Heater Matrix question

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ThomasD
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Heater Matrix question

Post by ThomasD » Thu Dec 18, 2014 3:45 am

Hello Guys,

I've noticed a slight smell of coolant when I turn on the heat in my Scirocco. It seems to disappear after a few minutes, but it is there at first. I can't find any evidence of a leak in the engine compartment and there is no smell if the heat isn't on. There is no obvious leak in the cabin - I've checked the carpets and around and under the blower box. But I suspect the heater matrix may just be starting to leak very slightly. I think I should probably replace it before it gets worse.

I had a quick look today - by moving the center console forward and removing the parcel shelf and sound panel, I could access the heater matrix cover on the passenger side of the car. But I'm not sure how the heater matrix can be removed. So two questions for anyone who may have done this job:

1. What is the best way to disconnect the hoses? Does it make sense to disconnect them in the engine bay first, release the clips on the heater matrix and pull the hoses from the engine bay side? Or is there a better way?

2. Once the hoses are off, is there enough room to just slide the matrix out? I see there is a bracket - looks like a dashboard support - on the passenger side - I don't know if there is enough room to actually get the matrix out because of that. Or does the whole blower box need to be removed in order to remove the matrix from inside it? If so I'm assuming that makes the job much more difficult...

Thanks!
Tom


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Little_bro
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Re: Heater Matrix question

Post by Little_bro » Thu Dec 18, 2014 7:59 pm

Before you remove your heater matrix. Have you tried rad weld- sealer?



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Re: Heater Matrix question

Post by DannyH » Fri Dec 19, 2014 12:22 pm

Rad Weld worked on mine.


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Re: Heater Matrix question

Post by mark1gls » Fri Dec 19, 2014 10:28 pm

I would not use rad weld as it blocks every thing up and leaves gunk every where, it's best the solve the problem than boge it up.


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Little_bro
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Re: Heater Matrix question

Post by Little_bro » Fri Dec 19, 2014 10:45 pm

I find the trick with coolant sealants is first a good flush with a flush agent and then not to overdose with the sealant. Or even better pressure test your car
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Re: Heater Matrix question

Post by Nate » Sun Dec 21, 2014 10:54 pm

before you start spending money... is the car actually loosing any coolant?

next up, any form of sealant (k-seal, radweld etc) is a bodge, and should not be viewed as a permanent repair. although it is designed to only set when it comes into contact with air, it can and will congeal inside the system, and will block the small tubes in radiators and heater matrices, also seen it block 1/4" coolant pipes. this leads on to reduced performance of the cooling system, overheating blah blah headgasket blah


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ThomasD
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Re: Heater Matrix question

Post by ThomasD » Mon Dec 22, 2014 1:57 am

Nate wrote:before you start spending money... is the car actually loosing any coolant?

next up, any form of sealant (k-seal, radweld etc) is a bodge, and should not be viewed as a permanent repair. although it is designed to only set when it comes into contact with air, it can and will congeal inside the system, and will block the small tubes in radiators and heater matrices, also seen it block 1/4" coolant pipes. this leads on to reduced performance of the cooling system, overheating blah blah headgasket blah

As far as loosing coolant - no, not that I can tell - the level looks fine. And no wetness on the carpets, etc. But the smell is definitely there when I turn the heater on. My "theory" is that when I start circulating the hot coolant through the heater matrix, there may be a very slight leak - maybe a pinhole - it doesn't take much coolant to be able to smell that distinctive odor.

My concern is if the heater matrix is starting to go and I just wait until it gets worse, I might end up with a big mess inside the cabin with coolant soaking the carpet and the sound insulation and that will take a huge amount of effort to clean up and get rid of that smell.

It would be nice if the heater matrix was easier to access and inspect.

My feeling on leak stoppers is that they are useful if you need an emergency fix, but otherwise it's better to repair/replace the items that need attention.

Thanks!
Tom


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Re: Heater Matrix question

Post by mr.brown » Mon Dec 22, 2014 8:37 am

I've only ever done this job the "hard" way - which is by removing the entire heater box. It's been a while but from what I remember the whole unit is held in by the 4 screws visible under the scuttle panel cover.

It's a matter of removing the centre console and shelves, removing the heater cables, ducts and motor wiring, undoing the hoses in the engine bay and then removing the whole unit downwards into the car. It also helps if you loosen the dashboard too.

Do you have the Haynes or Bentley manuals?



ThomasD
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Re: Heater Matrix question

Post by ThomasD » Tue Dec 23, 2014 10:43 pm

mr.brown wrote:I've only ever done this job the "hard" way - which is by removing the entire heater box. It's been a while but from what I remember the whole unit is held in by the 4 screws visible under the scuttle panel cover.

It's a matter of removing the centre console and shelves, removing the heater cables, ducts and motor wiring, undoing the hoses in the engine bay and then removing the whole unit downwards into the car. It also helps if you loosen the dashboard too.

Do you have the Haynes or Bentley manuals?
Thanks! That is what I was afraid of - it didn't look like there was clearance to just slide the matrix out. I do have the manuals. The Bentley doesn't go into much detail, but the Haynes did mention the process you describe (except for loosening the dashboard).


