3.8 FHC: replacing metal heater pipes behind the bulkhead

[paydase]

In parallel to my heater box restoration now being addressed, I observed during its removal that the ends of my metallic heater pipes behing the bulkhead are totally rotten (corroded and obstructed).

I need to consider what to do now, knowing that replacing these pipes with new ss pipes provided by the usuals is a pita.
I found a couple of previous threads on the issue but with no details on how to actually proceed.

Is this a feasible work on a car that is not an empty shell?
If so, what are the openings to be used to insert new pipes and having them aligned and rightly inserted in the holes for riveting?
(I wouldn't like to remove the windscreen and/or the whole dashboard)

As an alternative, is it easier to route new hoses or tubes behind the block in the engine bay and to have the heating valve suitably connected to the cable mechanism coming from the dashboard?

Any advice again welcome

[cactusman]

Think this thread will answer your question...as deep thought once said....' you know you really are not going to like it'...

viewtopic.php?f=3&t=5298

[politeperson]

Or this one, without removing the screen or dash.

viewtopic.php?f=3&t=9852&hilit=dreaded

[ralphr1780]

On a LHD the dash top and speedo/tach facia have to come out first, and the wiper rack too.
Be prepared to leave adn traces all over.

[paydase]

Thanks everybody for the very useful comments and links.

I realise that the job is out of the scope I was considering and I will let it on hold for the time being.

I will instead explore the alternative of routing hoses/pipes in the engine bay between the block and bullkhead.
Any tip, from those having done it this way, for keeping/making a functional cable command of the heating valve?

[paydase]

I have been looking around for options to replace the piping behind the bulkhead by piping inside the engine bay.
The most tricky issue seems to be the heating valve, being attached directly on the firewall with one of its ducts going through the wall.

I think that maybe it could be solved by replacing it with the S3 heating valve which is attached on the top plate of the heater box, with its two ducts parallel and directed towards the engine as shown on the pic.
Also it seems that the command cable is long enough to be usable with the current cable hole on the firewall.

Three questions:
- did anybody already try to use an S3 heating valve on a S1, could it work?
- are the piping diameters the same than for the S1, for using S1 or S3 hoses indifferently?
- is there no specific issue regarding the cable command?

[johnetype]

There are several in-line heater control valves readily available, notably Audi 80, Golf Mk1 and later classic mini. These all have 5/8" (16mm) diameter pipes iirc but as the pipe sizes change anyway around the heater circuit you will have to accommodate that whatever.

The heater valve can be anywhere in the circuit and the Bowden control cable extended to suit. I currently have no heater so I've looped the coolant outlet from the rear of inlet manifold back to the port behind the water pump. I've included a Golf in-line heater valve just behind the water pump at the side of the distributor to regulate the flow otherwise you've effectively got a full on permanent thermostat bypass. The heater valve diameter matches the water pump inlet at this point and is discretely hidden so as not to offend the eye or purists

The same arrangement but with the flexible hoses extended direct to the heater matrix pipes would of course let you bypass the pipes in the bulkhead completely and still control your heater.

[Hugo]

I replaced mine with the screen out & the top of the dash off. It was a doddle. The only advice I can offer is to trial-fit the pipes from the front first, to make sure they actually fit through the holes!

[paydase]

Hugo, you may be fairy-fingered...
After having seen the following video on jaglovers, I don't feel confident to engage in that job:

John, thank you for the tips.
I have looked at the inline heater control valve model you refer to and have seen mixed feedbacks, maybe the plastic kind of construction.

I have however found a brass model that seems quite robust, with a possibility maybe to use the current valve attachment holes on the firewall, and a command by a bowden cable that I may suitably route with a 3/4 turn loop of the cable above the heater box to also use the existing command hole in the firewall.
This model exists in several diameters and push/pull configurations (pic attached)).
https://www.ebay.ie/itm/Brass-Heater-Va ... 2031068354

A few additional questions:
- seems to me that all the metal pipes of the heating circuit (from the exit of the inlet manifold back to the return rail to the water pump have a 12-13 mm external diameter, so would a 1/2" diameter valve (not 5/8") be the correct one?
- should I take the push to close or pull to close model (could not verify that yet)?
- do you recommend making preferably mostly a copper piping circuit in the engine bay or alternatively mostly using rubber hoses (this may be easier to route if flexible enough but I have not found that kind of hose sold by the meter by the usuals)?

