Seriously annoying overheating problem

[Keggy]

ok so this is causing me nothing but headaches and money
i have a 95 v6 VS and it has a crazy over heating problem
its fine when driving around at a decent speed, sits at half way which is fine
but as soon as slow down to around 10ks or am stoped for a period of time. (doesn't take long)
the things starts to rise more and more. and the fan doesnt kick in till 1 notch aaway from red

i have replaced the following
Raditor
Water Pump
Sensor and Senders
Thermostat.

im seriously running out of idea. what could cause this sort of issue...

[The1]

is it using coolant or any other fluids? Could be a blockage somewhere in a pipe, otherwise take it to a radiator pro and get the system pressure tested, it could well be the head gaskets gone to.

The low speed fan should come on half and full speed should be on at three quarters.

edit also if you want to check the thermostat is working take it out and boil a jug of water and pop it in a cup and it should open up.

[hako]

You may be worrying about nothing - if the temp drops once the fan kicks in and the temp drops that means your cooling system is OK....my VS which I've owned for about 7 years now, goes to 1 notch from HOT before the fan comes on and then the temp drops quickly down to about 1/2. Many other Commodores act the same and I really think it is not the engine overheating but just that Ecotec engines are designed to run fairly hot to obtain maximum fuel economy plus minimal emissions. Thats why the radiator cap pressurises the cooling system to 1.35Kpa or 20 PSI which is pretty high.(higher pressure increases the boiling temperature) The temp gauge in Commodores is not really that accurate (the French would say it gives a suggestion of the temperature) so the true test of your engines temperature is whether it boils, and as you do not actually say it boils I'd suggest everything is normal and you do not have an issue!..

[Brett_jjj]

Geez hako,1 mark from hot! That doesnt leave much room on the gauge to monitor the engine temp on a hot day or up a long hill.Ever thought about changing the temp sender?It might be stuffed.

[Keggy]

Sensor and Sender
was one of the 1st things i changed

all the replacement parts are brand new

it doesn't boil...so thats a Plus i guess..
its not a dodgy gauge cos i hace changed clusters also

[Brett_jjj]

Was reading on here that someone bought and fitted a new sender and it made the temp gauge read hotter like 3/4 instead of around 1/4.They said they took it back and got another sender and the gauge was back to normal once this other sender was fitted.(the 2 senders were a bit different).Could be worth checking it out if you find nothing wrong with the cooling system.Most VS cooling fans cut in at around half way on the gauge.

[VS_Pete_1]

You may be worrying about nothing - if the temp drops once the fan kicks in and the temp drops that means your cooling system is OK....my VS which I've owned for about 7 years now, goes to 1 notch from HOT before the fan comes on and then the temp drops quickly down to about 1/2. Many other Commodores act the same and I really think it is not the engine overheating but just that Ecotec engines are designed to run fairly hot to obtain maximum fuel economy plus minimal emissions. Thats why the radiator cap pressurises the cooling system to 1.35Kpa or 20 PSI which is pretty high.(higher pressure increases the boiling temperature) The temp gauge in Commodores is not really that accurate (the French would say it gives a suggestion of the temperature) so the true test of your engines temperature is whether it boils, and as you do not actually say it boils I'd suggest everything is normal and you do not have an issue!..

Spot on as usual hako

[hako]

Geez hako,1 mark from hot! That doesnt leave much room on the gauge to monitor the engine temp on a hot day or up a long hill.Ever thought about changing the temp sender?It might be stuffed.

Why? - but I know where you are coming from. If the temp ever got above that mark I would immediately ease off or stop. I know that when the fans come on, the temp is about 104 to 109 deg C which is what the specifications say....and that my thermostat opens fully at 106 deg C, so above that point I'm in the danger zone.
I cannot see the point in spending hard earned cash just to make the temp gauge read slightly different but the same, if you get what I mean.
By the way, have you plugged your Tech1 in to see what temp your fan comes on at Lo and Hi?

