Pipe tubing material for coolant

[stugilmour]

I want to install solid tubing on the firewall to clean things up a bit. Car is a LHD Federal Plus 2.

What would be a suitable material that is hopefully commonly available? I spoke with a representative at our local Metal Supermarkets, which appears to be a chain store that can provide pretty much anything you want, and can recommend a fab shop to do any cutting, bending, flaring that may be required.

I am thinking of two 3/4” OD coolant tubes attached to 3/4” ID rubber heater hose at each end. One tube is for the thermostat housing to the heater core top nipple. The other 3/4” tube us for a customized header tank setup. Ideally the selected tubing can be custom bent in a gentle curve to sit tight to the Plus 2 firewall that has a central curved section. Hopefully I can have the tubes bent 90 degrees so I can mainly use mostly straight hose runs to button things up.

The vacuum line on my car has a solid tube that mounts the non-return valve. I am not sure this setup is stock. Although I don’t have the car to hand to check, can someone advise what material would have been used, and whether I could bend it with my hand bending pliers that easily formed the smaller brake lines?

As I don’t have the car to hand, can someone advise on the nipple OD / hose ID for the heater core and the thermostat housing nipples? I vaguely recall the heater core nipples being very tight and the thermostat nipple really loose. Are they actually different sizes? I think I used 3/4” hose throughout the cooling system, but can’t be sure now. The idea is to figure out something better this winter while the engine is removed.

Is the speedometer cable normally attached to the firewall or is it acceptable to leave it loose over the bell housing?

I have attached a picture of my engine bay. Sorry that it is so dark, but you can sorta see the vacuum tube and non-return valve. The bottom of the header bottle has a 3/4” hose connection which runs to the water pump suction. The firewall is additionally cluttered with the normal 3/4” heater hose, a couple of wire looms (non-stock), bonnet release cable, speedometer cable and a flexible clutch hydraulic line. I may be able to move the bonnet release cable to a bent retainer attached to a cam cover nut.

Have also attached an archived photo that shows the Plus 2 firewall with the curved profile I need to consider.

Thanks

Stu

[mbell]

Standard heater hoses are 5/8" I'd with connections on the engine being 1/2" for some reason...

Could be a diy to buy some 5/8" Ali pipe and bend as needed.

[stugilmour]

Yes, I was thinking aluminum tubing as well. If memory serves I think my Esprit had aluminum tubes down the tunnel.

What grade and wall thickness would be appropriate? I saw on this web site that they recommend HPS 6061 T6 for their cooling system components. Not sure what wall thickness so it can be bent it flared to connect to heater hose. Unfortunately they don’t carry small diameter tubing.

https://www.racereadyproducts.com/alumi ... um-tubing/

Thinking I can source something appropriate locally if I know what to ask for. Any advise on bending and flaring appreciated. Not sure my flaring tool is big enough but sure I can have something made up, again if I know what can be done. Thinking a simple bubble flare on the tubing ends for attachment to heater hose with clamps. Have read the tubing may be able to be bent 90 degrees to about 3” radius, which might just work for a couple of bends.

Does this sound possible?

A bit of extra reading tonight and think the slight bend for the firewall may be accomplished by filling the tube with sand and easing a broad double bend over a padded knee. If that sounds reasonable I could perhaps try it on a scrap piece first.

Other material I was thinking of would be conventional copper pipe and solder on elbows and perhaps barbs? Or can a bubble flare be put in copper so a hose would be secure with a clamp? Is this appropriate for a cooling system? Somehow seems an odd choice.

Interesting that the Metal Mart guy was thinking stainless, which seems somewhat excessive and heavy.

Thanks for any thoughts. Trying to not sound like a complete idiot at the Metal Mart.

Any ideas on the stock speedometer cable?

Also forgot my choke cable is in the firewall as well. That will shortly be moved behind the dash where it should have gone.

Stu

[stugilmour]

And this just in. This article recommends against 6061 T-6 for bending and forming. Very interesting. Would probably be OK if I use straight pipe runs though.

https://www.thefabricator.com/thefabric ... 6-aluminum

Stu

[UAB807F]

(part quote)
A bit of extra reading tonight and think the slight bend for the firewall may be accomplished by filling the tube with sand and easing a broad double bend over a padded knee. If that sounds reasonable I could perhaps try it on a scrap piece first.

