Lack of heat, I think I know why. What do you reckon?

[jonner_dub]

Hello Everyone this must only be my 1st or 2nd post. My name is Jon i own a mk2 golf gti 8V, and a type 2 bay window devon conversion, hope your all doing well?
Firstly many thanks to all of the great posts that I have been using to help me try to get to the bottom of the current issue i am having with the drivers heating system.  I have used the previous posts on this subject to get me this far but now I have a few questions. Below i will breifly outline what i have investigated and found out, along with any questions.


Heat Up Test
Firstly i have run the engine until the digital engine oil temp read 98, at this temperature the dial on the dash for water temperature had climbed off its stop just beyond the big white area but before the red light . At this temperature the fan kicked in for a couple of minutes.

•   There was sufficient coolant in the header tank
•   Radiator pipes, top and bottom were hot
•   Inlet and Outlet pipes to Heater Matrix (positioned close to bulkhead) were hot
•   Bypass pipe running between ali bodied bypass valve was hot
•   Going inside the car there are no leaks in the footwell from the Heater Matrix
    
Question 1. – Does this test show that the control systems and coolant system is in order and that i dont need to do anything with the components checked above? Or have i missed something really obvious related to the heater matrix or bypass valves?

Heat Control on Dash Board
During the above test the dashboard control is used to turn the fan on and set to hot, but only cold (not freezing) air is availble. This is true when either the control levers on the dash are moved or by manually moving the mechanisms at the base of the plastic cover that surrounds the heater matrix
Question 2. – is the wire with the blue outer sleeve controlling the temperature setting?
Question 3. – are the two wires with black outer sleeve controlling position of air flow (face, windscreen, feet)?

Control Wires and Plastic Cover that surrounds the Heater Matrix
Having removed a lot of the dash and gearleaver cover i started to investigage the cover surrounding the Heater Matrix.
Located at the bottom of the cover surrounding the heater matrix, are levers to which 2 of the 3 control wires are attached. (3 plastic geared teeth components are actuated by the lever) The lever to which the wire (with black sleeving) is attached however this only moves about 2-3mm and it feels like there is a lot of resistance!
Please note all trials moving the black sleeved wires were done at the point where the wires connect to the plastic cover around the heater matrix not at the control lever on the dash!
 
Having removed the facia on the dash where the heater controls are it was obvious that the black sleeve wires are not connected to the control unit on the dash. In the recess in the dash and you can see that the wires are not conected to lever. The only wire visible is the one that attaches to the geared teeth mechanism at the bottom of the platic cover of the heat exchanger. The wire that is mounted at the back of the plastic cover of heater matrix does not even appear to be there!
 
Question 4– Could this be the casue of the problems with my heating system? I have heard that foam etc can come off and stop the control flaps working properly
Question 5- Can the control wires be easily re-attahced to the control on the dash and does anyone have a picture of this set up?
Question 6- Is the plastic cover easy to remove without disturbing the heater matrix?

Really sorry for all of the questions, but I am hoping that some helpful souls out there will point me in the right direction.
Any help with this will be greatly appreciated. I had tried to attach photographs to help with the explanation but could not get them to work!

Many thanks 
Jon

[Thom89]

The heater matrix remains hot all the time the cooling system is hot, thats normal...

The temp control slider on the dash, via cable, opens a vent on the box that contains the matrix

The direction control slider, operates flaps in the ducting, after it has passed through the heater box that contains the matrix

Sometimes the cables can get hooked up on themselves, and simply bind up, or the retaining clips on the cables can break, if someone has previously been heavy handed, cables should also fall into place, and be obvious where they fit

The bypass valves are temperamental,  and can be discarded if a later quality matrix has been fitted. They were fitted after sale, because of a batch of faulty matrix's were fitted by the factory, and in very few cases, were known to dump hot water into the passenger footwell, my personal opinion is that they are more trouble than they're worth, and can be discarded, but the owner has to make that call!

So, if hot air supply is intermittent, then its likely to be the valves. If there is no hot air at all, its likely to be the flap stuck in the closed position... Or both!

