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Heater Control Cable - How is it routed?

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Mr Creosote Avatar
Mr Creosote Dennis C
Visalia, CA, USA   USA
1967 MG MGB
Hi All
I'm putting the heater back in my 67 MGB that was removed many years ago. I have all the pieces plus a new valve. What I'm not sure of is how/where the heater control cable is routed through the firewall to the valve. If someone can post a pic of their cable where it passes through the firewall would be much appreciated.

Cheers

Mr. C

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Attachments:
Heater Parts.jpg    31.3 KB
Heater Parts.jpg

mvheim Avatar
mvheim Silver Member Mark Heim
CA, USA   USA
1966 MG MGB "Uroboros"
Kind of directly below the heater motor (when installed), on the shelf above the passenger footwell (USA), near the firewall, are two round holes side by side. One is for the line to the temperature gauge. The other is for the cable to the heater valve. Here is a stripped engine compartment view showing the hole locations.



Max Heim
'66 MGB California Melee 2006 & 2014 (passed along to another enthusiast)
'66 MGB (just launched)



Edited 1 time(s). Last edit at 2019-02-08 07:26 PM by mvheim.


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IMG_9780.JPG    61.5 KB
IMG_9780.JPG

Mr Creosote Avatar
Mr Creosote Dennis C
Visalia, CA, USA   USA
1967 MG MGB
Thanks Max
At the moment I have the Capillary Tube for the temp and the oil pressure tube going through them. Humm.. So the capillary tube routes through somewhere else?

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Attachments:
Gromets.jpg    40.1 KB
Gromets.jpg

Mr Creosote Avatar
Mr Creosote Dennis C
Visalia, CA, USA   USA
1967 MG MGB
Your heater box looks nice Max. Where did you get the grommets for where the core tubes go through the box? Moss says NA for those.

mvheim Avatar
mvheim Silver Member Mark Heim
CA, USA   USA
1966 MG MGB "Uroboros"
The capillary is right (I misstyped and corrected myself). The oil line does this other weird thing that is hard to describe. I will try to take a picture of the assembled car. I just happened to have that partially built photo on my Mac. But if you actually run the control cable from the knob and try to make it reach the valve on the engine, it will be immediately obvious which hole it has to go through — it doesn't have enough slack to go through the wrong hole.



Max Heim
'66 MGB California Melee 2006 & 2014 (passed along to another enthusiast)
'66 MGB (just launched)

mvheim Avatar
mvheim Silver Member Mark Heim
CA, USA   USA
1966 MG MGB "Uroboros"
The inner hole is for the heater control. The outer one is for the capillary. The hard line for the oil pressure comes out the side of the footwell (you can see I didn't have the proper grommet here) then bends up and around to the backside of the bronze fitting, neatly looping around the heater cable.

I just did a quick sand, naval jelly and respray on my heater box. In the closeup you can see it still has some "texture". I think I just reused the grommets, after cleaning them and soaking them in SonofaGun. This car had been stored indoors for something like the last 30 years -- a lot of the rubber was quite usable, unlike my old red car, where parts like this were rock hard and cracked.

The capillary is supposed to run along the engine block, but it had so much extra length I ran it along the fender all the way to the radiator diaphragm -- it seemed better protected that way.



Max Heim
'66 MGB California Melee 2006 & 2014 (passed along to another enthusiast)
'66 MGB (just launched)


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IMG_1392.JPG    46.9 KB
IMG_1392.JPG

Mr Creosote Avatar
Mr Creosote Dennis C
Visalia, CA, USA   USA
1967 MG MGB
Okay.. It doubles back and down through this hole. Thanks. The project just got a little more complex.


Attachments:
Oil Tube hole.jpg    39.6 KB
Oil Tube hole.jpg

Mr Creosote Avatar
Mr Creosote Dennis C
Visalia, CA, USA   USA
1967 MG MGB
Amazing! A picture is worth a thousand words! This little bracket was in the can of heater parts. I was baffled as to where it goes. Now I know. Thanks Max.


Attachments:
Bracket.jpg    26.9 KB
Bracket.jpg

Mr Creosote Avatar
Mr Creosote Dennis C
Visalia, CA, USA   USA
1967 MG MGB
Sorta like this... Thanks.


