: Northstar overheating causes



bentley
08-05-07, 11:18 AM
Someone who works on Northstar engines said the overheating problem on my 1994 Cadillac STS is due to one of 3 problems – a bad water pump, bad head gaskets, or a bum thermostat. I am looking for second opinions because he thought it probably was the head gaskets and that the cost would be over two thousand bucks. The car has overheated dozens of times over the last few months but not predictably. That is, I might drive under 10 miles and the thing will overheat – or I can drive many more miles than 10 without it overheating at all. Sometimes there will be a big puddle under the car when I go out in the morning – sometimes not. I add quite a bit of water to the overflow when this happens. I changed the thermostat myself a few weeks ago but that didn’t seem to make any difference. Do these symptoms give anyone an idea as to what the real problems is? Also, how can one tell whether the head gaskets are gone or whether the water pump is the culprit? Thanks very much for any observations.

JimD
08-05-07, 12:08 PM
[FONT=Times New Roman][SIZE=3]....Sometimes there will be a big puddle under the car when I go out in the morning – sometimes not. I add quite a bit of water to the overflow when this happens.

My first step would be to locate and repair the external leak. Possibilities include radiator end tanks, hoses, water pump cartridge seals, water pump cover seal among others.

Ranger
08-05-07, 03:03 PM
Would I be correct in assuming that the puddle is from the overflow? Check the purge line, belt tensioner & surge tank cap, any of which could cause an overheat situation. If all that checks out, have a cylinder pressure test done or the coolant tested for exhaust gases. If you see bubbles in the surge tank when you start the engine (cold), no need to go any further. Gaskets are gone.

misfit6794
08-05-07, 09:11 PM
Yup, what ranger said. 2000 is actually pretty cheap to do the headgaskets.

zonie77
08-05-07, 11:33 PM
First, there are literally hundreds of posts on this.

Second, the symptoms are classic head gaskets on a Northstar. The old rule of coolant in the oil is meaningless on newer engines, and it never was that accurate previously.

Third, the high cost is because they crammed a DOHC V8 into a car in FWD configuration. All that extra room you get because of FWD is taken from the engine compartment. Now you have to pay for the extra labor to work on it.

99_WHITE_STS
08-06-07, 03:48 PM
My guess would be the head gaskets. From all the info on this site, I have come up with the tests that I feel are in correct order that will point to this being the problem. I have just nailed down my overheat problem as being caused by the head gaskets leaking. I know I am going to get alot of controversy on what my approach is going to be, but in my situation, my first step to at least temporarily arrest the problem, is trying one of the stop leak products that is on the market, more than likely, Thermagasket. I am planning to start my own thread, detailing the progress of using this product. Additionally, I have also lined up a mechanic that is willing to engage in the task of doing the mechanical repair, if all else fails.
Again, I would surmise that if there are no other coolant leaks in the system, other than the overflow, that is the problem with yours. I would be more than happy to assist my knowledge, as far as pinpointing the problem. I am new on this site, but have researched the Northstar overheating problems extently, so if there is some advise for me regarding posting and using this site, feel free to let me know.
Thanks, Jim

Ranger
08-06-07, 08:10 PM
Jim, save yourself the trouble. Do a search for "Thermosgasket" by Rfishing. It is lengthy. I hate to ruin the end of a good story, but bottom line is repairs in a bottle do not work.

jadcock
08-06-07, 09:15 PM
Jim, welcome to the site! Experience is mixed with those types of products, but at this point, what do you really have to lose? Not much in my estimation -- you're still in for a head gasket job. The only possible downside I could see is that it could temporarily work, and then put off a more catastrophic failure until further down the road, so to speak. I don't think I'd ever trust such a repair, but then again, if it works and your drive cycle is pretty regular (like, just to work and back), you may have saved a boat load of money.

Ultimately, the best repair is a mechanical repair, but it'll be interesting to see what your experiences are. Looks like you've done your research and have your ducks in a row if it doesn't work out. But compared to a repair of over $1000, $10 on a chance product is money well spent, whether it works or not, in my opinion.

99_WHITE_STS
08-06-07, 09:20 PM
Jim, save yourself the trouble. Do a search for "Thermosgasket" by Rfishing. It is lengthy. I hate to ruin the end of a good story, but bottom line is repairs in a bottle do not work.

