Too Cold.

[himself26]

First off Thank you to anyone who reads this & tries to help.


Problem is the Heaters don’t work. The car is a 2002 S3 8L


I’ve flushed the coolant system both ways with the thermostat removed. Then flushed the heater matrix the same.

Result is a good steady flow of clean water through the engine / radiator & heater matrix.

I then reassembled including fitting a new thermostat & new coolant flange (gearbox side of cylinder head)

I have a good continuous flow coming back to the header tank & can’t find any obvious water leaks. The car gets up to running temp in around 5mins temperature gauge sits perfect at 90degree’s car never over heats it starts / runs & idles pretty much spot-on.

However as soon as it’s up to running temp the radiator top pipe (RHS when looking from front of car) is solid. As if there’s a proper air lock.

I also can’t get any sustained heat from the heater. Once the car’s at operating temperature I can turn heaters on but I only get warm air for around 5 / 10 seconds then the blow stone cold.

I’ve done the heater module test on VCDS & no faults reported. This is now doing my head in as it’s like driving a fast fridge in this weather.


Any help in sorting this would be much appreciated.

 

[Stuart B]

Have you tried running with the cap off the expansion tank for a little while?

When you say the car runs 'pretty much spot on? Does it misfire don't a few seconds when you first start it?

 

[himself26]

Have you tried running with the cap off the expansion tank for a little while?

When you say the car runs 'pretty much spot on? Does it misfire don't a few seconds when you first start it?

There's no misfire on start up Stuart & yeah I've run it for around 15 / 20mins with expansion tank cap off to make sure system is properly bled. However soon as the cap is put back on the pipe pressurises quite quickly ?

 

[himself26]

Really Odd thing is not one of the other water pipes I've checked under the bonnet are pressurising ? It really has me baffled.
More to the point I'm really hoping to rule out the Head Gasket as I assume that's what you where thinking when you asked about misfire on start-up Stuart B ?

 

[Stuart B]

I've only had coolant pipes behaving like that when the head gasket is broken between piston and coolant. But that usually is followed by a misfire the next morning because the pressurised coolant returns to the sit on top of the cylinder, but the coolant level also drops. So maybe it's a blockage still

I also had put some head repair fluid in it and didn't run the engine on high heat long enough so it reduced the heater matrix and even though the car reached temperature i only got luke warm air.

When I changed my head gasket I am not sure it was broken, as they are two steel plates pressed together and don't easily break.

 

[<tuffty/>]

Have you bled the radiator from the lower drain tap? quite often have to do this on cars that have had the coolant drained down

Normally start from cold, expansion bottle cap off then wait until its up to enough temp for the stat to open, drain some coolant from the tap being mindful of coolant levels... rinse repeat a couple of times to be sure... that generally clears most airlocks from coolant drain...

I'd advise fitting a bit of pipe over the taps outlet to prevent you from getting coolant on you while operating the tap

<tuffty/>

 

[himself26]

Have you bled the radiator from the lower drain tap? quite often have to do this on cars that have had the coolant drained down

Normally start from cold, expansion bottle cap off then wait until its up to enough temp for the stat to open, drain some coolant from the tap being mindful of coolant levels... rinse repeat a couple of times to be sure... that generally clears most airlocks from coolant drain...

I'd advise fitting a bit of pipe over the taps outlet to prevent you from getting coolant on you while operating the tap

<tuffty/>

Thanks for this Tuffty. I will give it a try. As upto now I've only run water through the pipes ive had off.

 

[himself26]

I've only had coolant pipes behaving like that when the head gasket is broken between piston and coolant. But that usually is followed by a misfire the next morning because the pressurised coolant returns to the sit on top of the cylinder, but the coolant level also drops. So maybe it's a blockage still


View attachment 171839


I also had put some head repair fluid in it and didn't run the engine on high heat long enough so it reduced the heater matrix and even though the car reached temperature i only got luke warm air.

When I changed my head gasket I am not sure it was broken, as they are two steel plates pressed together and don't easily break.

I am having to top up with water every 3 or 4 days I'm praying its not the head gasket but it is what I was thinking. However I don't understand why I'm not getting any warm air through the heaters even if the gasket is gone ?

 

[himself26]

If ????? it is the head gasket. Are any of these head gasket sealer liquids any good just to get me through the winter. As once the cold weathers gone i'll pull the engine out & do a re-build.

Must admit I was thinking this so been looking at "Hyper-Seal Gold" does anyone have any experience with this or any other head gasket sealing compounds ?

 

[Stuart B]

You can get a sniff test to look for gases in the water, I used that stuff head sealant in my s3 to sort out my issue, I also used the radweld heavy duty stuff on my TT to stop a leak from my after run pipe.

These heads can also crack.

It's your water pump working?

 

[himself26]

Did the leak seal work Stuart ?

 

[Stuart B]

It stopped losing coolant, its the £30 a bottle yellow stuff isn't it? I used it to see if S3 was okay for 6 months and my downpipe broke so I changed the head gasket at the same time. But these head gaskets are made of stern stuff like I said steel plates they are not like cardboard fiat punto head gaskets that rip and crack.

This repair stuff is frowned upon on forums. Are you sure the water pump is working also what about the after run pump could the high pressure be causing fluid leaking from there?

Some people simply put RadWeld in every year into old cars just to keep them water tight, I put 2 cans of tyre weld into my Mazda 3 front wheel because it was leaked slowly for three last 3 years and has now stopped leaking.

 

[himself26]

cheers I bought some Pro tech 545 to try. if it gets me through the winter it will do m8. Thanks for the help