I have managed to get some drawings on the heating system and it seems that only one fan and 4 servos and it looks like it could be a servo fault which means I will have remove the dash
Ongoing Cabin Heat Issues Matrix
- Thread starter Compo1
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Hi there - Did cleaning the egr fix the issue for you? thanksIt's going to remain a mystery this one then.
Annoying
I flushed the egr cooler and the water side of the egr the flow was in my opinion was good, at various stages trying to solve my issues i thought i was sorted, at one point id great even heat from the all vents. Sorted i thought. I thought id cured it with the blocked pump and obviously that helped a lot but was not the total fix, although my cabin was red hot.
After that at the next regen it lost another header tank full of coolant, i was pulling pipes all over looking for restrictions or blockages yet again after doing them once before, i removed the pipes at bulk head to the head and egr cooler for a better look. The top pipe has a smaller, thin pipe on the same coupling. This is the return to header tank pipe from the matrix, it has a one way valve in it and i think this is responsible for returning for any overpressure in the matrix, this return valve on mine flowed both ways not one way which was to allow flow to the header tank from the matrix and not back. My thoughts are as the systems pressure rose higher during a regen the pressure was flowing back towards the matrix through the faulty valve causing all sorts of issues localized boiling etc.
I replaced that pipe system and touch wood i can say with confidence it has cured it.
Although every time i put that in print it does it again.
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Interesting feedback - these cooling systems are soo complicated, with many one way valves, pumps and heat exchangers!
When I had my blocked matrix, I also noticed my tank pressure relief cap was weak and letting go at something like half or two thirds of its marked value. Easy to test by blocking off ports on the tank and pressurising it with a bike pump and gauge.
I also think for me a key thing is the length of time it is taking for cabin to heat up - cabin takes a long time to heat which makes me think there are more blockages
After cleaning out the crystal salt like stuff from the auxiliary heater pump and the low heat circuit pipework i could get warm air starting to come through within a couple of miles. At cold the main coolant circuit is cut off by the main water pumps shroud been closed, at that point the auxiliary heater pump is working by pumping exhaust heated coolant from the egr cooler on diesels anyway through the matrix.
I feel your pain mate, ive had it rough sorting mine as there were various problems that were not just down to a blocked heater matrix. I've learned stuff along the way.
I'm very surprised my hair line is how its always been, ive lost sleep over this issue but im too stubborn to be beat, think most would have shipped it off to webuyanycar
I did yeah, but if you read this thread it was a combination of problems, not just a straight forward matrix issue.
Hi,Well i thought i would close this problem and show you the cause.
My heater support pump and pipework to and from it was full of this stuff. See pic. It is neither gel from the bag it's not had one for 5 years or casting sand. Its like a brittle, compacted salt.
Ive spent the last day and a half removing pipework on the low heat circuit, including the metal ones to blast them out.
What a job
Anyone come across this ? I'd love to know what and how?
View attachment 45865
Did you ever hear water gurgling/sloshing noise from behind your middle vents/dash when the ignition was on and/or when you just turned the car off after driving.
My issue is these noises and my coolant tank was not holding pressure. Either coolant was being dropped back into the system or it was at times being pushed out the tank because too much pressure was building up.
I went underneath my car to do an oil change and my ignition was on for whatever reason and I heard the same water sloshing about noise from that heater support pump that is next to the oil pan plug. So I suspect it is that pump that is going bad or has gone bad??? Any pointers would be appreciated. Thanks.
If you hear that gurgling, it usually means air is in the system. Some garages don't even attempt to bleed this really tricky system properly, which involves VCDS and a vac fill, these garages are still running cars up to temp and squeezing pipes. It's no good doing so on these. For me as a home mechanic, i avoided that by vacuum filling the system then running the VCDS bleed sequence.
If you're not in a position to vacuum fill then speak to a competent VAG specialist and ask for a Vac fill and VCDS bleed.
