Heater R,R & R

Heater Removal, Rebuild & Replacement

The heater in the Mk3 was not working.  The valve on the heater radiator was seized closed and leaking, so here I will step through taking the whole unit out, dismantling and rebuilding it.

The left side of the unit has the various air & water controls and cabling.  The parcel tray below the glovebox has been removed here.

The bottom-centre part of the dash must be removed, along with the handbrake.  Be careful not to lose the ratchet tabs & their small spring when withdrawing the handbrake handle after disconnecting the cable.

Now you can see the heater unit clearly.  There are only six bolts (all relatively easy to get to) holding it in - plus the de-mister tubes, cables and hoses to disconnect. Keep a container & cloths under it to prevent coolant (or in this case, rusty water) staining the carpet.

Foam on the demister flaps and around the radiator has all perished and disintegrated.

There was a lot of debris in the heater.  The case comes apart easily (heaps of self-tapping screws) and then the radiator can be removed.  Lots of perished foam inside the unit too.

A  better look at the seized valve.  Once I had supported in the vise and got a good grip on it, I was able to free it up enough to remove the guts of the valve - it just pulled right out.

The "O" ring seal was compressed & perished.  Got a new one, flushed the radiator with large amounts of high pressure water, cleaned and lubed the valve with vaseline.

This is the air inlet at the base of the plenum chamber (under the dash).  Foam seal has disintegrated here too - must be scraped off & cleaned up.

I got a roll of foam and some closed-cell foam tape from Para Rubber.  Cut out the shapes for the heater/demister flaps and for the sides of the radiator where it mounts inside the case.  All glued in with Ados.

Heater case reassembled and with new foam tape around the air inlet where it seals to the base of the plenum chamber.