VX Overheating at High Speeds.

[VN SII]

So I've had my VX a little under a month now and I'm starting to get serious issues with the heating. Driving around town and in traffic is fine, but as soon as I try and drive 80-100KMPH it starts to spike into the the High Temp readings. And if I don't put the Heater on to flush out all the heat it'll Flash hot and hit the top of the dial. Coolant and Water was replaced when I bought the Car a month beforehand. Now even with the heater on it Flashes hot and hit the Red indicator, the only way I can get it to go down is to turn the Fans off and back on and it'll flush the heat for another 5-10 Mins, then go back to overheating.

BUT it still stays fine around town and in traffic. I replaced the coolant, which had no discolouration and now whenever I stop even in town the Coolant bottle is bubbling and heating up really badly. Ran the Error Code test and it's come up with "Satisfactory System". The only thing I could think of is the MAF sensor failing as that doesn't always read on the ECU. Any help would be amazing, don't want to blow a Head and still need to get to work ><.
Gonna retry the Error Codes tomorrow, check the Fans/Thermo, fuses new Drain the Radiator see if it's got any gunk in it and replace the coolant yet again.

Any suggestions? Specially as to why it would only overheat when going at high speeds/on the highway when the most air is getting to the Radiator?

 

[tml678]

I'll bet anything it's the thermostat mate, If it's stuffed it won't open as the coolant warms up which will trap the heat in the engine. simple, cheap fix

 

[VN SII]

Added more coolant and water just now, the Water in the radiator.
Put in enough coolant for it to come up to the neck but it just leaked out the bottom somewhere, that's not meant to happen is it? Couldn't see where it was leaking from my guess is it's just under the neck but above the bottom as I couldn't see or feel a crack.
The radiator water seems to be fairly dirty now, the same rusty colour my VN had when the Thermo went.
Gonna pop into Supercheap tomorrow to grab a new one, hope that's all it is.

Any chance I'd of cracked a head already? And what's the easiest way to check? I heard leaving the radiator cap off and revving the engine and checking for bubbles being caused in the radiator from the exhaust is an easy/good way?

Hoping it's just the Thermostat, thanks tml678. Getting to sleep tonight should be easy now knowing it could be something other than a cracked head >< haha.

 

[umair]

It can be a plugged radiator. To check simply take the top and bottom hose off the radiator. Note: Take the top hose off the engine side. Then take a garden hose and put it in the top hose in the radiator. Now check flow. The water you put in should come down the radiator at the same speed you put in. If it is coming down slowly then radiator is plugged.

 

[VN SII]

Definitely liking that idea Umair, wouldn't of thought to check like that >< Haha.

 

[Roota355]

From what you are saying the thermostat is likely your problem but dont rule out your radiator. Even if running the hose through the radiator seems ok the radiator tubes can baloon to the point where air cannot pass through the radiator properly causing overheating at speed. Best to pull that out too while the coolant is drained

 

[LordEthan2]

From what you are saying the thermostat is likely your problem but dont rule out your radiator. Even if running the hose through the radiator seems ok the radiator tubes can baloon to the point where air cannot pass through the radiator properly causing overheating at speed. Best to pull that out too while the coolant is drained

Mate, check that heater tap aswell.. see if its all sealed up and hasnt busted on you - isnt brittle etc.

 

[VN SII]

A mate just came round to give it a look, there was that much air in the Radiator/Hoses it wasn't funny and even after running it in idle you could hear some bubbling coming from the Engine, so I can only assume I've cracked the Passengers side head. Or the Thermo is effed and it's just the leftover coolant/water in their bubbling.
Only got a spare VN and VS Engine and I doubt the VS Heads are the same ><. Anyone know how much a VX one would cost? (Head)
Gonna drop it into Ultra Tune tomorrow as it's the best mechanics in town and see if they can find out if it's the head or the Heater-tap etc. .

 

[umair]

Did you just buy the car?

 

[VN SII]

On the 18th of last month, from a Dealership. Drove nearly 1000K's back home so I doubt any warranty's would still be good.