Sarge's A2 Servicing Information

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FSi (Engine code: BAD) Overheating, Steam coming out of expansion tank (globe)

The FSi suffers from a few known issues but it is a great engine when running properly (I currently now own 3 A2 FSi's) and you have to know what to look for, or what to do when things start to go wrong.

Here I'm going to discuss the overheating/coolant loss issue with damage to the expansion tank and/or steam coming out the expansion tank. This obviously means, there is overheating, the main cause of this, I have found is the Electronic thermostat aka the map controlled engine cooling thermostat F265. When this fails the very high temperatures arise, I have seen have these temperatures gone up to 125 degrees! (there is no warning lights on dash nor any DTC's logged that VCDS picks up). This effectively 'cooks' everything in the cooling system and the plastics (and sometimes the seals) are prone to damaging. If you're having these issues, once cool, remove the cap from the expansion tank, have a good look around inside it and you may see floating bits of plastic or 'cracks' inside in the expansion tank, you can put your finger in and try to push the plastic and see if it moves or cracks away, time to replace it if there is any signs of damage. These bits of plastic can then circulate around the cooling system and teeny bits stick to everything.

In the pictures attached you can see the expansion tank cracked away inside it and bits floating in the cooling circuit. The electronic thermostat removed has these orangey (coolant colour) coloured bits stuck to it, so I would strongly advise a complete flush of the old coolant out of the system in this case.

I would advise removal of both temp sensors (Green and Grey), check/clean/replace as a precaution.

Note: This problem needs to be addressed immediately, if it isn't dealt with it can be a very serious and cause issues like warping/cracking of the head and blown head gasket as well as other damage, you'll no doubt be aware that these days this sort of damage can easily write off the car due to the costs involved.



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