Frothing Coolant Bottle

[JoeeS3]

As the title says, my coolant bottle is frothing...very very slowly.

Last night when i turned my engine off i decided to check for froth or anything like that again, so slowly took my coolant cap off and as i was doing that, coolant seemed to have forced it self out the side of the coolant bottle. the stopped when pressure was relieved. I will *** that the other day i added a little bit of radweld as i had a small leak coming from the back of the engine somewhere. I am not loosing coolant anymore but i am getting some frothing.

No mayo stuff on oil cap and dipstick looks good.

Could anyone shed some light on the problem could it be air getting into the coolant bottle? from the small leak where it forced itself out? head gasket?

I may possibly change the coolant bottle and see if that makes any changes.

 

[ruffrida]

Not sure but could be an air block in the system somewhere causing it to boil back to the header tank, used to have a punto which was a nightmare for this, as soon as it got to temp would try and boil its self by spitting coolant out the tank. Flushing the system was easy on that as the was a bleed nipple on the rad, think it is the same with 8L

 

[GOLF-MK3-GTI]

Change the O-Ring on the cap. Had an issue like this on a golf gti before.

 

[JoeeS3]

Change the O-Ring on the cap. Had an issue like this on a golf gti before.

well i took the cap off and left it running and the froth was ever so slowly increasing, so i dont think it would be related to the o ring on the cap

 

[ruffrida]

Sounds like an air lock even more now, ya need to bleed the system, either a screw on the rad or on a coolant pipe quite high up on the engine, only deal inoil burners, so sorry cant help ya find it!

Not sure if this will help - DIY: Complete Coolant System Flush (the easy way)

 

[ruffrida]

This maybe better - http://www.audi-sport.net/vb/a3-s3-forum-8l-chassis/169171-s3-coolant-bleed-urgent.html