Overheating problems
Hi guys, long time reader 1st time poster. Im having overheating problems with my hq. Ive got a stock 308, and it has been starting to play up a bit. When im driving around town its fine, say any speed under 80km. But as soon as I hit the freeway, the temperature just seems to instantly rise, and keeps going. Under 80km it sits on about 80 degrees, but on the freeway, within under 5 minutes it soars up to 100degrees and above. It seems to very temproarily drop temperature if i drop back to say 90km and speed back up to 100. that would drop the temperature by about 5 degrees, but would only stay that way for not even halve a minute. What do you think is the cause of the problem? Im thinking something to do with a blocked radiator and a broken water pump? Or is it something more sinister? The engine also seems to be making a sort of grinding noise when sitting on the freeway, it makes the noise for about 1/3 of a second, every 2 seconds if that makes any sence. Any help would be much appreciated. Thanks for your time
Over heating
How long since you have replaced the water pump? These engines will wear the pump and will also eat away the alloy timing cover behind the pump impeller. This results in cavitation resulting in your symptoms. Pull the pump off and check the timing cover. If it's worn away, will look like the inside of an aerobar, you can either replace the cover with a good second hand one (getting rare) new ones can be sourced from Holden but will have no fuel pump hole, as they are off efi models. or prepare the surface and braze it or a quick fix (can't guarentee longevity) may be to use something like knead it or similar. Someone may be able to recommend a better product. I know it may sound a bit bogey but could turn out to be a reliable fix. I haven't tried it so can't comment.
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Overheating
The symptoms sound a lot like a partially blocked radiator. At lower speeds there's less load on the engine but as the speed increases so does the load on the engine and the cooling system can't cope.
The water pump could be an issue too, if you replace it make sure you get one with a solid cast impeller not a crappy pressed one.
Cheers
David
aka hq308belmont
www.hq308.com
My Shed
Bottom Hose
THANKS
The Spring in the Bottom Radiator Hose is missing allowing the Hose to be sucked flat when the Power comes up.
The result is restricted Coolant Flow and overheating until you reduce the Power again.
T
Shed
Holdenpaedia, they're the brakes Mate.
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