Renewing coolant, haynes manual instruction necessary?

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Northstar
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Renewing coolant, haynes manual instruction necessary?

Post by Northstar »

On refilling, it tells me to remove the temperature sensor to expel air.
Can i get away with not doing this step or is it necessary?
RUM4MO
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Re: Renewing coolant, haynes manual instruction necessary?

Post by RUM4MO »

Strange that you mention this, when my wife had a 2002 Polo 9N with the 1.4 16V 75PS petrol engine, I always got the cam belt replaced every 4 years and that included a exchange water pump, auxiliary belt and VW G12+ etc coolant concentrate, so I never ever had opened up the cooling system myself.

Move forward a few years and I was looking after my older daughter's late 2009 Ibiza 1.4 16V 85PS SC and it also had its cambelt replaced at 5 year intervals again using genuine VW Group parts including exchange water pump auxiliary belt and G12++ etc coolant concentrate - then a couple of years later I started to notice the odd engine coolant temperature sensor "duff" signal fault code, so I replaced the sensor, O-ring seal and retainer clip with genuine VW Group parts and topped up with a 50% G12++ coolant mix, then noticed that I could not get rid of trapped air, heater would heat up and go cold - and it looked like it would never would purge the air out. So, after checking on the internet, I found that VW Group suggest that you always remove that sensor and fill up an empty system until bubble free coolant comes out that opening, then while continuing to filling up the coolant system, refit that sensor - result being normal heater performance.

Sorry long story, but I'm giving you my experiences and yes they do reflect what you have read - I would think that this only applies to certain engine types as I've never ever needed to do that in the past with older cars.
Northstar
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Re: Renewing coolant, haynes manual instruction necessary?

Post by Northstar »

Ah right, i take it you partly drained the the coolant, but replaced the sensor before starting to refill to purge the air. Oh right, will take it off then. Thanks for the reply
RUM4MO
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Re: Renewing coolant, haynes manual instruction necessary?

Post by RUM4MO »

Essentially yes!

Actually, the plan was to have the new sensor ready with its new O-ring seal, or at least ready beside where I was working, I removed the sensor retaining clip, it slides out, then eased the sensor out, but could not be sure that the O-ring seal had also come out or was still in the opening, so that is why I ended up losing more coolant than planned.

One bit of advise I would give, if you have never removed these black plastic retainer clips before, maybe buy a new one and a new O-ring seal, as the last thing that you need is ending up with a coolant leak because you have lost the O-ring seal or worse the black retainer clip, maybe the O-ring seal sits below the sensor and not around its body, I've forgotten.
Northstar
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Re: Renewing coolant, haynes manual instruction necessary?

Post by Northstar »

Hi again, yes i got the clip and o ring. Just hope they sre the right ones (gulp)
Being cowardly, (lol) i have tried teasing the clip on the car to see how tight it's pushed in and seemed to move easy enough.

Ive also got the phone number of a tow truck guy ust incase lol

Does the sensor pull out easy once retaing clip is removed?
Northstar
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Re: Renewing coolant, haynes manual instruction necessary?

Post by Northstar »

Forgot say got clip n oring from local vw dealership
RUM4MO
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Re: Renewing coolant, haynes manual instruction necessary?

Post by RUM4MO »

Sorry for missing your latest posting, yes the sensor should come out easily, especially as you don't need to remove the connector, I had trouble once with a V6 Passat engine as its sensor was right at the rear top of the engine, but a bit low down, as the engine was cold, I think that the cooling system was slightly below atmospheric pressure so that and the location made getting that one out a bit less easy, your one is more accessible so should not cause any issues.

The clip, I think I've taken out maybe using a big screwdriver, though grabbing it with grips/pliers should also work fine - it is an easy and simple system.
Northstar
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Re: Renewing coolant, haynes manual instruction necessary?

Post by Northstar »

Thanks for your help mate, will be getting round to it when i grt dome time off work
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