VZ Overheating Mystery

[sssmechanicholdenbrisb]

yes in the five ten minute period will "fluctuate slightly" level rise drop sometimes a lot ! this is due to the expansion of the coolant and air locks being forced out
so to recap more simply

drain
fill
bleed
start
2000rpm till fans on
off
bleed
cap on while off
top up overflow

notes:
always top up if level drops MUST BE FULL THE WHOLE TIME if not full to cap top! as else will let air in
keep overflow hose into fill cap or block off

to bleed: engine stopped fill up open screw (a bit! not take off completely) located @ rhf top radiator vz
and keep topping up until only fluid comes out the screw close screw

Also during whole procedure:
set heater too hottest
fan speed two
on the windscreen only (top of dash only)
A/C OFF or fans always on

that is from the manuals guys all accesibbale info through haynes etc etc.

 

[Aussie_Dark]

Thanks again SSSMechanicHoldenBrisb...

Just another question. What does the bleed screw look like? Is it the black plug facing the back of the car at the top right hand side of the radiator as you face the front of the car?

 

[sssmechanicholdenbrisb]

hey mate sorry long day today did 23 cars im F**ed

the screw isa a Phillips head (unless aftermarket radiator) and yes is at top rh side facing the engine side very easy to get to just remove the cover's six or so clips and take cover off!!!! good luck and let us know how you go!~

 

[Aussie_Dark]

SSSMechanicHoldenBrisb

23 cars... that's amazing.

OK... I did what you suggested and I am pretty sure I did not get the expected results.

Observations:
1. A small amount of steam started to occur fairly quickly after starting the car (about 1 min).
2. As the time progressed the bubbling became more and more violent and coolant was spewing out of the fill port.
3. Ran the car for 11 minutes. Coolant continued to spew out of the fill port and the level never really dropped.
4. After 11 minutes I stopped the car and the coolant dissappeared from the fill port. I topped up the level and it took at least 2 litres.
5. The fans did not come on at any time.
6. The maximum reading on the temperature gauge throughout was just above 25%.

After pleading with a service manager of one of the larger dealerships in Adelaide, I am dropping the car off for special attention. It is sad that the previous two times resulted in a changed cap, then a tightening of a clamp, instead of doing a complete investigation on it like I had hoped, but I feel more confident now that it will get the attention that it needs. I'm thinking that based on your advice that we have positively identified the problem as the thermostat.

I'm going to get to talk to the mechanic direct, so if I tell them what I have done then do you think they will be equally convinced?

Thank you very much for taking the trouble for helping me. I will post the outcome after Monday.

(Now comes the challenge of driving it to the dealership, which is over an hour away.)

 

[sssmechanicholdenbrisb]

hey mate sorry to hear that happen!
the ":boiling" of coolant as you describe is normally caused by a completely sieazed closed theremostat and so instead of criculating the coolant from the lower radiator hose it just boils the coolant inside the engine so as the sensor for the fans never senses the thermostat open it just reads the HOT AIR around the sensor which is not high enough to signal the fans on

will need (likely) thermostat ALL new coolantand a bleed
when you get your cart back dont open the cap unless you have a problem with overheating still as norm,all they will bleed the sytem very well especially if you have spoken to the service manager, trust me if he is involved it will come back fixed!!!!!~~~

 

[impulsesv6]

check out the supercheap auto website and online store...

the gasket is $1.95
and the thermostat is $37... bout 1/2 the price of repco

the supercheap freight is a rip off... just the $1.95 gasket = $28 bucks freight

the gasket, thermostat and 6 ngk spark plugs = $48 freight. haha

 

[DeanoV6]

Water Boils at 100 degrees unless its under pressure which raises the boiling temp
VZ normal operating temp is between 95 and 105 Deg, Fans dont come on until 108 deg.
So if the cooling system on a VZ is not under pressure it will Boil at normal operating temp and the fans wont come on!
This makes a mockery of the Holden bleading procedure, "cap off - 2000rpm till fans come on" (It will boil before fans come on ) found that out!
While the temp gauge will normally sit at 25% it can be boiling at 30%

You can watch your Temp with an exact digital readout by going into service mode on your digital dash readout
Hold down MODE and SET buttons when you turn ignition on, and scroll through till you find coolant temp.

