Weird heating on my car...

[shark_90]

I had mega heating problems with mine last winter and changing the thermostat solved the problem for me. Work that out!

[Error404]

Ahh well I'm confused even more now...

I do have a brand new matrix though
Have you tried back flushing ?

Also, worth trying flushing the system with some TSP powder which will clear out LOADS of skanky stuff, the matrix is pretty fine it must block up easily

[johne]

I think there's a few myths here. Here's my understanding:

Water flows through the heater matrix regardless of the thermostat position. In fact the matrix is the bypass to relieve pressure on the water pump when the thermostat is closed for most 5 cylinder blocks except turbo engines that have the auxilary water pump as well.

The setting of the temperature control on the heater has no affect on the flow of water flowing through the heater matrix because there is no water valve inside the heater

The water pump has been sized to cope with the wide RPM range our cars are capable of to ensure it doesn't cavitate at high RPM. As a consequence it's output at low speeds, i.e. idle is very low. (Some might say too low, which may be why it was changed for the RS2) Couple that with a bit of blocking up of the heater matrix with old age and you can get no heat at idle.................. You'll also notice that heat output rises as the RPM rises. That's normal, it's linked to the pump capacity.

Efficient working of the heater is linked to a properly working thermostat. It's the closing temperature of the thermostat that sets your operating temperature under normal conditions and it's this temperature that tends to drop with old age. If you see way under 87 degrees cruising on the motorway it's time for a new one.

I agree with @mcandmar and don't turn up the heater until the engine is warm but in fact if you've got a good thermostat, warm air is available within a few yards of setting off. The 3B/ABY is a big block and takes a while to warm up. An old thermostat or one with a bleed hole in it will only make this worse.

John

[denniselbows]

note to every one don't put in a gsf thermostat in your s2 as it has a bleed hole in it and indeed it make things a lot worse. it has totaly ****et mine up and looks like i am having to replace it again with a proper one

[Error404]

even OEM ones are ****** in my experience
I've replaced mine twice in the last year, and even the ones that "work" can't maintain a consistant temperature... i think that is common on the 7A though TBH. Maybe the same retard who designed the MFTS had a hand in specing the thermostat

[johne]

note to every one don't put in a gsf thermostat in your s2 as it has a bleed hole in it and indeed it make things a lot worse. it has totaly ****et mine up and looks like i am having to replace it again with a proper one

I did post this on another thread. It's the Flusser brand. Avoid like the proverbial plague...........

John

[s2driveruk]

even OEM ones are ****** in my experience
I've replaced mine twice in the last year, and even the ones that "work" can't maintain a consistant temperature... i think that is common on the 7A though TBH. Maybe the same retard who designed the MFTS had a hand in specing the thermostat

agreed....i think he was in on the coupe boot drainage too

[johne]

even OEM ones are ****** in my experience
I've replaced mine twice in the last year, and even the ones that "work" can't maintain a consistant temperature... i think that is common on the 7A though TBH. Maybe the same retard who designed the MFTS had a hand in specing the thermostat

I ended up testing 4 thermostats all together to find out which was the best - which included my OEM one originally fitted to the car from new.

I know you'll all laugh but the best one was a QH one, 88 degrees, but at least I'm nice and warm.................

John

[S2central.net]

I think there's a few myths here. Here's my understanding:

Water flows through the heater matrix regardless of the thermostat position. In fact the matrix is the bypass to relieve pressure on the water pump when the thermostat is closed for most 5 cylinder blocks except turbo engines that have the auxilary water pump as well.

The setting of the temperature control on the heater has no affect on the flow of water flowing through the heater matrix because there is no water valve inside the heater

The water pump has been sized to cope with the wide RPM range our cars are capable of to ensure it doesn't cavitate at high RPM. As a consequence it's output at low speeds, i.e. idle is very low. (Some might say too low, which may be why it was changed for the RS2) Couple that with a bit of blocking up of the heater matrix with old age and you can get no heat at idle.................. You'll also notice that heat output rises as the RPM rises. That's normal, it's linked to the pump capacity.

