After taking my car to Sewell Cadillac due to a check engine light, they said it was my intake gaskets, andI agreed to replace them, next day they go to fix them, andI mention that my car was using a litle bit of coolant and manager replies " that could be bad, maybe a blown head gasket,"next day they tell meI have a blown head. I get it home, and it leaking coolant everywhere.I first replaced the surge tank which had been broken at Sewell after im guessing someone leaned on it. I also replaced the thermostat. Next day i drive it around, it was doing fine at 196-205 degrees and shoots upto 248 degrees, which waswhen i turned off the car. It took1 hour and 20 mins to cool down to 200 degrees. I replaced water pump anda few hoses. Car is driving good, and stays between 190-224 sometimes going up to 230 degrees. Is 230 ok?? also if i had a blown head what signs would i see?? No white smoke, no bad oil, no loss of power? Is Northstar engine hiding it??? any help is a huge thanks!!! this has been ongoing for 3.5 weeks, ready to know if its ok
Thanks!

 

You will use coolant when the intake gaskets are bad as well. It is really hard to judge gasket failure with the way the engine runs. I mean you have a lot of horsepower here and that can hide a lot of problems. I'm not saying you have another issue it's just that the car may seem to be running fine.

Normal range for the Northstar as per the owners manual is180 to 200. As for the 230 well I wouldn't get that concerned if you see 230 when stopped or idling, regular driving it should come down. I believe the warning systems kick in at 248 which is what you saw. I also suggest that your coolant was low because the surge tank was broken and leaking and maybe the water pump too. Do you have any leaks now? Also what climate do you live in? Northstars do run hotter than most engines you might be used to. Make sure your cooling fans are operational too. I think the dealer may have spooked you but it definitely a situation to monitor. Keep an eye on your coolant level over the next little while as well.

 

Today i drove it about 100 miles, is stayed between 190-208 then spiked on the way home to 230, then 232, then 235, i quickly steped on the gas as i was told that this would increase water through my system, and within 15 seconds the 235 droped to 196 degrees. Im thinking perhaps my censor is bad, because thats a huge temp drop in a matter of seconds. Ive had my water pump, surge tank, and thermostat replaced, and no leaks are visible at this point. Im just concerned about the temp raising to 235 for no reason. does this sound like a bad censor problem, or is it possible for a system to cool off that quickly? As for the fans, i tested them and the first one is kicking on at 224 degrees, so im guessing they are working fine. The car is in Texas, but it was around 60 degrees all day.
Thanks forreplying!

 

Coolant sensor bad? Could happen, but when it goes bad, you got
starting/drive-ability issues as the ECM is mixing fuel based on the
coolant temp sensor? But easy to test, compare with a thermometer.
The jumps in temp describe coolant NOT flowing properly.

I have seen and heard some weird things with people drivng the N*,
seems to be non-forgiving to the following items.
Things to look for when there is NO LOSS of coolant,
and running hot:


- bottom RAD hose collapses, no structural spring inside,
- thermostat is on backwards,
- thermostat is sticky. read FAQ on Dex-CoL,
- radiator is plugged. read FAQ on Dex-Cool ,
- running 100% water instead of 50/50 coolant mix,

And the best for last ....

- the water pump has the impeller installed BACKWARDS
(It happens more often that we all think and
to check, you gotta remove the water pump)

- now, imagine what happens if you got two or
three of these items at the same time

(If you are loosing coolant but cant see the leak, you are
most likely looking at a headgasket or worse . . The dealer
should have tested for that before putting a single wrench on
the engine. I be having it tested before anything is done)

whatever you do, make sure you refill with 50/50 mix
of coolant and distilled water and add the supplement.

FYI -

 

At 60 degrees your temp should be somewhere around 196. I'm not saying it's NOT the sensor, however sometimes a NEW installed thermostat can be bad.

 

Thanks to both of you! I will check the following items. Car so far is not loosing coolant. *knock on wood* Parts were baught from cadillac dealership, although we noticed the new water pump was uneven, and when we put it on.. it leaked. We filed it down, but perhaps there are problems with all the parts.. water pump & thermostat. we never really checked the radiator.

 

Has a pressure test been done? It is a very simple but very useful test. It is basically a hand-pump with a sensitive pressure gage that you attach to the surge reservoir and pressurize the system. It it leaks down over time, there is a leak. Some pin-holes won't leak until high pressure is reached.

Also, when you get the engine running while the gadget is attached, and you see the needle oscillating, that means that there is a "connection" between the cooland passages and the combustion chamber - bad news!

Gunning the car usually brings down temperatures; however, if there is restriction in the path of the coolant flow (collapsing hose or faulty, partially closed thermostat as previously suggested, or chunks of gunk, etc.) then that would explain the extent to which it works in your case. Have you also inspected the radiator for air flow? Leaves, bent fins?

 

I have not checked the radiator but i think thats the next step. For the past 3 weeks, my car has been fine, but today it went from 196 to 238, i steped on gas...went down, came back up 236, steped on gas, went down, came back up, then i pulled over. After about 10 mins, i unscrewed the surge tank lid, it was not hot, even at what my car shows 222 degrees. I have not lost any coolant. My car is driving hotter than its usual 196plus, but is staying 207plus. When i got home this evenng, my car showed 210 degrees for the coolant, once again i bare handed unscrewed the lid. Is it possible for me to even touch 210 degrees?? Or perhaps my censor is bad??? My fans kik on when there supposed too, so im not sre about thermostat..... These Northstars sure are picky

*Also i need an oil change but am about 200miles over, i wouldn't think this would have anything to do with temp??

 

At those temperatures the lower radiator hose should be sizzlin' hot. Is it?

 

last time i checked, plain distilled water boiled at 212F at sea level.
with added "coolants" the boiling point rises a significant amount.

i guess i didnt make something clear, but belagatyo has righfully eluded to it:
if the engine is at running temp or higher, you should not be able to grasp any of
the coolant system hoses or the rad-tanks/cap without an OUCH blasting from your lips,
unless the nerve endings on your hands have been damaged prior to the occassion.

if you can grasp the hoses, top or bottom, or the radiator tank without pain,
coolant IS NOT FLOWING ... touching the surge tank not applicable

i direct you to re-read what i posted about three replies back ...
the answer is there ...

except, i best add one more ---- CAVITATION --
water pumps do NOT pump liquids well in the presense of gases ...