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MG MGB Technical - Drain Tube replacement

Has any body found a easy way to replace the Drain Tube (from Vent Grill ) on a 1970 BGT(Moss part AHC321)without having to remove the gearbox? As usual the tube had filled with water,dirt and muck over the years then dried and hardened. When I tried to clean out the crud it seperated from the upper tube and there is not enough room for me to get my hand anywhere to replace it.Any solutions would be very much appreciated. Peter
p j mayo

this is a picture through the right hand heater vent. You can see the drain tube (Tom's knob) and the clip holding it.

Hope this helps

DK McNeill

PJ, you need to get a big screw driver onto the top of the pipe, when you have undone the screw, and lever it down. The rubber pipe will have grown onto the metal pipe.
you could also try a hot air gun to soften the pipe.

Colin Parkinson

Thanks DK for your input and the photo,not sure if I can get my big hands into that small gap but I'll give it a try. Also Colin, not sure if I explained the problem properly. I got the pipe off and it dropped down so that its resting on the gearbox but can't see any way to put it back where it should be! Ive tried pulling it downwards but the clip is preventing its exit!! and I can't see how I can push it back up in such a restricted space I can't help wondering why they didn't put a one long tube on that was removable from under the grill vent in the first place.Time to crawl back in the footwell I suppose. Thanks Guys.
p j mayo

You need one of those tools that look like a choke cable with a push button on one end and 4 tangs that expand and contract when the button is actuated. They're great for retrieving items that have fallen out of normal reach. They're inexpensive as well. RAY
rjm RAY

If you look behind the centre console and find where the demister pipes come through a steel plate. This plate is only held by self tappers and when removed it is possible to get ones hand into replace the drain pipe, Best done from the passenger side. easier if you can get someone to help by feeding the pipe from the gearbox tunnel whilst you position the rubber pipe back on to the plenum drain pipe. Jim
jim soutar

cheers ray, I do have one of those retrieval tools, one of the best bits of kit you can have in you garage,and has breen used many times,but in my case its not being able to put the thing back on once I have managed to retrieve it. Thanks also to Jim for your advice, the problem is I know the plate your talking about, I saw it where relacing the heater and demister tubes but unfortunately when they were dishing hands out I must have gone round twice as they seem a bit large to get thro that small but sharp aperture. I just wish they had put a much longer tube on that could be serviced from the vent on top, but then perhaps they wouldn't be so much FUN!! THANKS GUYS, Peter
p j mayo

eventually managed to remove the dreaded( Tom's Knob)but because of the restricted space and my large hands I found it easier after loosening the clip and lowering the pipe to use my angle grinder and remove a small section of the side panel wide enough to grasp the pipe,lift it and cut it in half removing the top half,(and you were right Colin it had grown onto to metal plenum) and allowing the lower portion to drop to the floor.It was so solid with dirt you would think it was full of concrete and the pipe was so inflexible.I Decided to put a straight through piece of pipe back, allowing any water and residue to fall right through and not block up again. The one drawback is the difficulty in finding a rubber hose 22mm inside dia to fit the plenum with 25mm outside dia to go through the re-enforcing plate, I have tried all the motor factors I can find and quite a few hose makers so far no luck but they say patience is a virtue. Any suggestions? 22mm i/dia 25mm o/dia 30mm in length,could be rubber or plastic. Peter
p j mayo

Lots of pipe sellers on ebay. I bet you can find what you want there with a bit of patience.
Mike Howlett

A midget 1275 top hose can replace Tom's knob and is a perfect fit..
K Harris

Metro's used the same part in the engine compartment, don't know about the size though. It prevents fumes being directed through the ventilation system. Mine was blocked on the roadster, which the PO kept outside. Rodded it through with a length of 1/4" dowel.
Paul Hunt 2010

This thread was discussed between 27/02/2010 and 31/03/2010

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