A3 8V No Heat Diagnosis

[Sid2020]

If your not getting high engine temps and the system is getting hot I would think your pump is working

[cliffcoggin]

Chris.

If you manage to get the heater unblocked, or if you have to replace it, consider what caused it to become blocked initially. It's possible there is a burst bag of silica gel that will give you another blockage.

See this for an explanation of a problem that I only recently became aware of:

https://www.youtube.com/watch?v=39ngHGvMzEg

 

[Chris777]

Hi Cliff

Thanks for your input

I came across the burst /leaking silica bag suggestion. Only some 8V got them apparently and if was present says on side of header tank. Thankfully looks like mine never had one. It is a copart rebuild front damage, the coolant temp sensor had somehow dislodged and all coolant out when I got it. Not sure if impact somehow dislodged but can find no other leak or damage to why the coolant came out. I have read the matrix can gum up if left sitting without coolant for a while (money was maybe 6 weeks max) hoping it's just a flush. Looking at the coolant carefully that came out couple tiny bits of plastic in it so also slight concern where from and if more stuck anywhere

[Sid2020]

Finding out what VAG cars got the bag is  almost impossible, I’ve never came across any service document that states what vin numbers they were introduced from which also means we don’t know what vehicles were affected. The logic behind the bags makes sense from a VAG  standpoint, they have to allow for all regions of the world  where maybe service procedures are not followed so a few blocked heater matrix’s is better then engines failing  due to corroded engine internals. A pain in the !Removed! but still better then skimming engine heads and blocks

[Chris777]

Hi Matt.

It says 'Mit Silikat' on side of header tank if has one apparently. Mine doesn't have this so presuming it didn't have in first place.

[Sid2020]

Unfortunately it wasnt printed on every reservoir that it was fitted in but this may be year dependent. Shining a torch thru the empty reservoir bottle while looking inside is a good way of checking for one also if in doubt. 
below photo is from a T6 with nothing on bottle as a idea where to look 

[Chris777]

What am I looking at in the pic sorry?

 

[Sid2020]

8 minutes ago, Chris777 said:

What am I looking at in the pic sorry?

 

Thats a bag circled. That’s where the bags are sometimes found on bottles without mit silikat printed on them 

[Chris777]

Got you, I've had a good look and can't see one or the remnants of one

[Chris777]

Hi guys

When flushing out should I run up to let thermostat open before taking bottom pipe off?

Just thinking to try and get as much out as poss but then If I do and then cool when I vacuum refill will that mean more poss places for air blocks again?

[Sid2020]

7 minutes ago, Chris777 said:

Hi guys

When flushing out should I run up to let thermostat open before taking bottom pipe off?

Just thinking to try and get as much out as poss but then If I do and then cool when I vacuum refill will that mean more poss places for air blocks again?

Won’t do any harm

[Sid2020]

Just now, Sid2020 said:

Won’t do any harm

A vacuum refill should fill both sides of the thermostat with possibly a small bit of trapped air but nothing major 

[Chris777]

Thanks Matt

[Chris777]

Afternoon 

Hope had nice weekend. Mine has been fighting the !Removed! coolant lines off the water pump as getting to the ports of the matrix next to the fire wall with that !Removed! heat shield is a reet ****. Decided to disconnect as next join as didn't want snap the matrix port as you warned . Finally got off pump. The lower pipe was full of lovely fresh coolant but the top looked gunked up and crusty. Pic below. Is the top one the inlet to the matrix or the other way round? Does all this muck look like matrix block / bad maintenance or likely lead to having to replace pump?

Got too cold so had to abandon but all ready to now try and flush. Just wanted get your thoughts so far 

[Stevey Y]

14 minutes ago, Chris777 said:

Afternoon 

Hope had nice weekend. Mine has been fighting the !Removed! coolant lines off the water pump as getting to the ports of the matrix next to the fire wall with that !Removed! heat shield is a reet ****. Decided to disconnect as next join as didn't want snap the matrix port as you warned . Finally got off pump. The lower pipe was full of lovely fresh coolant but the top looked gunked up and crusty. Pic below. Is the top one the inlet to the matrix or the other way round? Does all this muck look like matrix block / bad maintenance or likely lead to having to replace pump?

Got too cold so had to abandon but all ready to now try and flush. Just wanted get your thoughts so far 

Hi are you positive that is the pump?, it looks like a thermostat housing with the two bypass ports, [smaller bore pipes], the main pump is run by the cam belt, but the gunge definitely looks normal as most people dont bother to change the antifreeze at regular intervals or just top it up with tap water which is full of calcium.

Steve.

[Chris777]

 hi mate

Thanks for reply, no not certain at all am a complete newbie at this. I though the water pump and start housing all came as one? Those 2 pipes I've taken off that lead to the matrix do they go onto the bypass ports then sorry? Am I OK using these to flush / backflush the matrix as can get off from port right up against the fire wall.

thanks for your help

[Sid2020]

I believe what I’m seeing is the combined water pump and thermostat but hard to tell from the picture. The crud could also be from a additive that someone has added to seal a leak

[Sid2020]

These are from a A1 1.4 tfsi that I did a few weeks ago so if any of it looks familiar then this is what you may also have 

[Chris777]

Hiya Matt

Thanks for your message and pics. That is similar, same side and placement. Right side of the engine block then leading to the matrix. Just looks a little different on the A1. I have had those pipes off and the 2 off the rad and give a good flush through with the garden hose on full. I wanted to also use the karcher on half power but couldn't find a nozzle to fit just the hardest power lance and can only have that full power so didn't try it incase ruptured the matrix. I flowed and back flowed the matrix and seemed OK flow. I was hoping to see a load of crud come out like see on some YouTube vids but from what could see just little bit of coolant then water. It wasn't pouring through but seemed constant both ways. Hooked back up and run the Wynns flush through then flushed clean water again and dumped all out again. When was running up with the flush still no heat so wondering if done absolutely nothing with all the flushing.

