1.8T AUM - Temp Gauge Reads 110c, Pump ok, Rad Hot, Blowers in car hot? Please Help....

[darthtrainer]

:1zhelp:Hi there all, Ive not posted in a while but i regularly read this forum and others and am always impressed at the community spirit which im hoping will help me out a bit here and I hope you can help me with some advice. I Changed my thermostat at the weekend on my 1.8T (AUM) as the temp gauge was doing a dance whilst the car was warming up to 90c, very entertaining but ultimately needed fixing. After checking the posts on the best forum in the world!! (This One) i opted to change the thermostat; and now the temp rises evenly and reasonably quickly to just below 90c. Now my issue if any of you experts can advise me is its going higher, up to 110c+? the blowers for the car heat are fine, its nice and hot in the car and appears to run fine; also the fans on the radiator do not seem to be kicking in when the dash reads 110c ? (what temp do they kick in at by the way and do they run off a different coolant sensor?)

Ive noticed turning the engine off and leaving seems to bring it back to 90c for while but eventually it starts to creep up again to 110c? Today i noticed that the temp while driving normally (no higher than say 3000rpm at any point) to work builds up to 110c then if i put my foot down the temp decreases to 90c? idle at lights again starts to fall? Im thinking Sensor but im open to thoughts if you can spare any?

Can anyone confirm that its likely to be my dash temp sensor, coolant issue or something simple and not a major engine blow up issue? many thanks in advance and i promise to give something to charity if you can help me :1zhelp:

[Aptuning]

I take it the thermostat you got was original oem quality? if it was, then try changing the COOLANT TEMP SENSOR which is located on the right hand side of the engine itself. It'll most likey be a 4pin green top sensor. Trade parts specialists charge £28+vat or get one from ebay for £8 from a VW parts shop.

[darthtrainer]

Hi thanks for the reply. Yes ive replaced the thermostat with a decent OEM one, ive also since replaced the temp sensor which seems to have sorted it and im only left with the original intermittent rough idle problem; which after cleaning my throttle body seems a lot better but still there. Like a vibration through the car when its sat at lights and idling, sometimes its there, sometimes its gone. When i cleaned the throttle body there was a small amount of oil in it. Any thoughts?

[Aptuning]

Hard to say really. if you have access to diagnostics then see if that brings up anything.
Going back to basics though, I would check the spark plugs, coil packs, disconnecting the MAF and see if it runs BETTER unplugged! Usually if a MAF is going/gone then when you unplug it, the ecu will revert to stock settings and so the car will idle normally.
Check for any air leaks ANYWHERE! Honestly there is so much to look for. Do yourself a little favour though and get some silicone vac pipe and start changing all the old pipes.
Hope this helps a little

[Crasher]

How do you now the pump is OK, that is a classic case of spinning pump impeller.