VS Getting hot - electrical problem?

[MR.HG]

hi, i have a VS series 2 Berlina and just recently had some work done and from time to time the temp goes over 3/4 and the light/warning beep comes on. Its got a new radiator,cap,thermostat,full flush, heads shaved & new head gaskets,manifold gaskets etc and the thermos are working fine. all the work was done by a reputable mechanic, the only thing i can think of is like maybe a sensor or something but really have no idea, anyone?

[VR_Acclaim]

My vp done the same thing with head work, I ran a top notch coolant and a Craig Davis thermo switch and a cooler thermo stat, run ur thermo on straight power and see if the temp comes down, if not it could be ur gauge, or the temp sender, mine was the sensor

[djvass]

Do you get any fault codes?

[fonzo]

HA! ive owned my vs for 2 years and replaced every cooling peice that i can. hoses. about 4 or 5 thermostats. radiator. radiator cap all hoses to overflow bottle both coolant temp sensors just incase. replaced the gauge. heater hoses. heater tap. u name it...ive changd it and it still does it.

[hako]

When the warning beep comes on, are both fans running...and under what conditions does this occur, like uphill, traffic? Does the engine ever actually boil with coolant ejected from the overflow tank?

[db_notso]

+1 sensor
OR stuck thermostat as that was alot of work done could be some shitte stuck in it ( but not likely if was reputable mechanic)
speaking of which did you ask the reputable mechanic too fix his work
?
he should under australian law if its paid with recipet from a buisiness!~

[MR.HG]

yea guys got to the bottom of it last night, was the brand new thermostat wasnt opening properly, cut the guts out of it (spring n crap) works fine now.Both speeds of the fan were working fine and thankfully i live pretty close to everything so i only really noticed it a few times. It would mainly occur after i stop driving, run in to a shop to grab something then come back start up the car and the warning light would almost instantly come on same as the thermos and temp guage straight to 3/4+ bottom hose was cool and top hose boiling hot. so the radiator is doing its thing, plenty of flow so pump is fine...was a process of elimination.

[Brett_jjj]

You should get another new thermostat for it as soon as you can,the engine needs a proper working thermostat to keep it running at its operating temperature,otherwise it will run too cold which causes engine wear,poor fuel economy and bad running.Basically the ECU thinks the engine is cold and makes it run richer than it should.Years ago,you could throw the thermostat away and not run one at all.A lot of 1980's cars with the automatic chokes that ran off the engine coolant temp put a stop to that,if the coolant was too cold,the choke stayed on,and its basically the same today still with EFI and engine management.

[Jacko84]

^^^^^^+1 car runs alot better with correct thermostat working properly

[MR.HG]

need a thermostat in Queensland? thermostats only really effective in the first 5 mins of driving, right?. so long as the temp gauge sits on 1/4-1/2 cant see there being a 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_1]

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

[bpefi]

If you have the radiator out - check out the rubbish buildup in the a/c condenser - I put up with an overheating problem for years until one day I had the radiator out & tried to see through the condenser - gave it a huge blast out with air & fixed the problem