[Brett_jjj]

Low fan comes on at around 105 or so, I cant remember exactly.I havent looked at the hi fan cut in temp.It rarely gets up that hot,unless sitting in traffic for ages,which doesnt happen much where I'm at.I will have to check it out.You could probably get another sender from a wreckers or from an old blown up engine for nothing.It would be interesting to see if it makes any difference trying other senders.Like the guy I mentioned before in the other post that changed his sender and it made his gauge read highter.He got another different one and it was "normal" again.Ive ran across a couple of VS's that run at 3/4 or so,but most Ive seen the fan kicks in at around half way on the gauge.Id be afraid I wouldnt notice it in time if mine ran that close to the hot mark.Do you know if the dash "beeps" similar to the low fuel/handbrake warnings when the engine overheats on the VS?

[The1]

The low speed fan comes on at 104c
or if the aircon has been turned on and the car is traveling less than 61km/h
or if coolant temp sensor has failed

The low speed fan turns of if
Aircon is not on or traveling more than 64km/h
or the temp goes under 99.5c

The high speed fan will only come on if the low speed fan has been operational for 2seconds and
BCM Fault
Coolant is above 109c
or if coolant temp sensor failed

The high speed fan will turn off if
coolant temp is less than 105c
A/C Pressure if less than 1370kpa or turned off

[The Big O]

Had the same problem exactly. Bought a new temperature guage sender at Repco and nope still sat at nearly H till the fans cut in then back to half. Got one from Holden and nope same problem. Not losing water and not boiling over just guage red at H if i sat at idle in traffic. If i flicked the A/C on which will force the thermo fans to cut in i could keep the guage at 1/2.
Then i red a post in this forum that said make sure the collar on the temp sender is white and not black. Had a look and i had black. Called Holden spares and they looked and had one with white collar left. Put it in and guage never gets above half.
Hasn't missed a beat since.

P.S - I also replaced all the normal things before reading this post so i wouldn't under estimate the simple things.

[BoNeZ-01]

Just to clarify, which sensor did you replace with a white collard sensor?
The coolant temp sensor for the computer, or the temp sender for dash gauge?
I also read about that, but it was for the coolant sensor.
This would tell the computer to kick the fan in sooner, because it was set at a lower lower temp than the black sensor, so temp gauge wouldn't get as high before the fan kicked in.

[executer]

go to an auto electrician and have it checked for electrolysis. Coulld be it. its not friendly for the car at all. Very common in vs v6's due to bad earthing. Happened to me, it destroyed the motor and the tranny. Thankfully i got wiped off by a truck so i could buy a new one.

[ORIXVywags]

You may be worrying about nothing - if the temp drops once the fan kicks in and the temp drops that means your cooling system is OK....my VS which I've owned for about 7 years now, goes to 1 notch from HOT before the fan comes on and then the temp drops quickly down to about 1/2. Many other Commodores act the same and I really think it is not the engine overheating but just that Ecotec engines are designed to run fairly hot to obtain maximum fuel economy plus minimal emissions. Thats why the radiator cap pressurises the cooling system to 1.35Kpa or 20 PSI which is pretty high.(higher pressure increases the boiling temperature) The temp gauge in Commodores is not really that accurate (the French would say it gives a suggestion of the temperature) so the true test of your engines temperature is whether it boils, and as you do not actually say it boils I'd suggest everything is normal and you do not have an issue!..

WOW, 1 notch from hot, that is insane, the worst I ever got was, middle of summer, towing a loaded trailer to Canberra from Sydney and got about 5/8 the way to hot, and I dont have a tranny cooler, (I know very stupid - no tranny cooler and towing = $$$)

[wortus]

With the temperature gauge and it's sender unit it would be a good idea to test each individually. The sender unit is probably a temperature dependent resistor hence the voltage at it's terminal will change when a constant current is applied. You can obtain the resistance readings for certain temperatures and check the sender with a thermometer and ohm meter. Same with the gauge connect it's wire to ground through certain resistance values. I got these valuse off an automotive instrument repair shop when I had a Torana. You can also tes the ECU sensor as well and I am sure some small circuit can be built up and connected in it's place to trigger the ECU to start the fans. This process will provide definative data to determine what if anything is at fault and that the system is correctly callibrated.

[ragrim]

i did not bother to read the entire replies but have you tried.. Bleeding the air from the system at the thermostat? from my experiance its the number one cause for a temp mis reading as the car is reading the air temp in the air lock rather than water temp.

Air lock can mean dash gauge is reading 120c while ECU is only reading 105c which is why the thermo is not kicking in.

Ive had the same problem in both VS's ive owned.