QuestionQUESTION: My 1999 Cadiliac STS with northstar engine, i just got it and it seemed to run a little warmer than it should and heat dont work...changed the t-stat and burped the coolant systemby the purge tank cap and then while sitting in the car and reving the engine at around 2000rpms then Bam the starts to work and the temp goes to normal .... keep in mind there r no leaks holding pressureand no oil coolant mixure... and been driving it for a whole day and then all of a sudden while driving down the road the heat stopped working and imidiatly the car began to run warmer than supposed too... i put the right coolant in as well....so i get to the house and think that it just needs burped moreand tried that a couple of times and nothing so i then went to pull it around to park it and suddenly it seemed like somthing in the heater blower kicked on stronger and i instantly had great great heat and engine temp dropped to normal almost instantly... so then i went to drive it again to check it out and no more than a half a block down the road all over again heat quit blowing hot air and went to cold and engine started to run hotter .... what in the world could it b???? i havent checked the lines to c if one is hot and one is cold with the heater core and the radiator... i think that i checked the radiator hosses and they were both hot and but i will check the heater core lines to see if both r hot and not clogged up..... please help !!! i really wanted this car and finally got it and its been problems with the heater and engine since i had gotten it, the guy i got it from said he never had this problem and that the waterpump was replaced like last year i did not put the pellets in when i changed the thermastat but am gonna try to get some tomm to put in it... please help ASAP thank you for ur time and assistance in this matter....
ANSWER: Hello,
One of my first thoughts is the radiator is spitting out because the electric cooling fan is not coming on. Just my first thought. To check--turn on high blower and put on A/C or defrost with key on engine not running. If fan does not start within a minute or so, you need to find out why.
Could be a bad fan or possibly a relay. Low speeds you need the fan to cool radiator.
Be warned and you need to consider the car's history as to why it had a water pump changed a year before. The minute you pass the 3/4 mark on temp gauge, the aluminum engine is self-destructing. This engine cannot be run hot!!!! If in the hot area, if not shut down immediately, it is head gasket or block time, meaning you need to get dinged by Cadillac for $5k for a new engine because there are not any good engines available in the junk yards. A majority of them were over heated and are junk!
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QUESTION: if fans r working correctly then what should i look at ??? thank you for ur help...
ANSWER: Hello,
If the fans are working, then you have to consider a circulation issue. These cooling systems had issues when the engine got more miles on it, anti freeze was not changed every 3 years/36,000 miles. It was and has been common for these systems not to be maintained because there were no leaks.
You state the water pump was changed a year ago. That's fine, but why? Were they chasing an over heating problem back then? Impellers broke off of some of these water pumps. Was it leaking and had been run hot at that time? Was the system back flushed at the time of the replacement of the water pump, or was anti-freeze/coolant only added. I realize you can't give me these answers and maybe the previous owner is telling you the truth and maybe not.
I am very cynical and don't trust anything I am told.
If the fans are working, you will need to do your own maintenance and you will need to start now before it is too late and you go past the point of no return driving the engine hot.
The first thing you know is that you really know nothing about the history of the car. You don't know if any type of coolant leak sealant was put in the vehicle. You don't know if green coolant was used instead of red not designed to mix with it.
Stay away from a dealer. You pay far too much for nothing that you or a service center can't do.
Have the system pressure tested including the radiator cap.
If everything is good there, back flush the cooling system. If you still have problems, price the cost of boiling the radiator out compared to a new one, because you will be dealing with a circulation problem.
Worst case after doing all this, I have had people tell me the water pump was previously changed and it would be removed again, only to find a whole lot of crud and once removed, never had a problem again, but hopefully, you will find the problem before then and DON'T remove the water pump. Try the suggestions in order.
These aluminum engines can be very problematic dealing with an overheating problem and it is fatal for the engine to overheat!
Many think they can drive that last 1/2 mile home and they simply can't without having consequential results. These are a great engine with good mileage and power, but overheating is their Achilles' heel.
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QUESTION: you r totaly right i dont know anything about it really.... there was very clean looking green antifreeze in it when i got it...the dash says somthing about could be ice when the engine temp starts rising what does that me ? is it sensing that it has poor cirulation?
AnswerHello,
Thanks for your wonderful accolades! I bet the service manual doesn't tell you to clean the crud or gasket material out. (LOL) I know these things because I have lived them and real life experience beats academia every time!
Glad I could Help.
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