What temperature?

[axistr]

True, Axistr, the cap will lift boiling point too. The reason I say 100 is too hot, you can run a tractor at full load all day in the summer, with a capillary tube temp gauge, if the cooling system is correct, it will not go over about 92. 100 is way too hot. There is a problem either with your remote gauge or the cooling system.

I agree and the HQ-HZ were designed to run between 85-95 with a 82 thermostat. Its interesting that when the VN commodores were introduced they used a 92-94 thermostat and the computer didn't trigger the low speed electric fan till 102 degrees. The thermostat opening temperatures gradually increased after the HZ trying to reduce emissions. I don't agree with the temps that the later cars run at but its uncommon to see cars broken down on the hwy and overheating these days.

[b-rock-05]

Hi all and happy new year, does anyone have an opinion on waterless coolants,and if this would help these problems ?

[wbute]

Did 308’s in general have an overheating problem? I have heard a few people say they did.

[Valencia]

Did 308’s in general have an overheating problem? I have heard a few people say they did.

All cars overheat if the coolant system isnt up to scratch
Never had a problem with over heating 308s had a few in my time

[davegmh]

Kiwivan, firstly I’m no mechanic but when I had my 308 sandy it would always run hot and the gauge would go to the maximum on a hot day. I have a mate who is an absolute Holden freak and he told me that everything Holden puts on paper about their cars is correct except the right thermostat for a 308. On his advice I put in a 160 deg thermostat and from that sec on it ran as cool as a cucumber. Just my experience, hope it helps.

[Innuendo]

Hi all and happy new year, does anyone have an opinion on waterless coolants,and if this would help these problems ?

Waterless coolants have a higher boiling point and would help. The main reasons for overheating basically come down to: Blockage, Malfunctioning/Incorrect Parts, Cavitation and Air Flow.
Cavitation is air in the system as a result of not being bled properly (fill point or bleed hole should always be at the highest point of the cooling system). An impeller rotating too fast can be detrimental. I.E a incorrect water pump pulley.

Things to check:
Thermostat opening at correct temperature.
Thermostat is not installed upside down.
Water disappearing under higher revs with radiator cap off. (Hold revs and fill, replace cap)
Hot spots in radiator core - blockage.
Open heater taps when filling radiator and bleeding system.
Water in engine oil? Blown head gasket, cracked head.
Leaks.
Steam out exhaust pipe - Blown head gasket, cracked head, manifold corrosion, crack or gasket seal fail.

A radiator cowling (like a thermo/engine fan) only work at lower speeds I.E in traffic. Open road air speed will surpass cowl and fans.

[wbute]

I only ask because I know of some locals who bought a HZ sedan with a 308 and factory air, they could never get to run cool enough and in the end sold it. That was from new. I have heard other people say it wasn’t unusual for similar problems.
To me it would be fixed by putting a radiator with more rows in it. But WB they did completely update the radiator and all the V8’s had a full shroud. To me that says Holden recognised there was a limit on the HQ to HZ radiator efficiency.
Just a thought.

[axistr]

Just a few facts to think about,

WB & commodores all went to cross flow radiator design because the tubes weren't long enough in the conventional top & bottom tank radiators, and the coolant didn't stay in the tubes long enough to get cooled when the engine was under load. With car design changing to even lower aerodynamic front end designs the only way was across (crossflow design) to lengthen the coolant passing time in tube to cool. I have found that five core radiators didn't do much for cooling either. Three core radiators are usually more efficient. By the time the 4th&5th tubes get air flow from the previous tubes the air is so hot it makes them inefficient. The other problem is its harder for the air to travel through very thick cores and for that reason they are more restrictive and clog fins more easily. Most car radiators are either single or 2 row aluminium radiators these days. Aluminium radiators transfer heat much better but generally don't have as long service life.

My preferred radiator is the old brass copper units, 2 or 3 row well made core with lots of fins per inch between the tubes. When ever I get presented with an overheating vehicle the first things I check is the fan and shroud operation, restricted or blocked outer fins, heat gun test, coolant condition and level, pressure test, gas test for carbon monoxide in the cooling system. These check only take around 10 minutes. If no obvious things are found with these basic checks. and tests, I remove the radiator and send it out for the local radiator company to service the radiator. This service must include removing the top and bottom tanks and visually check and clean out every tube. I have been caught out a few times over the years when so call good radiator company's flush and paint them black. You put the radiator back in and have the same problem and you naturally think it can't be the radiator, and you can easily spend lots of time and money chasing the problem and all along its as simple as blocked radiator internal core tubes. I generally recommend radiator servicing every five years for regular used vehicles. Many coolant in the past have caused tubes to block up and crystalize in the tubes.

I hope the above helps you to make a better informed approach to cooling system overheating diagnosis.

P.S always insure the gauges are accurate in the car before jumping to a conclusion.

Lenny.

[Kiwivan]

Is my 15lb cap correct for the recovery system,
As I changed from the non recovery cap?
Have done the thermostat and have a water pump coming in the next couple of days and will keep you updated.
Will do the radiator clean out when I do the water pump

Cheers Kiwivan

[axistr]

15lb cap will be fine, the difference between recovery and non recovery is the recovery caps have a one way valve/flap and top seal so when the engine cools down it allows the coolant to be sucked back into the cooling system. Any leak around the cap will allow air to be sucked in and not coolant from the overflow bottle. When the system pressure exceeds more the 15lbs the cap pressure spring allows coolant to vent to the overflow bottle. If the system is working properly the radiator should be 100% full at all times.