Heater matrix bypass

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Bison535
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Heater matrix bypass

Post by Bison535 »

Water leaking onto drivers side ( LHD) foot well probably from heater pipes?!? Or heater matrix, very difficult to see where it’s leaking? Expansion Tank level dropped and red temperature warning light flashes.Please advise best stages of investigation and hopefully repair? Maybe try to bypass heater matrix!?
Any help appreciated
VW t25 1.6 TD 1990

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Oren Kipnis
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Re: Heater matrix bypass

Post by Oren Kipnis »

The hoses of the heater matrix enter at the right hand, so probably the leak originates from the matrix itself.
1990 ex. German Army Syncro, 3 knob, AFN, M469 fully converted to 16". Camper conversion by URO CAMPER in Seville.

cobblers
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Re: Heater matrix bypass

Post by cobblers »

Also, there are no joins in the hoses other than where they attach to the matrix, and they don't travel far within the cab. The leak is unlikely to be a hose.

If you definitely have coolant in the footwell, it is almost certainly due to the matrix. On the off chance that it isn't the matrix, you need to remove the dashboard to do the repair anyway.

First of all, confirm that the water in the footwell is definitely coolant, and then start removing the dashboard...

Bison535
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Re: Heater matrix bypass

Post by Bison535 »

Thanks guys for your informative responses 👍 The removal of the dash is quite a task which I’m not keen to undertake 😩 can I ( how can I ) bypass the heater matrix?
VW Vanagon 1990 1.6 TD

JeffRoo
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Re: Heater matrix bypass

Post by JeffRoo »

Honestly the dash isn’t too hard to remove. I’ve currently got mine out as needed to replace the blower motor. Loads of videos on the u tube will show you the way. It’ll be out in less than half a day. :ok
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Oren Kipnis
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Re: Heater matrix bypass

Post by Oren Kipnis »

Bison535 wrote: 28 Dec 2025, 18:38 Thanks guys for your informative responses 👍 The removal of the dash is quite a task which I’m not keen to undertake 😩 can I ( how can I ) bypass the heater matrix?
VW Vanagon 1990 1.6 TD

You can bypass the heater matrix from underneath the van.
Once the spare wheel is out of its holder, you can see the hoses stepping up into the cabin close to the gear shift box.
On one of the hoses you will note the heater valve, and the are connections for both.
Just arrange a "U" shaped pipe in the correct diameter, and the task is easy.
1990 ex. German Army Syncro, 3 knob, AFN, M469 fully converted to 16". Camper conversion by URO CAMPER in Seville.

Bison535
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Re: Heater matrix bypass

Post by Bison535 »

That’s great advice and thanks 👍I just need to get a hydraulic lift to get myself under the van, it’s a tight area !!

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R0B
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Re: Heater matrix bypass

Post by R0B »

A pair of ramps will be all you need. Or a hole in the ground.  :wink: :lol:
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Bison535
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Re: Heater matrix bypass

Post by Bison535 »

I’ll have to check around for best option 😄🙋🏻‍♂️Thanks 👍🙋🏻‍♂️

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