Front Heater Leaking

[viking]

Vehicle Sharan 1997 1.9 TDI without air con.  The front heater has developed a leak. Screen mists up immediately if heater turned on. The front carpets are dry but moisture is felt underneath heater ducts. I know this is a big job and involves removing the complete facia, steering column etc... I will attempt this before autumn.  Before ordering a replacement heater matrix I need to know a few points regarding the control of coolent flow. Is the matrix sealed with just a flow and return pipe ? How is the water flow controlled as it may be the control valve leaking instead of the matrix. I'm unable to get any clear diagrams to show these details.

[viking]

^{I've found the answer to my question.....  a Youtube video clip showing a VW Passat heater box being removed clearly showed that there is no coolant  flow valve. The heater matrix has water flowing through it regardless of hot/cold control. Heat is regulated solely by air flow flaps and blower motor. Need to source a front heater matrix. Best price I've seen for a new one is}

[sparky Paul]

A new one is about 37 quid from a seller in Poland, on that well known auction site.

[viking]

Bought a front heater matrix from www.adrad.co.uk  just over

[viking]

I successfully changed the heater matrix over the weekend. Spent Saturday and Sunday 08.30 to 19.00 on both days to complete !  Had a few moments when I thought I'd been defeated but managed to win in the end. The wiper gear needs to be removed, steering column unbolted / moved down to give clearance to remove facia. Facia cross member strut needs to be unbolted and shifted forwards about 3" to allow the heater unit box to shift forwards. This allows the heater matrix pipes to clear the bulkhead. The heater box need not be removed as the matrix slides in through the top. The matrix I bought looked the same as the old unit but did not fit in. There was a lip around the top preventing it from sliding fully home. Ended up modifying the top of the box. Just needed to remove some plastic around the top. Delayed the job for an hour and a half.

The awkward stages were removing the steering column shear bolts. No clearance to get a drill in straight. I propped up the facia with a block of wood. This gave enough space to get a hammer and cold steel chisel in to knock the bolts round. They're not so tight. I was able to re-use the bolts again, just nipped them up using same method. The 10mm nuts (3 in all) holding the heater box to the bulkhead were very awkward to remove. Accessed from the engine bay, 2 were blind and recessed. Apart from that it was straight forward. Worth bagging and labelling screws as you go. Take pictures to help reassembly.