All left is to redo the coolant tomorrow with the vacuum pump which I didn't do initially just a normal top up fill. So hoping that it was an air block but was also hoping when run up after flush with just water would at least get a little heat to give me hope.

The pump does that suck rather than push into the matrix? Do you have a flow diagram for the system by chance?

Worth taking any other pipes off etc to run through before connecting all back up?

[Sid2020]

46 minutes ago, Chris777 said:

Hiya Matt

Thanks for your message and pics. That is similar, same side and placement. Right side of the engine block then leading to the matrix. Just looks a little different on the A1. I have had those pipes off and the 2 off the rad and give a good flush through with the garden hose on full. I wanted to also use the karcher on half power but couldn't find a nozzle to fit just the hardest power lance and can only have that full power so didn't try it incase ruptured the matrix. I flowed and back flowed the matrix and seemed OK flow. I was hoping to see a load of crud come out like see on some YouTube vids but from what could see just little bit of coolant then water. It wasn't pouring through but seemed constant both ways. Hooked back up and run the Wynns flush through then flushed clean water again and dumped all out again. When was running up with the flush still no heat so wondering if done absolutely nothing with all the flushing.

All left is to redo the coolant tomorrow with the vacuum pump which I didn't do initially just a normal top up fill. So hoping that it was an air block but was also hoping when run up after flush with just water would at least get a little heat to give me hope.

The pump does that suck rather than push into the matrix? Do you have a flow diagram for the system by chance?

Worth taking any other pipes off etc to run through before connecting all back up?

I don’t have access to the Audi coolant schematics but typically the water pump circulates coolant around the engine block, turbo if water cooled, egr cooler and any other heat critical parts and the matrix for occupant comfort. Only once the coolant reaches a certain temperature does the thermostat open and allow coolant to flow from the pump into the radiator for cooling. To remove air fully the system must be upto temperature so the thermostat opens and allows the flow around the complete coolant system and allow trapped air to be pushed back to the reservoir 

[Sid2020]

This picture was taken from the b9 forum and if your a3 has similar design it would allow coolant to flow in and out of the matrix but if the water ways are blocked you would get no heat transfer into the cabin as it needs to travel thru the water ways for that to happen 

[Chris777]

Seemed to have OK flow, I put the hose on both outlets and flowed both ways. Was expecting to see some gunk but seemed quite clear. Could the water pump fail just insufficient flow? Damaged impeller or something but throw no check engine, no error, no leakage etc? When I very first let the remaining coolant out after it had its little bump noticed 2 tiny bits of hard plastic wondering if could be the impeller but would that throw check engine?

[Sid2020]

57 minutes ago, Chris777 said:

Seemed to have OK flow, I put the hose on both outlets and flowed both ways. Was expecting to see some gunk but seemed quite clear. Could the water pump fail just insufficient flow? Damaged impeller or something but throw no check engine, no error, no leakage etc? When I very first let the remaining coolant out after it had its little bump noticed 2 tiny bits of hard plastic wondering if could be the impeller but would that throw check engine?

Anything is possible with these cars. If the pump had failed I would expect to see some faults as you would get localized over heating of certain parts of the engine. Are the pipes to the bulkhead getting hot even when your getting no hot air in the cabin

[Chris777]

Hi Matt

Thanks for your message. The pipes into the matrix seem to be getting warm the top one I think it is warmer than the bottom. The bottom rad hose that I take off to drain noticed hardly gets warm even though the pipe at top of rad above it is red hot. The pipe feel cool of not cold and the coolant temp sensor is on that corner and reads 90degree on the cluster? (This sensor was out when I got the car and looked like where coolant had leaked from after accident)

I used one vacuum for the 1st time today but was only a cheap one and couldn't work out how to get the little air in the line to the bottle out when it starts the intake. Seemed to only take about 5 litres again. Run it up and the heaters worked for first time but only when I was revving to 2k ish if on idle went back cold and the puffing/clicking sound started again. On 2k revs it was warmish but not hot and soon as dropped my foot off Instantly cooled air 

[Sid2020]

1 hour ago, Chris777 said:

Hi Matt

Thanks for your message. The pipes into the matrix seem to be getting warm the top one I think it is warmer than the bottom. The bottom rad hose that I take off to drain noticed hardly gets warm even though the pipe at top of rad above it is red hot. The pipe feel cool of not cold and the coolant temp sensor is on that corner and reads 90degree on the cluster? (This sensor was out when I got the car and looked like where coolant had leaked from after accident)

I used one vacuum for the 1st time today but was only a cheap one and couldn't work out how to get the little air in the line to the bottle out when it starts the intake. Seemed to only take about 5 litres again. Run it up and the heaters worked for first time but only when I was revving to 2k ish if on idle went back cold and the puffing/clicking sound started again. On 2k revs it was warmish but not hot and soon as dropped my foot off Instantly cooled air 

If the lower hose is from the thermostat then that might point to your issue. The matrix is usualy the last place that air remands trapped so if the thermostat is not opening fully and allowing full flow thru the system then it might not be able to push the air out. Have a look at your pump housing as you might be able to just remove the thermostat and test it in the kitchen with the kettle. Historicly If the thermostat fails open then usually you get lower running temperatures but fails shut you get over heating  but with modern diesels over heating tends not to be such a problem as due to there efficiency they don’t generate lots of excess heat hence why newer cars have active air flaps to stop air flow thru the radiator when not needed.