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D3 - Engine Bay Everything under the bonnet

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Old 1st August 2018, 07:59 PM
Rick Rick is offline
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Default Coolant airlock help on s8

Where are the bleed valves for our s8's?
I had a hose off to do the manifold a while back, topped back up after the work but today a little 20 mile trip saw the gauge hitting nearly red.
Im not losing any water from anywhere and no steam so seems to be an airlock me thinks. The res pot is at max but when car warms it rises to the top of the filler neck.
Help appreciated.
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Old 2nd August 2018, 07:22 AM
Rick Rick is offline
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Today I went to sart the car and just with ignition on the temp gauge is sitting on 90. Dont remember this happening before.
Dodgy thermostat possibly?
When i do a run later i will try and get some real time info with vcds and see whats going on.
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Old 2nd August 2018, 08:40 AM
mannyo mannyo is offline
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could just be a sensor, especially if the gauge said 90 and the engine was cold. but better be safe than sorry. I am not sure on the location of the coolant temp sensor on the V10.
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Old 2nd August 2018, 09:12 AM
HPsauce HPsauce is offline
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Is it the same "standard" green sensor used widely on VAG cars?
If it is then remember it's a 4-pin connector because there are 2 separate sensors inside.

On D2s and the like one sensor mainly feeds the temperature gauge while the other informs the ECUs, so you can see some rather weird effects when there's a partial failure.
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Old 2nd August 2018, 01:28 PM
Rick Rick is offline
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This morning was 90 at 05:30 then when i went for a run at 12:30 it was reading 127 on a dead cold engine and showing throttle body temp as 42 when the ambient was 24.5. The throttle body i will concede as had the bonnet up and sun baking down on it but the 127 is a joke. This was on vcds i was getting these readings.
I have no water leaking whatsoever the levels do not drop. The cap doesnt even his and spit when i open it.
So possibly the temp sender unit?
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Old 2nd August 2018, 07:02 PM
Rick Rick is offline
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Was about 4mm of water in the plug/socket causing it to do the needle dance. All dried off. Just had a little spin and hovering around the 90 mark as it used to. Pain in the arse to get to though!
Still i like free fixes that only take an hour or so.

It is a 2 pin unit on the S8. Im going to replace it anyway just to be sure. Its still sitting at 90 on a dead cold lump. Cant risk it not work and the fan not kicking in.
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Last edited by Rick; 4th August 2018 at 08:15 AM.
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