What I've been told isn't a problem (COOLING SYSYEM)

[Coro]

I've had the radiator cap replaced with a genuine holden one about 2 weeks ago with no effect on the overheating issue. I'd been putting in about a cup of water every week since I've noticed the cars temp rising. I've had the cooling system pressure tested just incase it could've been a head gasket but was fine, top radiator hose is also fine according to both mechanics I've seen.

I've got the car in to do a bypass of the heater core tomorrow so will update this in the next couple of days for future reference for others.

 

[Immortality]

A cup of water a week sounds like stuffed intake gaskets which is more than normal considering the age of the car.

I would suggest you continue to run the car with the dash in diagnostic mode showing coolant temp. Assuming you put in a standard thermostat you would expect the engine to be sitting around the 94°C temp when cruising and the thermofan to kick in at 104°C and drop the temps back into the high 90's before turning off.

When you had the work done on the coolant system if may not have been bled properly causing the erratic temp readings, once it's sorted itself out it may have settled down a bit. The fact that the temp gauge is sitting between 1/4 to 1/2 would suggest things are back to normal.

 

[AdventraAddict]

Thermostat !

 

[Coro]

but would the intake gaskets cause water/coolant to get inside passenger foot bed? Let's say it was the intake gaskets, how much of a mission would it be to get to them?

I think the system was bled correct, front of car was hoisted nose up with coolant/water mix poured into radiator cap until no bubbles were coming through. What the mechanic explained to me was that seeing as there was a leak that it was being replaced with air. He seems pretty certain that it's the heater core, ill get this bypass in tomorrow morning and monitor temp over the week to see if there's any movement.

 

[Coro]

Thermostat !

as mentioned in an earlier post, I've had the thermostat replaced with a genuine one yesterday. Though the temp didn't pass the 1/2 mark, it still rose which I stated in the OP that this has NEVER happened whether I'm at highway speeds or bumper to bumper on the hottest of summers days.

 

[kandlrex]

If there is wetness/coolant inside the car then it's your heater core causing the issue. It will need to be bled after any work to the cooling system.

These cars are pretty well known for overheating/coolant leaks... The best way to stay on top of it is to replace everything.

 

[AdventraAddict]

Sorry missed that ... Coolant on floor has to be heater core yes .... My bad didn't read all posts...

 

[kandlrex]

Parts are cheap for these and most mechanics have done alot of cooling system work on ecotecs, so shouldn't overcharge. Intake manifold gaskets are common and will cost a few hundred $ at least.

 

[Immortality]

Some movement of the gauge is normal, it moves a lot less with the AC on but it will still move. As I discovered myself when modifying stuff the gauge makes fairly large movements for only a small change in temp. The 1/4 mark been roughly 80° C and the half way mark about 92° C but you can confirm this yourself using the digital temp readout in diagnostic mode. The standard thermostat for the V6 engine is 195°F/91°C so once the engine is up to temp I would expect the gauge to sit roughly at the half way point on the gauge.

 

[Coro]

I'm just bypassing the heater core for the time being as I've spent quite a lot of money over the passed few months and being told it will be a $800+ job to replace the heater core.. I just can't deal with that at the moment. I'll most likely replace in the future but for the short term, bypassing seems to be the best way to go at this stage.

@immortality - As stated in previous replies, I've had the car for just under 5 years now and up until only a month ago there has been NO movement what so ever with the temp gauge. Whether bumper-bumper traffic on the hottest day in summer or not, the temp has always stayed at that mark. I understand it's possible for the gauge to fluctuate when no air is being forced into the radiator but when you've had a car for a considerable time, you get to know it in a way and any small changes do tend to lead to something wrong.. in my case it has.

For some reason I'm unable to get to the diagnostic setting on my dash, I've tried to press the mode+up button but only changes things relating to distance travelled, kms til distance, kms til empty, speedo alarm for going over 110 etc. Can't seem to pull up anything temp related.