VS Commodore boiling over for no apparent reason...

[electraglide]

Hi guys,

VS Commodore has brand new radiator, cap, thermo, water pump but has recently started to boil over through the overflow tank run-off hose.
This only happens once the car and engine are shut off and the heat soaks in.

When driving and stopped in traffic the fan is kicking in at around 2/3 and brings the guage back down to 1/2. Seems fine.

Could it be the new thermo is dodgy?

[accentstencil]

Was the cooling system bled after the new parts were installed?

[electraglide]

It would have been bled, but not sure how well...

[sjmcc]

When mine did this it was just a matter of the pressure seal on the cap being faulty. This mean't the pressure wasn't held properly in the system making the coolant boil at a lower temperature.

[sleepa]

My guess is an air bubble, I had a car that did exactly that 7 years ago, I wish I could remember what was wrong with it. I believe that when the engine is running the coolant flows through continually, but stops when the engine stops, so it's obviously getting too hot for some reason.

Bleed the system again, just to be sure.

[electraglide]

Thanks guys, I will try to bleed again and see if this sorts it.

[hako]

I agree with sjmcc - sounds like the radiator cap is not holding pressure - under $10 to replace.

[bandit10]

what make cap did you get? the cheapo ones from supercrap dont work to well, the original ones are the best are they CPC or something like that

[sjmcc]

I agree with sjmcc - sounds like the radiator cap is not holding pressure - under $10 to replace.

From personal experience with this I find CPC caps are quite good and as you say usually around 7-12 bucks at autobarn, repco, supercheap etc etc

[electraglide]

The cap is brand new, came with the brand new rad.

Over the weekend I bled the system thoroughly which seems to have done the trick.

Since then I have had my alternator shit itself... reco alt now fitted.

Now onto some less urgent issues: the fuel consumption is absolutely shithouse. Time to replace the O2 sensors??

[slayer208]

Check the camshaft sensor, dude!. I've read up that once the cam sensor goes the EFI box will run in a more direct injection mode and use much more fuel. My VS-II averages well above 10KPL+ but that is driving sensibly with not doing anything stupid. And she's also due for its service.

regards!

[slayer208]

Forgot to answer your question,
Yeah, your new thermostat could be dodgey. I'd go for a high flow one. Might help you out a little. Also, worst case scenario is that you've got a cracked head or a blown headgasket.

[electraglide]

Update: I am getting error code 23 which could be the cause of the poor fuel economy.

Anyone know what the most common cause of error 23 is?

[94VRtuff]

Hi I have a vr but a code 23 is mat sensor circuit high voltage, hth cheers Bob.

[electraglide]

Is it most likely that the sensor is stuffed? If so, where can I buy a replacement sensor (outside of Holden dealers...)

[Brett_jjj]

When it comes to sensors you are better off buying genuine parts from holden.Ive run into a few problems caused by different sensors that were "cheap".Especially the CAS.(Crank Angle Sensor).Just something to think about though.In the long run it can save you money, dramas and stuffing around buying genuine.

[sleepa]

Sometimes the Holden dealer is cheaper for parts, I suggest getting prices from places like Bursons, Repco and compare it to the genuine Holden part, if they are around the same price then just go genuine.

[hsv91ss]

How much are the sensors worth normally? I am only getting approx 280 a tank

[electraglide]

So the general consensus is that my sensor is stuffed, thus causing the code 23 error, and that I should replace the sensor with a genuine one?

[Brett_jjj]

Clear the error code 23 by disconnecting the car battery for a minute or two. Reconnect the battery,then confirm the error has been cleared by doing a diagnostic check.If its gone,then go for a drive for about 15 -20 minutes and then re check to see if the error has returned.If it returns and there is nothing wrong with the wiring or connector going to the sensor,then Id replce the sensor with a genuine one.If it doesnt come back,then it was probably just a one off fault which can happen sometimes.Cheers.

[electraglide]

Thanks Brett_jjj I will try that and see how I go.

Would be great to improve the economy somewhat though... probably should give her a service!

[Brett_jjj]

A complete service is the go if it hasnt been done for ages and you are chasing economy.Change the engine oil and oil filter,the air filter,the fuel filter,the auto trans filter(if its auto).Change the plugs and leads as well.A bottle of injector cleaner through the fuel tank and also give the throttle body and its passages a clean with some carby and throttle body cleaner.This will help with the fuel economy.Old ignition coils can effect the fuel economy too.I also noticed a big difference when I fitted 3 new genuine holden ignition coils to my V6.The 3 ignition coils must slowly loose their performance over time which gradually effects the fuel economy.My VS gets around 6-8 litres per 100km on the highway,and around 10-12 km per 100km around town.I dont drive it slowly either.I also only use 98 octane fuel.

[electraglide]

Great advice... lucky its a long weekend!

[electraglide]

Completed the service today and found the Air Temperature Sensor was unplugged so that explains the error code 23. Hopefully now this is plugged safely in again, my fuel economy will improve somewhat.

[electraglide]

Hey guys, the original reason for this thread seems to have been solved by a $10 CPC radiator cap to replace my new and expensive one which came with the new rad.