Efficient working of the heater is linked to a properly working thermostat. It's the closing temperature of the thermostat that sets your operating temperature under normal conditions and it's this temperature that tends to drop with old age. If you see way under 87 degrees cruising on the motorway it's time for a new one.

I agree with @mcandmar and don't turn up the heater until the engine is warm but in fact if you've got a good thermostat, warm air is available within a few yards of setting off. The 3B/ABY is a big block and takes a while to warm up. An old thermostat or one with a bleed hole in it will only make this worse.

John

Nice info John..... Thanks for that.

I renewed my thermostat maybe 2-3 yrs ago with an OEM one from VAGparts. It's still working OK, but your explanation of why hot air/water isn't available at idle makes sense now.

I know there is no temperature controlled valve on the heater matrix entry - I presume the heat control just moves a flap/valve to mechanically limit the amount of hot water entering the matrix.

Makes me wonder is this one reason why the water pipes on the RS2 have a slightly different layout to the S2.

I probably need to draw them both up to explain better.

[Nuvo]

I know there is no temperature controlled valve on the heater matrix entry - I presume the heat control just moves a flap/valve to mechanically limit the amount of hot water entering the matrix.

The flap doesn't limit the flow of water into the matrix, the matrix is always full. Surely it limits the flow of radiated heat from the matrix?

[johne]

Paul,

I can't speak for the RS2, but I can't see why it should be any different. On the S2, the heater matrix is fed directly, in fact the two solid plastic pipes that stick out of the bulkhead that the hoses from the engine connect to go straight back onto the top of the heater matrix.

When you turn the temperature knob on the heater you're moving a flap that directs the air coming into the central heater unit either around the heater matirx (fully cold) to all through the heater matrix (fully hot) to a varying combination of the two.

No water valve or restriction is involved so the heater matrix itself always has a full water flow. In the summer when you've selected cold, the heater matrix is sitting there full of hot water from the engine but with no air flowing over it. In reallity some heat must escape which is why one of the guys in the USA posted about modifying things to turn the water flow off to the heater matrix with a valve in the summer to make the A/C more effective. In theory fine, but then the only bypass for the water pump with the engine thermostat closed during warm up is the auxilary water pump; which might be a problem.

So, just for the record, if anyone has a leaking heater matrix there's nothing wrong with just joining the two hoses together at the bulkhead bypassing the heater all together. You'll get no heat but at least it'll be dry inside the car and the engine will be fine and no damage done. Let's you put off the evil moment of dashboard out to replace the matrix................

John

[S2central.net]

Ahhhhhh - OK - considerable more enlightened then on the subject of heaters and stuff.. Can you tell I haven't spent anytime thinking about this ?

Because tonight ....................

I have been mostly searching for more ECU maps - and I think I've cracked something nice that has bugged me for about 7 years. Helped considerably by studying an Opel chipset - too bizarre to explain - watch me delete this post later if it turns out to be another false dawn... But I've found the same code sequence in RR, 3B, AAN, ABY & ADU in relation to this. Rushing out to the garage with an emulator to verify this at 1am might somewhat upset the neighbours though... Maybe on the school run though - LOL... I need some sleep - no more binary fog tonight.

[Fat Audi 80]

Paul, I had very similiar syptoms and a small amount of coolant loss. The heater would blow warm and cold and never really felt constant. This was down to a leaky afterrun pump, which was potentially depressurising the system and maybe letting air in.

Check that and also for any other leaks. (I had to get the engine up to temperature and "twist" the afterrun pump to see the tiny leak in the body). Be Careful!!!

Once that was fixed, the cabin now heats up in literally a couple minutes to really hot air...

HTH

Cheers,

Steve.

[Error404]

Don't do an Andy Casey and scorch your face off

[Jonnybravo]

My ABY is no different, on several forsty nights I've started my car up and left it idling until its warm so I can deforst the windows and to my suprise I've got in and its still about -10 inside even though the car was at running temperature. As soon as I go for a drive it the heaters started working instantly.

I've not long fitted a new QH thermostat and bled the system correctly but I have found a bit more air in the system if I try to bleed it at the heater matrix pipe which even when you get sorted comes back after a few k ?

Good info above though, I'll admit the fault has only started since its got colder so it might just be that