Attachments:
oil line 1.jpg    41.9 KB
oil line 1.jpg

MRoadster Avatar
MRoadster Gold Member Jim Wulf
Doylestown, PA, USA   USA
1938 MG TA Tickford "The TA"
1963 Ford Thunderbird "The M Car"
1967 MG MGB MkI "The B"
Here's another couple of photos for reference showing all of the clamps in place and the heater cable entry.



https://www.mgexp.com/registry/TA2566
https://www.mgexp.com/registry/GHN3L108333


Attachments:
Wiring and Line Clamps.jpg    39.7 KB
Wiring and Line Clamps.jpg

MGB Engine_RR.jpg    53.9 KB
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tahoe36c Avatar
tahoe36c Paul Hruza
Panama City, FL, USA   USA
1969 MG MGC GT "Little Red Rocket..."
1972 MG MGB GT "Tiny Dancer"
2002 Harley-Davidson Dyna
Dennis,

I routed my oil pressure line as yours is shown in Post# 7. Why anyone would want to do a U-Turn and then curve down and then inside and then turn aft again is beyond me... I believe in more "direct" approach. Must be the aviation mechanic in me.

Less curves equals less stressing of the tube with all this spaghetti routing! My heater cable goes directly inside too, using the hole supposedly for the oil line.

mvheim Avatar
mvheim Silver Member Mark Heim
CA, USA   USA
1966 MG MGB "Uroboros"
On the contrary, the u-turn IS stress relief.



Max Heim
'66 MGB California Melee 2006 & 2014 (passed along to another enthusiast)
'66 MGB (just launched)

tahoe36c Avatar
tahoe36c Paul Hruza
Panama City, FL, USA   USA
1969 MG MGC GT "Little Red Rocket..."
1972 MG MGB GT "Tiny Dancer"
2002 Harley-Davidson Dyna
Really???

So stretching one side of a tube and compressing the other adds stress relief??? I'm not sure which alloys you are using but I want some!!

Please explain Mark. You've lost me. A guy who has worked 38 years in the hydraulics of aviation. All the hydraulic lines are run as straight as possible to save weight (of course) and with fatigue in mind....

Once metal is forged or cast any bending pretty much changes the original molecular state doesn't it? I cannot see how that provides any benefit....

mvheim Avatar
mvheim Silver Member Mark Heim
CA, USA   USA
1966 MG MGB "Uroboros"
Aviation experience not necessarily relevant. Bend provides strain relief. See building codes for electrical conduit for example. Not a major point either way — certainly no reason to overrule how the factory did it.



Max Heim
'66 MGB California Melee 2006 & 2014 (passed along to another enthusiast)
'66 MGB (just launched)

tahoe36c Avatar
tahoe36c Paul Hruza
Panama City, FL, USA   USA
1969 MG MGC GT "Little Red Rocket..."
1972 MG MGB GT "Tiny Dancer"
2002 Harley-Davidson Dyna
Mark,

I think we are way off course here... Or we are talking about a completely different subject altogether.

Aircraft hydraulic tubing is 100% relevant since the oil pressure flex line/hard line from the engine output port to the gauge is a form of hydraulic tubing. It carries a liquid under pressure. That makes it "hydraulics" no matter the fluid it carries. No, it is not 3000 psi (or more) like an aircraft, more of a maximum of 70 to 75 psi but pressure is pressure. Whenever you bend any form of metal object into any other shape, flat, tube, whatever; it changes the molecular arrangement. This is factual information, not speculation. Does it mean that bending it 90 degrees and leaving it as so will shorten the lifetime of the tube or create a dangerous situation? Not necessarily, but why introduce additional bends when they can be minimized? It is just common sense...

Building codes for electrical conduit? Are you serious? Electrical conduit is simply a hard shielding for wiring that carries electricity... How in God's name does that have anything to do with hydraulic tubing that carries fluid under pressure????

Like I said previously; please explain. I am all ears... Or should I say eyes in this case! smileys with beer

Here is an engineering quote from the fourth paragraph of the "Stress-Strain Curve as explained in Wikipedia.

"Note that for engineering purposes we often assume the cross-section area of the material does not change during the whole deformation process. This is not true since the actual area will decrease while deforming due to elastic and plastic deformation."

https://en.wikipedia.org/wiki/Stress%E2%80%93strain_curve

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