Finally I do not understand why in your current system that loops the back of the inlet manifold to the rear of the water pump you need to use a heater valve to regulate the flow.
I thought that by making such a loop the thermostat would actually always be inline in the circuit and not bypassed at all? Am I totally wrong?

[Hugo]

Hugo, you may be fairy-fingered...

Ah, but I had the egine out, windscreen out, dash top off......

[Hugo]

I watched part of the video - it's a lot easier without the screen, as you can reach over the top from the engine bay.
A lot of it is in the mind - if you think it's going to be a real struggle, as I did, you may be pleasantly surprised at how easily it all goes together - once you've worked out which pipe goes where & checked that both ends will go through the holes at the same time of course. If the screen is still in place, I'd be inclined to run a piece of string through the pipe & poke it through the holes in the bulkhead, so the pipe can follow the string through.
It's really not that bad a job - just take your time & do one pipe at a time. I wouldn't recommend riveting one end in place before the other end is through the hole though - a jubilee clip over the protruding end will hold it while still giving a bit of wiggle room.

[Durango2k]

Hes, its a 3.8 E-Type, and you are valueing it down with that kind of „work“. Do no longer put any effort in avoiding the inevitable, go there and do it right. Or have it done.

Carsten (scrooge mcduck).

[Series1 Stu]

I agree with Carsten. The car deserves to have this done correctly. Use well made stainless steel replacements and the repair will outlast you and the car.

I would consider your proposal to be a bodge if viewing the car with a view to purchase and would be left wondering what other short cuts had been used.

The amount of time and effort put into finding an alternative would probably be greater than the time to do the job properly anyway. Then you probably wouldn't be happy with it after all the work.

I'm usually the first to tell people that it is their car and they can do what they want with it but in this case it does just seem like a bodge.

Regards

[politeperson]

I agree with Carsten and Stuart,

Just get stuck in!

[paydase]

Stuart, I have no intention to sell the car but enjoy it. My idea was to put the cat back on the road quickly and to do the correct reconditioning later.
But thank you all for your "hardliner" encouragements, new food for thought...
I will reconsider my approach

[ralphr1780]

Serge, I understand your hesitation...the further you dig the longer gets the to-do list.
And in your case since the car has still engine/dashboard/windshield fitted, the heater system restoration is inevitably a big time consuming job.
You could indeed well, if you plan to do some deferred major restoration work, fit temporary piping and valve in the engine bay and continue using the car. The positive side is that any coolant leak would be visible and with limited damage.

[Series1 Stu]

Or, if you're not bothered about the heater for now, bypass the heater system by simply connecting the manifold outlet to the pipe that runs under the manifold. Job done!

The car gets hot enough without the heater anyway.

Regards

[paydase]

Stuart, I think I will do as you suggest for now, quick and easy, postponing the correct rebuild for later.
But John (johnetype) said in post n°7 that he included an in-line heater valve just behind the water pump to regulate the flow to avoid a full on permanent thermostat bypass.
Is a valve needed/preferable in the loop (or not) if I make a bypass or can I simply connect the pipes as you suggest?

[johnetype]

Serge, you can connect the hose as Stuart has suggested and in the winter it would probably be no issue. However, if you do just loop the hose a proportion of the hot coolant exiting the inlet manifold will be fed straight back into the engine at the water pump having bypassed the thermostat and the radiator to be cooled and increasing the chance of overheating.

I don't know how significant a proportion would flow this way but given it will be a lower resistance path than out through the thermostat and the radiator it could be significant so that's why I included the heater valve to limit or turn off the flow.

The alternative is to plug off the outlet on the inlet manifold and plug off the return pipe going into the water pump. The challenge is that it's easier to join the two connections with a length of hose than it is to find something to cap them off.

[paydase]

Got it.
Thank you, John