Bleeding cooling system

NinjaA2

Member
Anyone had any experience bleeding coolent system on a audi a2 1.6fsi

Running car with cap off and get up to temp but water and coolent just bubbles out the bottle is there a bleed screw or? And bottom pipe of rad always feels cold

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Anyone help with this? Is there bleed screws on the 1.6fsi or case just leaving it with cap off cause the fan hasn't started at all

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I'll start by outlining the 'official' procedure which uses a suction pump system with 3 way valve to first draw air from the engine via a special cap on the expansion tank.
With a negative pressure in the engine, the valve is then turned to allow coolant to be drawn into the engine from a container of pre mixed anti freeze.
The 'vacuum' process is repeated to obtain the max static fill and the system removed.
The engine is then run at 1500 rpm for 2 min and the expansion tank topped up while the engine is still running.
Stop engine and fit filler cap.
Start engine and run at idle until both main radiator hoses are warm.

There are no separate bleed valves so it appears the system is self venting and will eventually purge any trapped air via the small return line on the expansion tank.
The FSI system runs at a very high temp so it will take ages for the thermostat to open (long after the gauge shows 90 deg) so coolant starts to flow round the radiator and get rid of the remaining air.

Cheers Spike
 
Thanxs spike so it's a special job then rather than running the engine with cap off

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Thanxs spike so it's a special job then rather than running the engine with cap off

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Spike was indicating the official procedure, the option of running the car up to heat with the cap off is known to also work in most cases and has been used many times with success.

Steve B
 
Yh I have tried just seems the expansion tank overflows and just smokes alot, I did at one point have hot air coming our vents but they went cold again, the bottom rad pipe always feels cold us it worth putting cap in and going for drive see if it holds

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But temp stays at 90 and never see the rad fan run

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It may be that the water temperature is at 90 where the temperature gauge sender is, but cold where the fan sender unit is (two very different locations.

Have you tested the fan yet to see if a direct 12v spins it?

You need to eliminate individual potential causes one by one, first the fan motor then a potential blockage in the radiator (checking the fan first is easier than determining of there is a blockage).

Steve B
 
Yh can I run the fan using vag com or is it easier to test using 12v to the 2 wire on fan fan?
It did use to run at a reduced speed but the ac stopped working and I have fault code from that sensor at front,
The system shouldn't be blocked as I have only changed the pipe at back and thermostat housing,

I get worries cause it does start to bubble over even tho the temp gauge shows 90, but once u turn engine off it sucks the water untill it's gone

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I think the FSi electronic thermostat only fully opens around 110 or 115C so without the pressure cap on the coolant may start to boil. The 'official' procedure specifies the cap is fitted for the final part of the fill process so I'd do that.

Q how much coolant has the system taken so far

Cheers Spike
 
But I have lost some from the expansion tank when I bubbles up and spills out

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Right I have run car with cap on for couple days now and temp gauge sits at 90 and the bottle is sitting around max mark, feels like running ok,

The cabin gets hot air and cold air when turned down on climate control, but rad fan still dosent do anything?

This means my system is bled and all is ok or should I keep eye on it as still not seen or heard rad fan run

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Hi Spike - sorry to post direct to you - but forgot how to post a Thread !
Audi A2 Coolant Pressurised Problems
Hi same old story
2001 1.4tdi 106,000 miles full Mot unmarked bodywork
Coolant system pressurised - even after 3 days non use - does not de pressurise at all - fitted new blue cap on coolant bottle - release and Whoosh !
Top radiator hose always hard - gets hot but radiator and bottom hose always cold
Both Heater matrix pipes get hot - no heat in cabin
Webasto diesel heater fires up ( spray pipe freeze on sensor in front of radiator ! ) no heat in cabin
Have bled webasto - a little Air
Have bled radiator top hose - Air for 3 seconds
Gauge gets to 90 degrees - do over 60mph and rises - drop to under 60 mph -
back to 90 degrees
Could it be
Water pump - how to test
Thermostat
Heater matrix - garage flushed this and coolant system said not blocked ( car the same as before it went in !)
Cylinder head ???? - if It is this do not mind spending say £500
£100 skim head
£100 cylinder gasket kit
£200 local labour Newcastle
£100 other
ANYONE KNOW REPUTABLE HEAD SPECIALIST IN NEWCASTLE AREA ?
But will this solve problem - 2001 1.4tdi 106,000 miles full Mot unmarked bodywork no other problems - owned since May 2003 on 18000 miles
Would not like to sell like it is
Scrap ?
Part exchange ?
Actually runs okay if not pushed hard
How long after gauge reaches 90 degrees should heater start to work
Bet this is a common problem !!!
May just use for up to 20 mile trips in future !
Sniff test at local garage next
Cambelt and water pump changed 26,000 miles ago at Audi - had to force them to change pump - charged me but not convinced they did this - got car home and needed 2 litres pf G12 - WILL NEVER GO TO AUDI AGAIN
Any feedback appreciated
 
Hi
Thanks for info - but can you tell me how to post a question ?
Kind Regards

If you have read the FAQ it should become obvious.
Select Forum from the menu bar
Select a Forum to start a new thread in (such as General)
click on the + Post New Thread button (you may need the right permissions to do this).
Type a subject heading and the body of your text.
Click the Submit new thread in the bottom right of the screen

That should have you sorted.

Apologies for the thread hijack
 
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