Water ingress via heater box

[skysurfer]

Just had some work done on my Amazon including the removal and reseating of the windscreen with a new rubber and trims using plenty of sealant. Turned the hose on it this morning and no leaks from around the windscreen. Great. However, I did notice a leak from the bottom of the heater box, so it would appear that water is getting in from the air intake vent somewhere. The chrome air intake vent grill is well seated and the securing holes filled. The water must be getting in from a broken seal somewhere, although I will check the water vent pipe first. Pretty sure its not the heater matrix as it only leaks when being hosed down. Think I'm going to have to take the heater box apart to check things out. Is this pretty straightforward? I'm going to fit a new heater control valve at the same time as mine is shot.....
Thanks for any advice.

[Shsun123]

All the seals are foam on the heater box and can be replaced with ease and are readily available, I have recently removed and renovated mine on a 1969 model , the hardest part of the job removing the washers for the control cables without damaging them , I would recommend if the paint work is tatty or surface rust to blast and re paint while removed and stripped,

[skysurfer]

Thinking of disassembling the heater to replace the foam seals and inspect the heater matrix. Also to fit a new after market heater control valve and paint the heater casing. Is this fairly straightforward from the engine bay and are there any problems that I'm likely to encounter. Cheers.

[Derek UK]

There is a small drain tube at the bottom of the box, inside the car. It drains through an adjacent hole in the floor. This is available from Brookhouse. It often gets broken off, so any water in the box then drains into the car. Note, if the tube is original it has a small plastic spreader bung in the grommet part to make a good seal. Make sure you retain this for use with a new tube as it isn't available new as far as I know. I don't even think it's in the parts book. The box can also rot out at the bottom which then leaks so yours might be a victim of that.

[Ron Kwas]

Skysurfer;

The Drain Hose (45) which drains rain water getting into fresh-air (cowl) vent into engine compartment, and which would not cause leakage into passenger compartment, is shown here: https://weblisher.textalk.se/gcp/20160201-027/ ...and I do not see the interior drain hose Derek speaks of shown, but I agree, that is likely the source of water in passenger compartment...have a closer look in that area.

Good Hunting!

[Derek UK]

Page 704 item #45 on that link. Click to go to the end, 800 plus pages and work backwards!

[sleek lemur]

I had water ingress which caused my foot to slip off clutch. Cause was leaking inlet tap, available from Brookhouse.