Just before putting my instrument panel back together, I thought I'd have a probe around with my borescope at the bits you can't see.
Found evidence of some historic oozing from heater matrix O rings, no current drips or signs of leakage.

In the opinion(s) of the forum, do I really have to jump in immediately and do the Audi conversion and take the car off the road for even longer, or can I just continue to monitor for a few weeks?
All opinions welcome, especially the ones that say "continue to monitor"!

I'd bung a pair of O rings in it while it's apart and do the Audi core change in 10 years time when they start to leak.

It's oozing too early!
O rings were replaced in 2011. Original LR ones too, or at least that's what they charged for on the bill...

2nd that. Put new rings in and buy some time with it. Clean mating faces where the rings sit so all is smooth.

So the historic oozing could be from then and the reason why they were changed in 2011. Originals are only £3 so I can't see anyone trying to make an extra bit of profit on the parts......

Have you actually looked at it whilst it's running yet? Or are we all jumping to conclusions about changing the O-rings again without ACTUALLY seeing if it's leaking now?

On second thought, the poblem when tightening the Phillips screw, how tight is tight without ruining the thread or breaking the bracket?
I did it fingertight (a bit more) then wiggled the tubes a bit to make sure they were set and then tightened them. Don't replace the screw for a bolt I think, to not overtighten it.
Bit of a dilemma.

No sign of leaking or even sweating when running!
Time's my enemy here. Need it BOR for 1st Feb and still have to put new gas pipes in and change a few coolant ones to Tee pieces that I'm not happy about
Haven't got dash area even close enough apart to do O rings- shot that pic with my borescope

Martyuk wrote:

Have you actually looked at it whilst it's running yet? Or are we all jumping to conclusions about changing the O-rings again without ACTUALLY seeing if it's leaking now?

The I think you've answered your own question then...

If it's not leaking or any sign of fresh coolant when it's running, then leave it unit it starts leaking... if it does. Just take extra care when doing other plumbing work not to bash the metal pipes about too much.

if you're doing it on your own, then taking the top of the dash off to get the heater core out and put an Audi one in can be done leisurely in a weekend - especially if you have a pre-freed up heater box to refit where the flaps have been looked at and everything regreased etc. So if you do get a leak from the O-rings, then you can address that at a later time - when it's warmer.

My dash is currently fully disassembled, should I be doing these o-rings (and/or replacing the matrix) now? No signs of leaking at the moment.

O rings certainly! Matrix is your call based on condition. They're cheap enough if you get the Nissens one. I believe its part # 71145 (Marty should be able to confirm/ correct me on that) and available on the bay for £27.79

I note the previous mention of Audi, is that a more reliable replacement or something?

Where the original matrix has the O-ring connection, Audi has the pipes on the matrix so you just slide the (longer) hoses over and clamp them.
If it is a plastic piece like big radiators or if they are welded to the matrix I don't know.
Dimensions are almost the same.

I use Nissens part number 70220 for vehicles that I convert. It is like the P38 matrix - in that it has plastic end tanks which are crimped to the metal heater core part (like the radiator has - except tanks are top/bottom)

Instead of having the metal pipes through the firewall, you replace these with a couple of bits of standard coolant hose (if using the 70220 then the outlet fit 19mm hose nicely - which is the same as the pipework in the P38 engine bay, so no additional reducers etc) and some clamps of your choice.

I had to tweak my clamps up after a month or so as things settled in, but with a bit of thought on clamp positioning, you can get it so you only need to take the footwell trim and the drivers knee panel off to get in to tighten them up.

Ultimately it's up to you - I went with the heater core swap as when I went in to do my O-rings when I first bought the vehicle, I pulled out nearly new O-rings, and found the plastic lip on the heater core itself was damaged - so figured I'd swap it when it came out and then not have O-ring issues ever again...

As I have to replace the flexible hoses that go from the heater inlet/ outlet at the engine compartment bulkhead to the metal pipes near the rocker covers via a T piece and want to avoid any strain on my wobbly O rings can anyone suggest a suitable lube to put on the metal stubs/ end of hose? To get a 19mm or 3/4 hose on those things is mega tight, 20mm hose is unobtanium locally and 22mm will be rather loose even though my T's are 20/16/20.
With the old blue coolant (which contains silicates) I'd have used a squirt of silicon spray. With OAT pink stuff being silicate free it doesn't seem right to add silicon!
If the suggestions are stuff I'd be likely to have around the workshop, rather than the cream used by honeymooners (if you see what I mean) that'd be good as I don't particularly want to have to go to the chemist muttering about the missus and hormones!

Washing up liquid...

OR boil some water, and dunk the end of the hose in it for a few minutes to soften it up. Makes getting them on a lot easier, and saved a lot of swearing from both myself and Nick when we were doing the plumbing part of the engine swap.

I usually use the red brake seal grease (known round here as raspberry jam grease) on new hoses so they slip on nice and easily.

Thanks Marty & Gilbertd- hot water/ washing up liquid is a good combo but hadn't thought of RRG.
Not sure I've got any RRG in the shop, but do have some spray rubber lube that I spray my Airbags with if I'm under the car playing around. I'll have a look at the composition of that- suspect it's silicon based though.

I'm sure you'll have some somewhere. My tin looks like it's been kicked around the world at least twice and must be at least 20 years old but it's still just over half full. As it's safe to use on rubber, at least if it's meant to be used on brake seals, it must be safe to use on rubber, I use it on hoses, petrol injector seals and anything else rubbery.

Mace, changing the matrix involves either removing the complete heater unit or cutting bits of steel that get in the way to stop you from sliding it out and then having to somehow re-attach them. Changing the O rings is pretty simple (I've done it 3 times now on different cars and the last time took me 25 minutes) and worthwhile whereas changing the matrix is a only when it needs it job (in my opinion).

Just for completeness, discovered the inlet pipe stubs to heater matrix are 22mm. All the RRG or washing up liquid in the world won't persuade a 19mm hose to fit those!