I really appreciate the words of advise and caution RANGER, and that would typically be my approach. I have been unable to work ever since a failed back surgery in Aug. 2004, and have been "fighting" with Social Security for disability ever since then. I have permanent nerve damage in my back, and have to take morphine on a daily basis. If I didn't try the Thermagasket, the car would just have to sit , until I get approved, supposedly some time in 08. This whole ordeal has ruined my credit to the point that even if I was willing to pay the money to fix it, I couldn't even get a loan. My approach to using the Thermagasket is not to camoflouge the problem and dump it. It would be to buy time until I can fix it correctly.
I've read the complete rfishing post, inside and out to the point of confusion, but it stood out to me, that your comments throughout the entire episode, always seemed to be good advice. The main participates in that post were "all over the place" attempting to diagnose their over overheating problems, and I found with a few simple procedures, it just isn't that hard.
Again, I appreciate your advise and input anytime, but I have really never heard of any negative effects of using the Thermagasket, that affected making the correct mechanical repairs in the future. If anyone would know of adverse effects, please let me know.

Ranger
08-06-07, 09:48 PM
My approach to using the Thermagasket is not to camoflouge the problem and dump it. It would be to buy time until I can fix it correctly.
That it may do. Best of luck to you.

bentley
08-16-07, 10:01 AM
Thank you all for your comments. They were very helpful and interesting. I had a mechanic out to do some testing. He examined the exhaust, listened to the water pump with some sort of device, and did some other tests. He concluded that problem probably was due to the radiator. I am having that and some hoses replaced. I hope that is the real culprit and will let all know how the situation turned out.

Bentley

Norman93Eldorado
08-19-07, 06:08 PM
Our 1993 Eldorado had a blocked radiator. The dealer said that there was almost no flow of coolant through the radiator.

99_WHITE_STS
08-20-07, 07:32 AM
Thank you all for your comments. They were very helpful and interesting. I had a mechanic out to do some testing. He examined the exhaust, listened to the water pump with some sort of device, and did some other tests. He concluded that problem probably was due to the radiator. I am having that and some hoses replaced. I hope that is the real culprit and will let all know how the situation turned out.

Bentley

I think I would proceed with caution. Using the word "probably" tells me that he's guessing. When there are definitive ways to do testing and be a 100% sure, looking, listening and guessing can be expensive!
I would have him pressurize the cylinders and see if air shows up in the coolant pressure tank. It took me an hour to check all 8 cylinders, and I had 3 leaking. If that test is negative, have a radiator shop use an infrared thermometer to check the radiator. Tests are less expensive than needless repairs.
In contrast to my prior post, the "mechanic in a bottle" has disappeared from my list of temporary repairs. It appears as if I am getting some financial assistance from an extended warranty company, but I am having a hard time convincing them that the necessary thread repair, is part of the covered head gasket repair.
Good luck with your problem. Keep us posted !:thumbsup:

kaykirk
09-07-07, 12:43 PM
I really appreciate the words of advise and caution RANGER, and that would typically be my approach. I have been unable to work ever since a failed back surgery in Aug. 2004, and have been "fighting" with Social Security for disability ever since then. I have permanent nerve damage in my back, and have to take morphine on a daily basis. If I didn't try the Thermagasket, the car would just have to sit , until I get approved, supposedly some time in 08. This whole ordeal has ruined my credit to the point that even if I was willing to pay the money to fix it, I couldn't even get a loan. My approach to using the Thermagasket is not to camoflouge the problem and dump it. It would be to buy time until I can fix it correctly.

Again, I appreciate your advise and input anytime, but I have really never heard of any negative effects of using the Thermagasket, that affected making the correct mechanical repairs in the future. If anyone would know of adverse effects, please let me know.

99WHITESTS, I can aprreciate where you are coming from and I am sorry to hear of your troubles. My hubby had a failed back surgery 22 years ago. He is medicated daily - has good days and bad days.

Now to your car...I want to tell you the bottled approach will probably not work and it can damage other parts to your car. I have a 97 Olds Aurora, with the Northstar V8 4.0 engine. I blew the head gasket earlier this year. we tried the "miracle in a bottle" approach, but it did not work. we also tried this because the hubby lost his job and we could not afford the repair bill. When we finally decided to get it repaired, we could not find any reputable mechanic to do it (not even the dealer!). I ended up replacing the engine with a low mileage used engine. The mechanic who dropped the engine for me had to replace the overflow tank, water pump (which was just replaced 1 month prior to the blown head gasket) of course the thermostat, but we knew that would need to be replaced. we had replaced the radiator a couple years ago, so my husband was very careful to flush it well so as not to let that stuff sit in there, and we may need to replace it again! we also may need to replace the catalytic converter due to coolant blown thru (so probably not the "bottled" stuff)

I am new here and will look forward to hearing how you come out (or came out). Best of Luck