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Northstar overheating.


rvaddict

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:unsure: Well, it does over heat. I have a 1994 Seville SLS. The past three days, it ran fine the temp stays usually around 205 to 225 degrees. Yesterday it was 95 degrees outside and I let the car sit for about 20 minutes with the a/c running so my kids would not bake while I was standing outside having a chat. Then, the car started beeping and said "engine hot" and then "stop engine" and it shut itself down automatically. After it cooled off, I restarted and drove home -- no problem but you can bet I watched the temperature the whole way. Today, my wife was driving home with no traffic in front of her and the car suddenly overheated again, this time dumping a lot of coolant out the overflow at the radiator cap on the coolant reservoir. This time, I drove it home after it had cooled off, but it heated up real quick and I barely made it. I have heard that these cars have trouble with the head gasket going bad. Would this problem be indicative of that? At this point in the game would it be any help to add the coolant sealant from GM? How can I know it is not the head gasket? Do these cars have a normal thermostat like old cars have, and it is easy enough to replace to see if that is the issue? Help>? Suggestions? Thanks so much.

Adam

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Try not to jump to conclusions that it may be a head gasket before you diagnose what the problem is, its sort of like having open heart surgery as the result of a broken ankle. A number of things can cause this to happen:

1) a bad thermostat that is stuck closed or partially closed, if your problem is sudden, I would buy an OEM thermostat and seal, and replace it after checking for the obvious.

2) a slipping water pump belt because of the tensioner or the belt is bad

3) less than a 50/50 mix of coolant

4) a bad radiator/tank cap

5) low coolant

5a) cooling system pressure loss (cracked side tanks, hose leaks, etc)

5b) air in system, air bleed not working properly

5c) a clogged radiator

6) cooling fans not working properly or not working at all, check operation

7) drbris restricting air flow, leaves etc

8) a hose collapsing on the suction side of the water pump, spring rots out

9) a leaky head gasket

Report back what you find out

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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I printed your list and I will indeed report back! Thank you. BTW, is this site only for Northstar engines? Or, is this for all Cadillacs -- even (gulp) old ones? I have a few of them. Thanks.

Adam

Well, we seem to get a wide range of Cadillac questions. We have done a survey on "how old is your Caddy" that you might want to look up. Not to leave anyone out but the majority of discussion ranges from 1988 though the current.

Print my list again, I edited it a BUNCH of times, LOL

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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Hey Guy's

How is everyone?

RVaddict i had the same problem with my 94 STS There is a hollow bolt above the water pump with a hose connected to it. Take the hose off and start the engine. If coolant does not shoot out the bolt then you probably have a clog in the line that runs under the intake or in the bolt itself. In my case pieces of the hose broke off and cloggeg the hollow bolt.

Goog Luck

Jeff B)

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IF, it is a head gasket, sealant tabs will not help. They are only to prevent niusence leaks from porous castings and gaskets OTHER THAN head gaskets (pressures are way to high).

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A good radiator shop can test for exaust in the coolant. Also coolant in the exaust. These will tell you for sure if the head gasket (s) are bad. Good luck, the least expensive that I have found is $1300.00 to replace the gaskets and nothing else.

Ed

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Thanks to everyone for the responses. I checked the little hose that is the return back to the surge tank. It is flowing, not much, but is flowing. I back flushed it to make sure it was clear. I replaced the thermostat. I replaced the water pump belt. I flushed the system real well and found it to be relatively clean. No corrosion at all. I checked the spring in the lower radiator hose--perfect. I put in some K&W block sealer (just to see what would happen). According to the instructions, I let it idle for a long time. After 40 minutes, it overheated. That was yesterday. Today, I tried it again but this time I drove it instead. It drove around perfectly fine with almost constant 194 degree coolant for about 40 minutes. Then, all of a sudden, it overheated. It seems that is overheats due to loss of coolant, but I can not see any coolant leaking out anywhere. There is no steam out the tailpipe; no bubbles in the surge tank. The coolant just disappears. I will try the mechanic test next for exhaust in the coolant. I love the car and would hate to lose it. I'm getting tired, though.

Adam

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Might want to go to autozone and rent a coollant system pressurizer....At this point it should help you determine what your problem is.

A.J.

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Thats a good suggestion that acklac has, try pressurizing the system and see if it holds pressure. If it does, change your thermostat and check your cooling fans for intermittant operation and check your water pump belt and tensioner. Good Luck, Mike

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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Coolant doesn't "just disappear". Either it is leaking externally and evaporating before it drips to the ground or it is being burned slow enough so as not to steam out of the tail pipe.

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When you replaced the water pump belt, did you check to make sure the tensioner was free and not stuck? Are the cooling fan(s) operating at idle?

What is the concentration of your coolant? If you flushed the system, there might be less than 50/50 coolant concentration. You might want to check that with a tester.

If nothing conclusive results, rent a cooling system pressure tester and pressurize the system to 15 psi and look for the leak.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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rvaddict,

Follow Scotty's list. It tags many of the basic points that you need to check before you head down a path of major repair.

I just got through my worse-case scenario and replaced the head gaskets in my '97 Deville after a water pump belt shredded on me.

One simple check you might want to do is smell the surge tank when you remove the cap. If it has a hint of exhaust odor, you likely have a head gasket leak, but have it confirmed by a mechanic.

Two other possible tell-tale signs are a funky gray "mud" that will collect on the radiator cap gasket. Also, the coolant system may stay pressurized after the car has been shut off and has cooled down (e.g. overnight). If you remove the cap and hear air escaping, the coolant system is likey being "pumped up" from gases escaping at the leaking cylinder.

Good Luck and keep us posted on your findings.

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Stick with SCOTTY and all will be good!

I would definately pressurize the system.

Big Jay

Life is too short to grow up!

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Hello Again Everyone. Thanks for the responses. OK, here's what has happened so far. I have NOT pressurized the system yet, but will soon, especially after what happened today.

Here's the pattern. Does this sound familiar? Fill up coolant. Drive car for an hour, and all of the coolant is now gone. Must fill it up. While driving, car runs at about 204 degrees contantly even up hills. No sludge in the system, no smell, no indication that it is the head gasket. Today, however, I did see a leak I never noticed before. I still can't see where it is coming from. THERE IS WATER IN THE ENGINE VALLEY. LOTS OF WATER. There is a small space behind the power steering reservoir where you can shine a flash light and see the engine "valley". Low and behold! Coolant! Just sitting there. I played with this a while. If I start the car cold, I can see coolant leaking out underneath right in the middle where the exhaust crossover pipe is next to the transmission. If I drive the car for an hour (to where it runs out of coolant), it gets hot enough to cook out all of the coolant in the engine valley. I think the engine valley fills with coolant while the engine is still cold. There are two small coolant pipes that run behind the engine (along the firewall) and as far as I can tell, none of those fittings are leaking at all.

OK guys, is this the head gaskets? What else could fill the engine valley with coolant? This is such a nice car. So much money has been spent on all the other components. I can't believe this is happening....Will pump up system next.

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There is a pipe (air bleed) that goes from the water pump to the resouvior tank along side the front head, check to see if it has rusted through maybe you will get lucky. Mike

The only other thing to do is to pressurize the system and do a compression test, although if you have an external leak a compression test won't show much. I would pressurize the system.

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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