Burping Query?

[DJ8226]

Evening Guys - I bled the cooling system on the S today after repairing a broken fuel pump wire which I must of caught whilst sanding / painting chassis, anyway wire repaired I proceded to bleed the cooling system. I did it as per the text book, fill swirl, heater to middle, run engine watch air come out, use bleed screw on radiator, squeeze bottom hose. All seemed fine bit of overflow as it got warm then it settled down so switched off re-fitted cap (non pressure one lets no go there)and went for a test drive.

1) All well on 8 mile test drive temp gauge spot on, no steam, no hot water smell.

2) Got home lifted the bonnet area around top of swirl is dry no seapage, no leaking hoses (as fitted kit yesterday

Cracked it me thinks!

Then after about a minute on tickover on the drive some overflow from the swirl didn't go out again but left it to cool down then removed cap and the tank is about half full and below the large swirl outlet that leads to the water pump.

Questions?

1) Is this normal and it is simply finding its own level as I know that some swirls DO NOT need to to be brimmed for the car to run without overheating.

2) Have I missed something?

3) Any recommendations and advice apprciated?

Also need to add that plastic tank is about half full and has not overflowed it has remained constant.


TIA - Damon

Edited by DJ8226 on Tuesday 4th May 22:16

[Griffinr]

It usually takes a couple of runs to get all the air out but as the engine cools it should suck water out of the plastic header into the swirl pot (assuming you have the pressure cap on the swirl pot) the cap has to be a good seal on the top of the swirl pot though to hold enough vacuum to suck the water back. The correct cap has a rubber seal under the top but some people use a standard cap with some rubber bonded on.

Rob.

[DJ8226]

Sorry for clarity its a 2.9 S3

[Gerald-TVR]

Hi Damon

Can of worms time!!!

Which way round do you have the caps? I have found that the non pressure relief cap, ie just a simple seal, goes best on swirl pot and pressure cap on expansion tank.

I agree it might take a few heat up/cool down cycles to expell all the air from the system.

I had found previously that when I fitted a new pressure cap on the swirl pot it did not allow the fuid to be sucked back into the pot on cooldown leaving the pot level about 1/3 down. So if it continues then try the non pressure cap on the swirl pot and the pressure cap on the expansion tank, it might solve your problem!

:waitstobeshotdowninflames:

Norman

[DJ8226]

Thanks Norman - I know this is a well trodden path. Non pressure is on the swirl at the moment. May try it the other way and see what happens. Irony is even if I cure it I will have to bleed it again as I want to flush the system again to get it as clean as I can as it was quite brown and murky when I first drained it. Will keep you posted.

Edited by DJ8226 on Wednesday 5th May 12:12

[DJ8226]

Evening Guys - update on the bleeding of the cooling system. Started her up tonight topped up the swirl ever so slightly warmed it up got a lttle bit of air out the radiator valve and a small bit of overflow from the swirl once it got warm. Fan kicked in and cooled it down so went for a drive. Came back temp gauge spot on I let it run again on the drive until the fan kicked in again all well NO LEAKS & NO OVERFLOW so looks like I have cracked it. Well pleased. For info non pressure cap remains on the swirl and pressure cap is on the header. Need to do it all again thought to flush out the rusty water, but given its not been changed for some time I think this is normal.

Just one more question for now - Once it cooled down the swirl is just over half full is this acceptable?

Edited by DJ8226 on Thursday 6th May 21:00

[Gerald-TVR]

On mine the level only drops down to the bottom of the filler neck!!!

[Rower]

You sound as if you are sorted now , but one process has not ben mentioned in this thread ( I think ) is making sure that the heater matrix is charged ie heater on .

Without wanting to rake up the swirl-pot expansion bottle debate yet again ! I have always added an extra rubber gasket to the swirl pot cap , cut from an old inner tube it makes the seal complete , I and the previous owner of this car have never had a problem ,I have a few of thse seals already cut , if anyone wants one email thro my profile and I will send one.

Rower.