temp spiking/ coolant leak? need help!!

davito

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I have searched a lot on this over heating issue. I just want to narrow down and pinpoint the problem. If air pockets in the cooling system are causing the sudden temp spikes would the car steam at all-since it is more of a false reading caused by an air pocket. If there is coolant under the engine cover would this indicate a leak or would the excessive pressure of overheating cause some coolant to come out onto the engine?
 
any over-pressure would likely cause the cap on the degas bottle to pop (which holds 7psi). long before that coolant should come out the over flow tube on the degas bottle and simply spill the coolant on the ground.

if your car is randomly 'overheating' then it's likely something simple:
- make sure your coolant is at the right level
- bleed the system properly to ensure no air is trapped
- the thermostat. It's cheap and know to be an issue on pre-03 LSes. This also means that you bleed the system
- check the degas bottle for cracks - another know issue. It prevents the system from pressurizing and the coolant boils sooner than it should.
 
where is the degas top? Quik-thanks for the speedy help-good luck on your sc kit! Your car and this site made me get my LS
 
the degas bottle is rigth up on the firewall driver side - the coolant fill cap.

thanx for your support...
 
would getting the coolant system flushed take care of the air bubble problem? the coolant needs to be flushed anyway. Would they get all of the air out of the system or would I still need to bleed the system>
 
Quik LS said:
the degas bottle is rigth up on the firewall driver side - the coolant fill cap.

thanx for your support...

How hard is it to replace the Degas bottle. I have a pretty good feeling that that is the problem Im having. I replaced the thermostat a while back and it fixed the problem for a while, probably because i topped up the antifreeze too. But now every couple weeks to a month it starts to heat up again. And to fix it all i have to do is add more antifreeze and then its been good for another couple weeks.
 
and the spike is NOT a false reading. Typically it means the pocket is somewhere in the cylinder head and causing the cylinder head temperature sensor to see an overheat condition....NOT good.
 
Roadwarrior50 said:
How hard is it to replace the Degas bottle. I have a pretty good feeling that that is the problem Im having. I replaced the thermostat a while back and it fixed the problem for a while, probably because i topped up the antifreeze too. But now every couple weeks to a month it starts to heat up again. And to fix it all i have to do is add more antifreeze and then its been good for another couple weeks.

not hard....


PM me your e-mail address and I'll send you the instructions....
 
beaups-what does it mean if it is in the cylinder head? you posted not good-did you have a bad experience??
 
CHT (Cylinder head temperature) sensor is one of the primary sensors used to determine engine temperature.

it's screwed into the head right between cylinder #3 and #4.....
 
sorry for all of the questions but:

if it was the head temp sensor would it actually be getting that hot? would it steam or does that just prove i have fluid coming out somewhere?

tonight i drove it about 12 miles and at normal running temp the heater blew ice cold air? Thermostat?

I dont know what to replace first!!
 
I looked above and I didnt see you saying that you have a leak, do you have coolant spilling out anywhere? If yes, where is it coming out at. Also If you have air in your system, you should be able to fill it in the cap by the thermostat. I also saw you have done alot of searching. If so you will see the overflow/degas bottle always gets hairline cracks on the bottom, causing the engine to overheat every once in a while or when you get low on fluid from it spillin out by your drivers front tire. also you will have see the thermostat is also a common issue, its cheap and easy to replace so do this anyways. next you also saw that if you dont fill it from the fill cap on top of the engine, you probably have an air pocket. if none of these are your problems then check your fans and pump(hydraulic and expensive pain in the @ss), check your sensors(like quik was telling you) If its not any of these good luck!
 
IIRC there are 2 temperature sensors in the LS. A standard coolant temperature sensor and a cylinder head temperature sensor. As I understand it, the temp gauge in your car is "normally" driven by the coolant temp sensor. However the CHT is normally active and feeding information back to the PCM to adjust timing, etc. If the CHT begins to see overheat, it causes the fast "spike" in the temp gauge...and can also cause a check engine light. Overheating heads cause all sorts of problems...i.e. warping, gasket failure, etc.

My only point is that it seems whenever this issue comes up people refer to it as a "false" reading. It's not false at all.
 
davito said:
sorry for all of the questions but:

if it was the head temp sensor would it actually be getting that hot? would it steam or does that just prove i have fluid coming out somewhere?

tonight i drove it about 12 miles and at normal running temp the heater blew ice cold air? Thermostat?

I dont know what to replace first!!


the old days of the system over-pressurizing and blowing steam all over the place does not happen very often anymore.

the cabin heater is feed from a tap off the upper rad hose, and then circulated threw the cabin by an electrical aux pump.

if the thermostat is stuck closed - the car will eventually overheat - while the rad stays cold, and the cabin circulates cold - so that would be my first bet....
 

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