Expert: Rob Painter - 6/7/2011

Question
QUESTION: my boyfriend and I just got a SLS cadillac, year 1998.  we got it, drove it for about 2hours, going thru mountains once, it overheated, but not too bad.. we've been driving with only water.  we took it to autozone, because it was a hot day once and that day it overheated passed the middle temperature.  that day it reached 270 degrees, and they told us it might be the cti sensor or the thermostat.  it's been about 4 weeks now, and two days ago, my father took the thermostat out and put 50/50 supertech antifreeze in it, we took it about maybe 1n miles, and the engine overheated, said engine hot and the engine shut itself off while it was in neutral..help is there anything that was wrong with it, i hope this didn't damage to the engine, because now the engine is idleing.  help, this is my boyfriends car, and so far, i feel like its my fault. but i know that driving with the car heated could cause damage to the heads, my only hope is that it didn't.  could you tell me wat the problem is/

ANSWER: Hello,

Boiling point with water and no pressure do to damage to cooling system at this time, engine destruction is imminent. If you got the engine to 270 degrees, you can bet there is engine destruction and you need more than head gaskets. I was not aware the gauge went that high because after 230 with anti-freeze severe damage is being done to the aluminum block and heads.
Once the hot light comes on, its all over. Its like the oil light. By the time the oil light comes on in the dash, you can bet the bottom end of the engine is gone!

Your question really makes no sense. You say the engine stalled with the hot light on. You then say the engine is now idling and you ask what is wrong?

From your description and as I said, I am not aware of the Cadillac gauge going to 270 and no mention of the hot light then, that engine is history.
All I can say is that I am glad you aren't my girlfriend driving my car.




http://www.autotheftexpert.com

---------- FOLLOW-UP ----------

QUESTION: hello, thanks for your help, sorry bout not being clear the first time, and to clear things up, i have not drove the car yet myself, i'm only the passenger. Anyways, we got the car, no antifreeze, only water.  Brought it back from Farmington NM, to Gallup NM, about a 2 hr trip.  Went uphill once halfway thru the trip, engine heated, passed the middle gauge temp.  but didn't get as far as the red line to where it would say engine hot.  
it's been about maybe 4 to 5 weeks since we had the car.  last week, while going into town, it was a pretty hot day, went about 15 to 20 miles, and the temperature heated to where the dash displayed for the first time saying engine hot.  reservior had boiling water, engine light came on.  we then took it to autozone, engine still seemed pretty good on top, no idling yet, nothing we noticed to be wrong except the boiling water.  so, they checked the car, went back to the computer to see wats up, they checked the codes they got, and results were it was the CTI SENSOR, or the THERMOSTAT.  Sadly, we didn't mention that we only had WATER IN THE RADIATOR, no ANTIFREEZE AT ALL. THE salesperson said that the engine did reach about 270 degrees.  a couple of days later, my dad took the thermostat out, didn't put it back in, put in the 50/50 supertech antifreeze, and we drove it later that day in the evening, after reaching about 10 miles, the temperature started rising, and dash flashed that the engine heated, we pulled over, turned around after cooling.  asked my dad to put the thermostat back in, he had to go get a new one, and after that the engine has been idling, lately theres been a bit of white smoke coming out of the exhaust.  the temp goes past the middle temperature after about 15 to 20 mins. of driving.  pretty sad, makes me worry.  so from this second question, could you please send me another answer of what might have actually happened, we both like the car very much, and i myself feel like its too late to prevent any damage.  is there anything i can do to get this fixed without paying so much.

Answer
Hello,

the engine I am afraid is beyond repair. White smoke- head gaskets or cracked block. Not the cause but the result from severe over heating. 90% or more junk yard engines have the same issue. The car is not worth the cost of $4k for a new engine and it will not be long before the engine quits all together. Don't stick any moremoney into it.