I have found the best way to bleed them is to fill up till it comes out of the bleed screw on the radiator and then tighten up bleed screw and continue filling untill full, top up overflow tank take for short drive and then
top up again when it has cooled a bit and check it for a few days in the morning until all ok. Dont think any magical holden procedure required here.

Cooling system will not draw coolant from overflow tank if it has a leak ( easier to suck in air than draw coolant back into radiator) but it will certainly push it into overflow if it boils.

Before you go replacing this and that on a wild goose chase, a simple cooling system pressure test will help lots.
You haven't posted anything that would make me suspect a thermostat.
2 changed caps and a tightening of a clamp is probably on the right course (looking for a leak) so make sure you have no leaks and then make sure is bleed properly.

On my car the main problem was a F**ked radiator cap, system was not under pressure so it boiled, Also had a small leak from waterpump and where the cast pipe from radiator fits into the block. Over time as the coolant
level got down and air got into system, the small problem got worse. Had me thinking head gskt? thermostat? until I found out VZ normal operating temp is between 95 and 105 Deg.
Also the main large fan was siezed, the bearing cage had collapsed and balls had gone in all directions. You could not turn it by hand.(don't think this had much to do with the problem as second fan was operating)
The second smaller fan I have not seen going since I fixed the main fan.

Water pump Aftermarket $110 Japanese made, It is Quality!
2 o-ring things for cast pipe $60!!!! Holden
Radiator cap $22 Holden (seen exactly same one at Supercheep $15)
VZ Fan setup from wreckers $160

For coolant all the Holden owner manual said is a coolant meeting General Motors GM 6277M spec, I used Caltex Extended Life Coolant which meets this spec.

I believe what i have posted is correct please post if you think its not. I am NOT a Holden Mechanic just a Truck Driver.

 

[Aussie_Dark]

Thanks DeanoV6... I have heard that the caps are a flaw. I replaced the cap twice just in case. The car is now with Holdens until it is fixed. It will be interesting what the route cause is. I feel pretty sure the thermostat is stuffed, but I also think that the thermostat may not have been the original problem. I'm hoping that it is just the thermostat and I can get on with worry free motoring. The last couple of months have been hell.

 

[Aussie_Dark]

Thank you to everyone who posted.

OK... so here's the verdict....

Congratulations to all that suggested head gasket. Apparently the original problem was the head gaskets, which eventually caused a thermostat failure.

Holden has quoted $4800 to do both heads and the thermostat. I have managed to talk that down to $3500 to $4000 depending on what has to be done to the heads. I'm not sure what to do as even at $3500, it is a lot of money.

Something that may be of interest is that the Holden people said that 2005 to 2006 VZs are prone to head gasket failure, and that they would be fitting a new and improved head gasket that Holden determined to be a fix to the problem. Isn't it great to know that they have identified a flaw in the design, but we have to wear it. They said that they are seeing more and more VZs coming in with head gasket problems.

 

[Aussie_Dark]

Just an update. The last couple of days I have been weighing up my options. I have been considering whether to have the car fixed, or use it as a trade in with its current condition. Interesting that the few dealers and appraisals I had, indicated that I would be better off getting the fix and then trading it in. I can't understand this considering any dealer taking it on could get it fixed wholesale. Luckily I had a contact who put me in touch with a firm who indicated that they could do the job for between $2500 and $3000 depending on the damage to the heads. I have now paid off Holdens for the diagnostics work and broken the car out from their service division. I'm a little disappointed that Holdens would price themselves out of the work. Not only did they miss out on doing this job, but I am now more likely to get all my servicing done with this other firm. I have to add that this other firm has great credentials doing work for a racing team and also subcontract work (machining heads) for Holdens themselves.