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VZ Thermostat Issues - Does It Sound Right?

jackcurrie

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Problem #2 with the VZ, three months into owning it.

Just wondering what you guys think about how this all sounds. Anyway, I have a rather small leak (which only appears when running at operating temp), it is coolant and drips off the steering rack area - originally I thought it was PS fluid but it isn't. The coolant is slightly oily, this may be due to it coming off all the running gear as it drips. Anyway, MIGHT be the thermostat housing leaking, as pressure test was fine, but as it only leaks from this area at operating temp, signs point to thermostat. I've had ZERO issues with my cars coolant temp, or the gauge (this leak has only been apparent for about a week now, and havent lost much fluid or been on any drives over around 30 minutes).

Anyway, mechanic said to me, he see's some stain up near the head of my engine, and is concerned it could possibly be my head on its way. Although my oil is clear, coolant seems clear internally (except for the drops which feel somewhat oily), and my car isn't running poorly other than it being a sluggish 6.

What does this sound like to you guys, would you be satisfied its a thermostat housing leak? Or does it sound like it could be the head?

The cars only for 130000km on it, and hasnt been thrashed, by myself anyway.
 

Hrd455

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Waterpump? Thermostat is at the back of the motor
 

jackcurrie

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The leak appears to be coming from around the back of the motor.
 

franklinfrog

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I don't know heaps about the alloytec, but if your oil and coolant are both clean then it would be pretty safe to eliminate head gasket I would think. A leak could easily pick up oil residue running down an engine block.

Can you get under the car and degrease to try and find where it is leaking from, I assume it's at the back since you said near steering rack? Edit: Yes you just posted that.

Few heater hoses around there, check them out. Some info here about thermostat and also hoses in second thread.

http://forums.justcommodores.com.au/vz-holden-commodore-2004-2006/210427-vz-thermostat-replacement.html

https://forums.justcommodores.com.au/threads/thermostat-location-3-6l-alloytec.159599
 

jackcurrie

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Yeah I looked up other threads, but didnt find any that didn't have some sort of gauge/overheating issue along with the thermostat. So got me wondering if I might be up **** creek with a gasket issue.

Just to clarify, the car had a heater hose fixed yesterday (as it was the only leak found on a pressure test), then was left under pressure for 30min to find any possible other leaks. None found, but when driving it, I found the puddle under my car and took it back today. So the leak is only happening when the car is running at operating temp, and any leaks that would be apparent when cold/off have been ruled out. Which is why he believes its the thermostat, but once it was up on the hoist and he had a look, he saw stains up near the head - and we both got a little concerned.

The drips are leaving stains on the road once they dry, which worries me - will coolant leave 'oil spots', or can I assume its because of the oil the coolants picking up on its way down? Or maybe, is the coolant picking up oil from the engine, etc. Im just concerned as I dont have the usual signs of a thermostat problem, and those stains on the head are concerning me. I'm hoping theyre old stains from a heater tap leak I had about 2 weeks ago.
 

Hrd455

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I would check both heater hoses again and probally all the coolant hoses
 

DavesCalais

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There's an o ring in the heater hose connectors under the right hand engine cover near the rear of the motor very common leak pull the cover off and you should see red coolant dried up the connectors presuming it has genuine coolant. Can't replace the o ring either :/

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jackcurrie

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I would check both heater hoses again and probally all the coolant hoses


My mechanic ASSURES me it isn't this. As stated, it was held under pressure for 30 minutes and looked over every 5 minutes. So when cold, and under pressure, its fine. So can't assume its a hose of any type.
 

DavesCalais

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And that's the actual right side of the car not looking from the front or it would be the left :D

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RiCeY

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The spout at the front of the engine that connects to your top radiator hose has 2 seals. These seals leak into the area below where the intake manifold bolts up and pools in the valley, When you drive it runs to the back of the motor and down from there.

Commonly misdiagnosed as thermostat when its simply 2 rubber seals that need replacing.

Pressure test doesnt show anything because the leak pools in that valley where you cant see it, then runs out when you drive.
 
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