looking at these pics i dont think a pressure test wouldve passed but it did. and i dont think that 10k would cause this to happen that fast. lol



 

Last edited by 92_Daddylac; 06-27-2010 at 12:18 PM.
  #9  
Old 06-28-2010, 02:43 PM
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I just test drove my 98 deville after adding K&W nanotech i did not follow the part where it said to pull plug and deactivate zone and fuel for that zone did not know how to proceed with this process i flush it twice and mix 3 qt of water run for 25 min and drain and i let it sit for 2 day put flush and refill with 5050 drove for 2 hour today i live in texas the temp today is 99 deg it did not ran hour after dropping little girl off at day care at noon drove 30 to my wife job still around 217-219 went to get her some lunch and came back it was at 226 the hottest it got was 233 only 235 for a second but drop back down this stuff work from what i can tell might give it another treatment this weekend but before it would get hot and hotter i can see a major improvement with this stuff
 
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