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The mkiv Supra Owners Club

Fluctuating temp gauge ....


bens747

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Driving back home today and noticed the temp gauge right up in the heavens and then it dropped down. Then up and down. It seemed to do this on the change of the throttle. Got back home and there was plenty of water but the expansion tank was bubbling like a kettle. Could it be a sticky thermostat??. Any help would be appreciated.

Edited by bens747 (see edit history)
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Surely a failing water pump would be sign that it was leaking. What else can fail on a water pump. Thanks :)

 

The impeller blades can erode causing erratic flow, or depending on construction the impeller can become loose and ether not turn or also turn erratically, it doesn't necessarily have to leak.

You mentioned the temp seemed to change with the RPM;)

Edited by Tricky-Ricky (see edit history)
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The impeller blades can erode causing erratic flow, or depending on construction the impeller can become loose and ether not turn or also turn erratically, it doesn't necessarily have to leak.

You mentioned the temp seemed to change with the RPM;)

 

Yeps tricky it did appear to do that and now you mention it would sound like a water pump would cause that if not what else could it be ... am worried now lol

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I went through this years ago, being sensible, I cleaned the coolant system out, flushed it to death, changed the water pump (cr@p job) and it still wouldn't work.

 

Turned out, it was the rad, internally it had failed. If I ran the engine, warmed it up and then stopped it you could reach through from the fan and feel cold spots all over it (well more like most of it). Changed the rad and bingo all was ok again. The waterpump wheels are pretty tough. I'd suspect the rad first and the thermostat 2nd.

 

Change the rad cap and rad for NEW toyota OEM parts.

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Thanks mate will start to check it tomorrow. Foned Camberly Autofactors today just to get an idea on price of a water pump ... approx about 70-80 quid so not bad if it's that. but will go for the simple stuff first ... Thanks for your help will keep u posted ... :)

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Thanks mate will start to check it tomorrow. Foned Camberly Autofactors today just to get an idea on price of a water pump ... approx about 70-80 quid so not bad if it's that. but will go for the simple stuff first ... Thanks for your help will keep u posted ... :)

 

Water pump is a lot of labour on top - the front (of the engine) needs to come off...DIY job IMO unless you like giving money away. But like I say I don't think it's the issue.

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Water pump is a lot of labour on top - the front (of the engine) needs to come off...DIY job IMO unless you like giving money away. But like I say I don't think it's the issue.

 

Already did the core plugs behind the water pump and had the front of the engine off and did myself so no problem there. Will check the oil to see if it might be a head gasket. Hoping for just and airlock as my heater hasn't really worked properly since I did the last job on the core plugs .... :)

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Seems there was an airlock in the heater matrix which had cleared on a long run reducing the amount of water in the system. Which then started to overheat and overflow the expansion tank. Must have put 2.5 ltrs back in to the system.

 

Thanks to Ian C for the advice on how to clear air locks in the cooling system and now everything seems to be working ok. Will keep an eye on it just to to be sure everything is deffo ok and working properly :)

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