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VY over heating then not

adalimbi

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Hi Guys, My VY V6 Commodore overheated on the way home tonight, needle went as far as it could go and the gauge and I had the little alarm bell going off at me. Never have had an issue with it before but it is about to hit 440,000kms. I pulled over with hazards on, threw the heat on full blast and accidentally hit the AC button. Temp dropped super fast back to normal. I was close to home so drove on and a few kms up the road temp rose up to 3/4 then dropped straight back down again to 1/3 and stayed there for the last km or 2 home. So before I sink money into it that I literary don't have, what are the chances of being the pump? I will check Thermo fan relay, coolant level, and Bleed system in the morning.
 

87VLCALAIS

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I went through this a about 5 years. Slightly lower k's than you. The overheating usually occurred after acceleration/higher RPM than normal, though not always.

I could drive for weeks on end without an issue then it would overheat. Turning the heater to high and running the heater fan would bring the temperature down.

I bought a new water pump thinking there might be worn/corroded impellers. When I took it off the pump was in excellent condition. I also flushed the system. The problem persisted. One odd thing was that if you stopped the engine and then restarted the car the temperature would return to normal immediately but if you continued to drive without stopping the engine the temperature would remain high.

In the end I replaced the radiator and the problem went away. After I replaced the radiator I came to the conclusion there was debris sitting at the bottom of the side tank. At higher RPM I think this was getting stirred up and with the water flow sucked against the tubes of the radiator core blocking the water flow, causing the over heating. When you stopped the engine, the water flow that was holding the debris over the tubes stopped and the debris fell back to the bottom of the side tank. When I flushed the the system I had left the radiator in the car and I presume the debris remained in the bottom of the side tank. I should have removed the radiator to flush it properly.

I'd try a radiator flush and then if that didn't work I consider a new radiator. I've also seen pictures of the impellors being completely eroded so that cannot be discounted either.

Definitely check the water level. It might be the thermostat though that's normally only a problem where it doesn't open during warm up. If the car warmed up and the temperature was stable beforehand I doubt it's will be the thermostat. I don't think it will be the fan, unless you're doing a lot of stop start driving and/or the ambient temperatures are pretty high. I find the fan rarely runs unless the aircon is on and even then I doubt the temps would rise that much if the fan failed to operate.
 
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Outbak

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Sounds like a new radiator is required.

I have 2003 VY Wagon I purchased new. I did lots of things such as had water pump change and system flushed. I had a new radiator put in and it fixed the problem. It's not a huge cost to replace.
 

Pollushon

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Get it pressure tested. That should isolate the issue. There's a few fail points that can cause similar behaviours. Rad, inlet gaskets, heater tap or heater core. Sometimes just the rad cap
 
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