Thom

[devilscaff]

If radiator pipes top and bottom are hot does this not mean the thermostat is shot? shouln't only the top one be hot.

[jonner_dub]

Thom & Devilscaff, Firstly many thanks for your speedy reply that is great.

Thom
If i do get rid of the bypass valves i would plan to replace the heater matrix with a GSF part 178VG0041 would that be appropriate?
I assume i would also need to replace the pipes in which the bypass valves used to be fitted with plain continuous lengths? Can this be got from GSF?

Devilscaff
I am confused about the thermostat, because the hot water temperature dial did move and the radiator fan did come on? where is the thermostat located?

Thanks again Jon

[Thom89]

Thom & Devilscaff, Firstly many thanks for your speedy reply that is great.

Thom
If i do get rid of the bypass valves i would plan to replace the heater matrix with a GSF part 178VG0041 would that be appropriate?
I assume i would also need to replace the pipes in which the bypass valves used to be fitted with plain continuous lengths? Can this be got from GSF?

Replace only with a "Behr" branded Matrix, available from GSF I believe, disregard the cheaper alternative... they leak! the one they supply you with should be a Mk3 unit, the same, but uprated,
Without going into my garage, and uncovering my car, I cant remember off the top of my head how the heater pipes work with the valves, though it should be obvious when you look, you maybe lucky, and remove the valves from the system, and just re connect the hoses to the matrix, or at worse, you have to put a join in the pipes to extend them to reach the matrix... You can use 15mm copper pipe and some nice stainless steel crimped type clips to make a neat hidden joint (rather than shoddy Jubilee clips)

HTH

Thom

[mk2bal]

Its a valeo matrix from gsf (more expensive one of the two), same as the one I removed from my step dads car to replace.. Hoses with no valves can be had from vwheritage cheap enough.

[Thom89]

Valeo is fine, as long as the cheap version is avoided

Thom

[dubber36]

I was getting no heat in the car. The pipes on the engine side of the by-pass valve got red hot, but on the matrix side were only luke warm.

I figured that if the water hadn't been following properly through the matrix, that would probably be all clogged up too. So I  changed my matrix for a Valeo one and took out the by-pass valve. I replaced the cut hoses with these http://www.veedubmachine.co.uk/index.php?main_page=product_info&cPath=3_20_77&products_id=678

Now it gets like a furnace in there and there are nice new original looking pipes where the by-pass valve used to live.

[clipperjay]

I think in the OP's post everything sounds normal to me?
The only thing he actually has an issue with is the diverter flap or cold air dirverter flap.
Like Thom said they can get stuck or slip a cog gear setting which means as you slide the cooling bar the cables arent moving freely enough to open or close the flap to block the matrixs' heat off from the air circulation system, or open enough to get decent heat off the matrix.
The flap has usually a foam backed type that perishes I used neuroprene sticky foam on mine to ensure the seal and flap completely isolates the heat from the whole heated system. (The flap has holes by the way)
Either way crack it out and inspect you will see pretty right away whats going on, but you could just spend a fiver on some foam instead of £50 odd pounds and a lot of cut hands and swearing for no reason at all!
Even disturbing a 20 year old heater matrix could cause unnecessary damage to the rad fins!
If you want to see what I've been talking about just click on my heater matrix how to guide!
http://www.golfgtiforum.co.uk/index.php?topic=68989.0

[jonner_dub]

Evening All

Firstly another massive thanks to you all for responding to my many questions it is massively appreciated

Clipper Jay that is an awesome guide, thank you so much for sending over the link.
I am definitely going to attack the plastic cover around the heater matrix first to get inside it to access the diverter flap. I personally think they have slipped on the cog gear. However they also seem quite fragile so i dont want to force them! (Any tips). Also interesting to see the picture of the control levers as that should show me how to re-attach the wire on mine that are currently hanging free.
This seems to be the obvious problem at the moment so will try this and then if this does not solve the issue then i will have to tackle the bypass valves and heater matrix and all the injuries this will induce!!!!! 

I am afraid i might have a few more questions as i progress with the repair!!

Thanks again everyone.
Jon