I tested both my pumps by removing them and a direct connection to a 12 volt battery with pipes into a bucket of water. These pumps if they fail, fail mainly because the plastic impeller becomes loose on its drive shaft. They can fail electrically but from my research rarely do. If either pump has issues and is not pumping correctly, you will get localized boiling of the coolant which in turn over pressures the system and out the coolant bottle it goes.
Hi,
Thanks so much for your response. I bought a pressure test kit and I pressure tested the car. It did not hold pressure properly as it was dropping a bit.
Aside from that I have got a vacuum filler kit which came with my pressure test kit but I do not know how to use it and before I refill coolant under vacuum I would have to drop all the old coolant and bleed the system dry and I do not know how to do that.
My mechanic said that the whole bleeding the system dry and the filling it under vacuum is for much more modern and high end cars. I however disagree with that as my car's coolant system looks to be very complex.
Just for reference then, do I go to a reputable 3rd party VW garage and tell them the following:
- Bleed the coolant system using VCDS
- Refill coolant system with under vacuum
Also I would like to know how did these random air pockets get into my system? I thought the system was meant to be a closed system. Does this mean that I have an eternal leak that is allowing air to flow into the piping?
As mentioned above, I ran the pressure test and I was not seeing any visible coolant leaks and/or drops on the floor. But pressure isn't being held properly??? So confusing!
If your cooling system won't hold pressure - this is the FIRST problem you should address.
I would double check your pressure tester to ensure it is a real leak and not just the pressure tester leaking but supposing your tester is air tight, first thing to do is find the leak.
To name a few possible culprits:
main coolant pump
heater matrix o-rings (mine leaked and wet the carpet as had gone square)
radiator + pipework/o rings
air to water heat exchanger (as mentioned can check with a borescope, I found water in mine but must be a small heat dependant leak as mine passes my pressure test)
egr cooler
head gasket
These cooling systems are very complicated with 3x pumps and many one way valves.
Normally, vacuum fill tools need an air line supply - and work via the venturi principle - blowing high speed air past an orifice creates a vacuum.
First empty the system.
Then pull a vacuum.
Then open the valve on your vacuum fill tool - which sucks on the tube submerged in your bottle of coolant and fills your system only with coolant (don't let this tube suck air!).
Once is stops sucking, top off the header tank if required, and then you do the VCDS bleed as a final step.
Hi,
Thanks for your reply. In the end of your response you mentioned about refilling under vacuum and then bleeding. I would have thought that I need to bleed the system dry first using this VCDS and then after that fill the coolant system under vacuum?
Or is VCDS bleed isn't the same as bleeding the system dry?
The VCDS bleed routine is just an automated routine which cycles the various pumps as the engine gets upto operating temp. The vacuum fill is the first & important part.
In theory, if you vacuum fill correctly there will be no air getting back in to the system.
VCDS bleed may not be needed, i did it as i have whats needed to do it.
VCDS bleed may not be needed, i did it as i have whats needed to do it.
Hi,
I rang a good VW specialist garage (they did my heater matrix 5 years ago), I told them this and they said that they only replace the coolant under vacuum but the VCDS isn't that needed.
I am thinking of biting the bullet and get a full coolant bleed and refill done by them. It will cost me almost £100.
However, what is on my mind is that how did air randomly enter my system anyway? I did not have any work done to my car months ago when the water gurgling/sloshing noise started. So is there a leak somewhere? Because that means that it will happen again after getting coolant refilled.
Any ideas???
Take the under tray off any coolant leaks will most likely show up on it, if air is getting in coolant will get out. Look for damp areas on and around the coolant pipes. Check the footwells in the front of your car are not damp.
You could also do a pressure test on the coolant system with the same bleed kit to see if it holds pressure, if not there is a leak.
Hi,
Yes, thanks for your input, very helpful.
I have checked for coolant under the car, there is never any coolant there. Also ran the pressure test and there were no leaks, as this was done in the garage and nothing was falling on the floor........... BUT THE PRESSURE WAS NOT HOLDING. IT DIED DOWN A BIT AFTER A FEW MINS.
Just for reference I pumped it up to 15 PSI.
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