Other material I was thinking of would be conventional copper pipe and solder on elbows and perhaps barbs? Or can a bubble flare be put in copper so a hose would be secure with a clamp? Is this appropriate for a cooling system? Somehow seems an odd choice.

Personally I've never had success bending with the sand filled tubes, I suspect I couldn't get it densely packed enough to stop the tube kinking, The only way I've managed is with either a proper tube bending mandrel for larger stuff or a smaller hand held former that you can use for brake lines and probably up to 6mm soft tubing.

For bending 1/2" tube I'd go with a spring inside the tube, like you do for bending domestic copper piping.

On copper pipe/elbows/etc, I took that route earlier this year when I had to replace the heater pipes on my Europa. That's 2 x 1/2" steel pipes tack welded into the chassis spine and going from the rear to the heater under the screen.

I used copper pipe and soldered elbows for tight 90deg bends and to make a good seal at either end I soldered on the "bulge" section from a pre-soldered fitting instead of trying to flare the pipe. Works well and you can't see it in practice.

The only downside I can see to copper is that anyone looking will think "hmm, DIY copper tubing" which you may or may not like.

[stugilmour]

………The only downside I can see to copper is that anyone looking will think "hmm, DIY copper tubing" which you may or may not like.

Excellent! Very encouraging. You nailed it, although I was imagining painting the copper. This might be the simplest solution.

Did some more reading on aluminum grades. It appears the commonly available 6061 will bend OK as long as it is annealed. This apparently results in a TO grade; apparently T ‘oh’ is correct, but often called T0 or T ‘zero’.

This supplier has 3/4” pre-bent 6061TO aluminum tubing. The pieces are annealed to make the 90 degree bends, so I think the legs could be shaped somewhat further away from the existing work hardened 90’s. Two 4” x 12” L shapes could handle the header tank run very neatly, and the centre line radius of the bends is remarkably tight at 2”. I could either have the two pieces welded together to form the ~24” firewall run with the required two 90 degree offset bends, or perhaps trim and bend the long legs and fasten them together with a short 3/4” hose section that would somewhat follow the centre firewall shape.

https://burnsstainless.com/collections/ ... s-aluminum

I should have mentioned that I already suffered a failure of this hose run. A badly shaped 90 degree bend contacted the oversized exhaust header, which is remarkably close to the fibreglass on a Plus 2. A solid pipe will fit way better here, and I can easily connect to the header tank nipple with a simple 90 degree molded 3/4” heater hose.

For the heater run I think I have found a nice combination of universal molded heater hose that will fit the bill. Continental Elite makes 1/2” and 5/8” L shaped molded hose that can be joined together with a very neat barbed reducer adapter. I am planning to incorporate a 90 degree manual shutoff valve. This will replace an inline valve that doesn’t fit on the firewall terribly well, but works great for summer driving. I used this stuff already, but didn’t get the correct ID hose for the thermostat housing nipple and didn’t know I could easily join two sizes together.

Looking at some of the archived engine bay pictures I think I can really improve the mounting of the vacuum hard line and non-return valve by changing the hose lengths a bit once the other stuff is out of the way.

Thanks for the help. Any other ideas welcome.

Stu

[Donels]

Completely understand what you’re doing and something I have considered. However, I think to make it look good is outside of diy capabilities. Bending aluminium is much more difficult than copper. I would suggest you draw exactly what you want and then get a local fabricator to make them. This is the approach I took with my last restoration (not strictly a Lotus) and got all of the cooling pipes made from aluminium tube with ferruled ends, then just joined with straight hose sections. It looked really good. I used a fabricator in Cannock called RADTEC Radiators, there must be someone with the capability close to you.

[stugilmour]

Thanks Donels. Excellent advice.

Now that I have a better idea of what I want for the solid tubing run I think I can check back with the Metal Mart guy. He said he could put me on to a local fabricator. Basically thinking one 3/4” ID run of about 36” total length and two offset 90’s with flared ends. Shouldn’t be to bad.

Stu

[snowyelan]

Any places near you that fab stainless for boat railings etc? They would have all of the equipment for bending thin wall tubing, welding, etc and probably have the material in their offcut bin.
Metal Supermarkets are horribly overpriced, here in Ontario.

[HCA]

If bending aluminium tube is a pig, which it is, then bending stainless is a hog.

Copper - using a bending tool - is the way to go and have it chromed. As for the ends, use compression rings from a compression fitting with a light sweat of solder and send the whole lot off to be chromed...