VT - Overheats randomly, Temp Spikes and Drops Quickly After Turning Heater On

[ashtonwright]

Hi Team,

Just recently my commodore has started to play up with the temperature.

When driving around town the temperature randomly spikes,dashboard beeps at me and then it goes down quickly after turning the heater on for a minute.

The radiator is full of coolant and the fans do come on. The coolant has stayed at the same level... so there isn't a leak. I lift the bonnet the engine feels regular temperature, no steam or anything.

Could it be the radiator cap? I had a look and looks ok..... but not too sure how to know if it's in bad condition.

Could it be a Computer Fault with the BCM? If so is this difficult and expensive to fix?

Could it be air in the system?

ALSO... do you think there will be any risk to the engine if I continue to drive with it happening?

Thanks in advance and hope to hear from one of you commodore experts soon!!

Cheers

Ash

 

[dirty hands]

no to ecu / bcm /computer etc
no to rad cap
thermostat working ok ?
maybe a faulty temp sender near thermo housing / a faulty wire

what happens after you turn the heater off again .. after the beeping temp warning heater on for a minute etc
how old are the hoses of the cooling system ..are they soft when hot

could that heater valve be faulty
cant think of anything else
unless its the manifold gasket

 

[ashtonwright]

Thanks for your reply 'Dirty Hands', great to get a second opinion.

Perhaps it is the temp sender, I had quick look and seemed ok, but I guess without taking it out and swapping it I won't know a?

Normally just give the heater a quick blast to get it down, and car seems to run absolutely fine....until the next random occurance.

Ill check the hoses next time it says it's hot, will hard or soft be a good?

Hmmm heater valve? whats that?? whats it used for? Typically I have my temp on cold regardless of a/c or not, and after the temp spike turning it to hot always seems to drop it nice and fast... Like a 5 sec drop back to normal.

What do you think would be wrong with the gasket? how would it affect the temp??

Anyway, thanks again for your advice Dirty, any other help would be greatly appreciated.

Cheers

Ash

 

[dirty hands]

we have the same model car

something is wrong but what
by opening the heater system you are taking away the heat or pressure off the main cooling system
dropping the temp again

wonder if the water pump is old
blocked radiator ?
is air con on all the time when this happens

hot -hoses hard is good soft means they can collapse restricting coolant flow through system

manifold gaskets... leak slow.... a common problem

heater valve .... in the engine bay ... this pic is from another member

 

[iChris]

Is your thermostat functioning as it should? No air in the system?

 

[mpower]

Kind of sounds like air in the system to me.

 

[ashtonwright]

we have the same model car

something is wrong but what
by opening the heater system you are taking away the heat or pressure off the main cooling system
dropping the temp again

wonder if the water pump is old
blocked radiator ?
is air con on all the time when this happens

hot -hoses hard is good soft means they can collapse restricting coolant flow through system

manifold gaskets... leak slow.... a common problem

heater valve .... in the engine bay ... this pic is from another member

Thanks Dirty, I'll check my hoses. So I'm looking for C? Also how do you think the heater valve would effect the temp??

If it was you what would be your go to options to solve it? Heater Valve, then Temper Sender then Thermostat?

 

[ashtonwright]

Thanks for your reply 'iChris' and 'mpower',

Just curious, what makes you think its the thermo over the other suggestions made by dirty in post number 2 or 4?

Im not sure how to check the thermostat?? Do you have any suggestions? Would air in the system make the thermostat function abnormally do you think??

If you have a method for getting the air out I'd much appreciate it.

 

[dirty hands]

C is the larger exploded view of engine bay heater valve .... its an engineering thing dont worry about it

several other posts/threads in the forum about bleeding the air out of the cooling system

some one may tell you before I can find it

air in the system can be fixed and you should be right to go

 

[ashtonwright]

Thanks mate, much appreciated... I'll go on the hunt.

If anyone else spots it, if you could direct me it'd be great