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MG MGB Technical - Toms knob dropped!

Sounds painful! driving the other day I noticed a clonking when going over a bump coming from near my left knee (RHD 70 Roadster so sprung flaps on heated outlets) looking under the bonnet revealed 'Toms' hanging down and knocking against the tunnel. Now it appears to still have the clamp at the top as it will not come out downwards so having read http://www.mgb-stuff.org.uk/drain.htm#4 I thought easy just re secure it. BUT and its a big BUT there is no hole near the vent nor any evidence of there ever being one! so HOW pray tell do I get to the top of the tube to reconnect it. Is it possible without the hole? I am loath to go drilling new access but currently I either strap the pipe to the body to stop the knock or get rid. but catch 22 I can't remove the top clamp to remove it (No access!) and there are not many options for tying it up. Any thoughts?
TIA
Bernie
B Anderson

I'd be surprised if that access hole only appeared between 1970 and 1973, but anything is possible. You do need to do something about it otherwise any water going into the vent will lie in the double-skinned section above the tunnel and either rot it out or leak into the cabin. The fact that it has fallen off anyway may indicate that the spigot it normally clamps to has rotted off. The cut-away indicates that by removing the screen air vent pipes from behind the console, and the plastic tubes that run forwards to the heater box, you may be able to see the spigot from the air box and the top of Tom's Knob (ooer Missus). May even be able to reattach it that way (perhaps that is how they were done before the footwell hole and blanking plug was provided).
PaulH Solihull

I guess some more handstands in the foot well are in order then. luckily it does not come out in the rain (Said the bishop to the actress :) (The car that is ooer missus indeed). I found this earlier http://www.mgexperience.net/phorum/read.php?1,1959473,page=1
that seems to indicate that it is accessible from the vent - fingers crossed. I refuse to take the heater and box out! If I can't get to it I'll have to live with it

Bernie
B Anderson

Bernie,

I did this job once but with the heater removed. Paul's suggested method rings a bell. What I do remember is that the job was a 17 band-aid one. Every edge, from the console edge and the heater tube access plate lip inward seemed to have nasty 'little' cutter points on them. I'd suggest sleeves and gloves and try to avoid the arm straining onto any of the edges. Where unavoidable try not to draw the arm across the edge (just prepare to grimace as contact is made).

I got it done. The spigot on mine had rusted but retained the bilk of its structure. I think I used a hose clamp to reattach the tube. IIRC the spigot 'hangs' from the 'roof' of the space containing the heater flap section. If that is right it is going to be a tight reach with the heater in place.

Problem is that Paul is correct in that without a drain tune to the exterior, the plenum chamber will drain directly into the double-skinned section with the results mentioned.

May not be a lot of fun but probably worth doing!

Regards
Roger
Roger T

This is where it is on my '67 - just inside the footwell flap.

The newspaper is what I've stuffed into the plenum while cleaning the engine bay.

Dave O'Neill2

Thanks for the pic Dave. Looks like the flap is larger than the 'covers' hence the access hole on cars with those as opposed to springy flaps. I might be able to get in after all (Fingers crossed)

Bernie
B Anderson

I've just been out to check my 1969 car. The heater outlet with opening flap is wider than the type shown in Paul's photo and so you can see the top of the tube through the outlet. There is no need for an access hole and no room for one either. In theory you access the clamp through there, and I did, but it involves considerable gymnastic ability.
Mike Howlett

Having now looked at the pictures on paul's website, I can see why it would be difficult to fit the cable to the heater flap after the heater has been installed.

When removing my heater, I disconnected the cable through the hole in the footwell and wondered what all the fuss was about. Now I know.
Dave O'Neill2

Very good picture Dave, I'd like to add that to my site if I may.
PaulH Solihull

Yes, certainly.

Or would you like a clearer one without the clutter?

I've just found some more that I took during the dismantling process.
Dave O'Neill2

The two you have sent are great, thanks.
PaulH Solihull

Had a good dig around (literally!) today managed to get at the spigot only to find that it is almost flush with the bottom of the chamber. I did manage to get a large amount of dry mud out with a bit of a struggle but I can now see light from the top so at least the way is clear for any water to get into the lower section! I might see if I can get some sort of flanged plastic pipe and stick it to the bottom of the box but for now I'll live with it and keep an eye out for damp. BTW it really is a sod to get at but with the vent cover off and the seat right back it is possible to see in there.
Bernie
B Anderson

Reminder to anyone needing a replacement tube.

If you want to preserve original appearance and functionality, find a wrecker/scrap yard with Austin 1800s. They have two drain tubes in the engine bay. The only difference is they had an elbow joint at the top but this can easily be cut off.

John
John Minchin

This thread was discussed between 09/05/2012 and 13/05/2012

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