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Re: Heater Matrix question

Post by james butler » Wed Dec 24, 2014 4:06 pm

This may sound daft but do you have the rubber that presses to the bonnet that separates the engine bay from the plenum chamber?
I ripped mine off once and was damaged so never put it back on. That gave me all kinds of weird smells.
Coolant, petrol and hot oil smell was common.
Putting a new piece of rubber in fixed my issue.


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Re: Heater Matrix question

Post by ThomasD » Fri Dec 26, 2014 2:00 am

Thanks for the suggestion about checking that rubber - it is in place and it's in pretty good condition. But I had never really thought about what it's purpose was until you mentioned that - good to know!!


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ThomasD
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Re: Heater Matrix question

Post by ThomasD » Mon Jan 19, 2015 11:40 pm

I decided to replace the heater matrix. As it turns out, it was a bit time consuming, but not too difficult. The Haynes manual is a good guide.

Here are a few random notes that might be of use to anyone else doing the job:

The heater box does not need to be removed, however, it does need to have to be lowered and rotated slightly to allow the matrix to be removed, so you do need to remove the 4 bolts holding the blower in place to do that.

The coolant needs to be drained, and the heater should be in the full "hot" position when doing that. There will still be some coolant in the matrix even after the coolant is drained, so protect the carpet with some plastic in the cabin, and some old rags or towels on top of the plastic in case any spills while you're removing the matrix from the car.

I did not attempt to remove the heater hoses where they attach to the matrix while the matrix was in the car. I disconnected the heater hoses under the bonnet and removed the matrix with the hoses attached to it. When installing the new matrix, I first attached the hoses, aligned the clamps properly and cleaned and refitted the insulation. Then I installed the matrix in the car and threaded the hoses back through the firewall.

Also, it was much easier to work in the car with the passenger seat removed. The lower console did not have to come out of the car, but I did remove the upper console, radio, and the air pipe going to the far left passenger vent.

There is a small connecting pipe which connects to the lower heater hose. The original pipe was metal. VW Heritage has a replacement (probably a VW classic part), which is plastic so it will not corrode. The part number is 171-121-140D.

The heater matrix is NLA from VW dealers, but the original part was a Valeo part and you can still find the Valeo part. The VW part number is 171-819-031E and the Valeo number is 812034. Meyle offers a slightly cheaper replacement part that is made in China, but I figured the original part held up pretty well. I replaced the heater hoses, which are still available from my local VW dealer and were not terribly expensive (171-820-371B). I also replaced the expansion tank as it was difficult to see through it had yellowed so much. Also available from the dealer (171-121-407F).

There has been some discussion about coolants. The original fill in this car was G11. The only coolant VW carries now is G13. Some people say G13 isn't good for older cars. When I bought my car, it was serviced at my local VW dealer who replaced the radiator and water pump and flushed the cooling system and put G13 in. While I don't think there is anything wrong with the older coolant, I didn't feel like converting back, so I am continuing to use G13 in the car. I did email Volkswagen UK with the question and their response was that G13 is compatible with older VWs like this. I think it's probably more important to periodically change the coolant than to worry about whether you're using G11 or G13.

A few pictures:

Lower shelf removed and heater matrix door removed. There was no evidence of leaking when I just opened the door and took a look, but whenever I would turn the heater on, there was a slight smell.

Image

Original matrix removed - now you can see what I was starting to smell something. (Note - the coolant on the towel came from the disconnected heater hoses, the matrix leak was very slight).

Image

Original part:

Image

Valeo replacement - identical except for the VW/Audi logo:

Image

Things taken apart:

Image

Heater matrix slot in the heater box:

Image

Old vs new connecting pipe:

Image

Original and new VW expansion tanks. Big color difference. The tank was not originally this yellow/amber - it was actually white, or pretty close to white.

Image
Last edited by ThomasD on Sat Jul 22, 2017 1:29 am, edited 1 time in total.


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Re: Heater Matrix question

Post by jakeb » Sun Apr 03, 2016 8:22 pm

I had a right nightmare getting the matrix out so I just chopped the plastic pipes of just before the rubber hose and pulled the remains out afterwards. Definitely repeat the technique if I had to do another.



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Re: Heater Matrix question

Post by sabre0699 » Sun Apr 10, 2016 6:10 pm

Think yourself lucky had to change the heater matrix on my old 1997 Audi a4 tdi , seats out , steering wheel off, remove passenger airbab, centre console and all the electirics , drop the steering column ,the dashboard followed by the cross beam behind the dash before you can reach the blower.

Then the aircon has to be drained before the matrix can be removed, fit new matrix and then reassemble.

Whole job takes about 8 to 10 hours



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Re: Heater Matrix question

Post by Jerry Atric » Sun Jul 23, 2017 5:34 pm

Well, having spent the last few hours wrestling with the under dash area of the car to access the dreaded heater matrix, I came back to ask the question, "can the matrix be removed without taking the whole heater unit out ? " and the answer seems to be here...drop the unit a bit and twist. However, reading jakeb 's answer may be my solution if I can find something to cut through the inlet and outlet pipes of the matrix ; still very inaccessible and the damned clips are facing inwards so nigh on impossible to get the grips on the bits you compress.
If jakeb is still about , i'd be interested to know how and what he used to cut through the matrix in/out pipes with ? I've got a dremel cutter which may be the answer i suspect.

Any other ideas gratefully received.