Mechanics

308 THUMPING NOISE

1977 Holden HX • V8 2WD Automatic • 250,000 miles

I have a blue 308 that if left to idle for a few minutes it starts to make a popping or cluncking noise from the thermostat i've just replaced the thermostat because of this noise but still have the same problem. Any ideas would be great
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Azzaand
July 12, 2011.




I would say it is boiling in the block, make sure that the thermostat is working and it is a quality unit with a bleed hole, cheap thermostats with out bleed holes can caused these problems.

Mhpautos
Jul 12, 2011.
Ok so i've put a new thermostat in with bleed hole. Still having the same problem not quite so bad but still making a noise like the thermostat is opening then slamming shut if that makes any sense.
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Tiny
Azzaand
Jul 15, 2011.
You may have air trapped in the heater system, take off a heater hose and allow coolant to flow from bothy directions, plug the hose with your finger and get coolant flowing out of the heater and visea versa.

Mhpautos
Jul 15, 2011.
Also ensure radiator is not part blockerd as well.

Mhpautos
Jul 15, 2011.
I disconected the heater hoses altogether as it's on gas i've tried bleeding it through the hoses that go to the converter. As far as I can tell the radiater is clear as I can run water through it from both ends. I'm at a loss as to what else it can be.

Thanks for taken the time to try help me out.

Tiny
Azzaand
Jul 15, 2011.
Radiator can still be part blocked, garden hose pressure will not dislodge muck that may be blocking core tubes, you may have over 1/2 the core tubes blocked and still have flow the way you tested, are the top and bottom hoses getting hot? Converter hoses hot and heater hoses both hot? Try running with out a thermostat and see if it still knocks.

Mhpautos
Jul 15, 2011.
Also With the thermostat out look at the flow in the radiator, just fill to above tubes and watch for strong flow with no thermostat, if not the water pump is faulty.

Mhpautos
Jul 15, 2011.
I've put a brand new pump in it just the other day I thought that was the original problem. How can I test the radiator cores the top and bottom hoses all feel the same temp.

Cheers
Aaron

Tiny
Azzaand
Jul 15, 2011.
The core will have to be flow tested by a radiator repairer.

Mhpautos
Jul 15, 2011.

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