ABY overheating

[Evilgoat76]

My S2 ABY is playing up
When the temp dropped a few weeks back I developed an overheating issue. Stopped driving her and took a lok discovering that somehow the bottom hoze had frozen solid. antifreeze levels all ok so a little confused. Gently defrosted her but the overheating persisted, after about 10 mins from cold gentle driving she starts to boil the coolant and the bottom hose stays cool.

So today bit the bullet and did the thermostat, all back in the right way, good clean, found a dodgey hose I need to replace and had a good clean up. Filled her up again, bled, topped up and let gently warm up on the drive, quick blast down the road and it promptly threw all the coolant out again

Bottom hose is now hot, fan is kicking in and out when it should, only thing I can think of is that its not bled right Does anyone have a bleed procedure for these and failing that any other ideas? I'm stuck right now as the bloody bleed screw in the rad has pulled the thread out of the rad. So need to source that before I can play anymore.

Ric

[Hammu]

Try to pressurize the cooling system and see if there is a leak somewhere.
Buy a new expansion tank cap, drill a hole to it, glue a bicycle tire valve to it or car tire valve, anything will do.
Apply small amount of pressure to cooling system and try to notice leaking air somewhere

My friend had just the same problem, overheated because of a small hole in aux radiator.
If there is a leak, cooling system can not make pressure so it will boil on 100c.
We removed the aux rad and plugged hoses, now it works like a boss.

[willg54]

there is a bleed procedure on here if you do a little search. shouldnt be too hard to find.

could be a sign of a blown head gasket if you're boiling up really quickly i think

[driftin jo]

How old is your rad ? It may well be blocked up from internal corrosion
try putting a garden hose in the top and see if it flows through properly with the bottom hose off.

[Evilgoat76]

Well looks like I have more to do Re-soldered the bleed screw, in doinf it I dropped it into the under tray, so in we go through the front grille with a magnet. Noticed a steady drip down there, not a lot of water, but enough. So rads now out and the only word I can use is rotten. Its leaking from thr seam where the bottom hose is attached so new rad needed. Just to add insult its been leaking a while and thats the cause of my dead aircon as the codensor is shot too and only had one bolt holding it on.

Water pump seems to be intact although I cant feel vanes I can feel the rotor and its attached to the pulley still. Cant spin it and turns with the engine (bar on crank pulley)

Water I put in to test earlier is still the same colour, no contaminants and head gasket was done 2K ago so I'm reluctant to beleive that.

Will take the opertunity to have a damn good clean up down there.

[Error404]

Sounds pretty average for a crappy Nissens rad. Do yourself a favour and get a Behr Hella or an AKG one.

p/n for the Behr rad is 8MK 376 711 281. Have a read of this thread first.

[Error404]

Or try an AKG rad, they make a lot of the rads on new Audis now and Hella outsource to them.

p/n 0085.491.0000

[madpugger]

If your coolant had frozen, I'd suspect the impellers on the water pump have sheered off and thats why it boils after 10 mins, due to no circulation.

[QuattroFever]

What antifreeze did you use? When was it last changed?

[Evilgoat76]

G12 and was topped up/checked before the freeze. I'm guessing that the overheating somehow got missed as she quite often does weeks of no more than a mile or so and the thermostat was jammed closed meaning the bottom hose didnt get mixed. I'm at a loss as to any other explaination. The first time she played up was the first real run for a good few weeks and certainly since the freeze.

Trying to decide wether to do pump (and with it cambelt) and all the other niggles while I'm at it. May as well get a condensor and belt and see about the AC too.