VS Getting hot - electrical problem?

[Brett_jjj]

They constantly regulate the coolant temp,youve only gotta see what happens if you remove them,the engine sits at cold.Even in hotter areas.It might warm up a bit sitting in traffic,or when its hot outside in the day,but what about at night,or when its raining?Its best to run one anyway,if its still overheating with a thermostat in it,then theres something else wrong.

 

[MR.HG]

still getting hot without the thermostat ....im going to swap the thermos and replace the pump today and i will pop in a new thermostat ....may as well change both sensors while im at it heh...not much else left to do im really running out of options...cant be head gasket..just did those

 

[hako]

It is possible to fit the thermostat wrong way up - then the wax element that is supposed to be on the hot side is on the cold side - it will open eventually but not till really hot. If you run without a thermostat you can overheat the engine as the thermostat also restricts the flow of coolant ensuring that proper scavenging of coolant from the back of the block occurs.

 

[MR.HG]

It is possible to fit the thermostat wrong way up - then the wax element that is supposed to be on the hot side is on the cold side - it will open eventually but not till really hot. If you run without a thermostat you can overheat the engine as the thermostat also restricts the flow of coolant ensuring that proper scavenging of coolant from the back of the block occurs.

i have the thermostat still in just the guts removed so the flow is still restricted somewhat

 

[Brett_jjj]

still getting hot without the thermostat ....im going to swap the thermos and replace the pump today and i will pop in a new thermostat ....may as well change both sensors while im at it heh...not much else left to do im really running out of options...cant be head gasket..just did those

Also check the bottom radiator hose when the engine is reved up.Ive seen them collapse in or suck in from the suction of the water pump which then stops the coolant getting through.Most lower radiator hoses run a coil spring through them to stop this from happening.Ive noticed at lot of the commodore lower hoses dont have the spring in them,so if they get old and weak ,theres a chance the above could probably happen.

 

[VS_Pete]

Sorry didn`t read properly

 

[Brett_jjj]

Ive probably done 20 radiator flushes etc now on these cars (V6), and I never worry about bleeding them,and Ive never had a problem with trapped air or overheating.I used the bleeder screw a couple of times when I first got my car,but I then read in the workshop manuals that you dont need to use the bleeder unless using some special holden tool,so I stopped worrying about bleeding it and Ive not had one problem.I always make sure I fill the radiator with the car facing uphill,that might have something to do with it.Ever since I was a young bloke Ive always made sure the front of the car is higher than the back when refilling the cooling system,its common sense.In saying this,theres lots of blokes on here who have, or have had trouble with them,I dont know why,maybe they fill the cooling system with the front of the car lower than the rear,its about the only thing I can think of that would cause lots of air to be trapped in the cooling system.

 

[MR.HG]

thanks brett, as soon as the missus gets home i will take a look

 

[Ghosty85]

I'd suggest leaving it to cool... lol

 

[MR.HG]

finally!! found the problem! water pump had absolutely no fins left on the impeller, amazing it was even circulating at all. pics coming soon you wont believe how bad the pump was. these are some valuable points i learned throughout this experience so ill share them here

Removing the guts out of the thermostat was a good method for eliminating thermostat as a problem, so i will put a new one in soon.
Temp sensors serve 2 purposes.....
1) tells the thermo fans when to engage ( and if your fans engage at half temp then your sensor is doing its job )
2) Tells the computer how hot the engine is operating at and controls fuel to air mixture ( if the car runs too cold the sensor will tell the ecu to run a bit richer - like a choke)

Jacking up the front of the car to put in the coolant is a great idea also (had a 4l air pocket as well) and ensure proper bleeding of air from the cooling system at operating temperature.

flush the radiator to test if it has any blockages...the radiator should not be able to fill up if it is not connected to the car. and the flow out of the radiator needs to be the same as the flow going in . block the bottom hose off first and fill it up then release the bottom. if you have a good flow your radiator is fine

Thermos can either suck or blow....make sure it is sucking air through the radiator and not blowing through

if everything above is fine and your still having troubles after replacing most of these components then it is more than likely that your head gasket is blown. a test on the water will confirm if this is a problem and most mechanics perform this test for around the $40 mark