Here's Mud in Your Dust Valve Have you ever heard the old joke aboutgetting mud in your dust valve? Well, it canhappen on any MGB!
If your floor mysteriously gets wet aftera rain or after a trip through the car washand you can t seem to locate the leak, it isprobably due to the fact that the draintube/dust valve (Moss #363-171, page 67of the MGB catalog) is plugged.
The reason that this drain tube getsplugged is that the alr intake grllle at thebase of the windshield has holes in it largeenough to let in small critters bugs of allsizes, leaves, dust, or anythlng else thatcan get airborne. Mix these things with alittle water and it quickly seals off the verysmall opening at the end of the tube. Whenthis happens, the well at the base of the airintake will fill with water and overflowthrough the fresh air opening behind thecenter console onto the transmission tun-nel and down to the floors. All without youever seeing it!
To clean out the obstructions you mustremove the drain tube and clean it out.The clamp for this tube is loosened throughan access hole just aft to the heater open-ing in the right-hand side footwell. Youmust also clean out the metal drain at thebottom of the air intake. There is no easyway to do this, but the least painful methodis to remove the defroster tubes from thebase of the heater and run a wire up throughthe metal tube until it is cleaned out. Youwill have to remove the defroster tubes toreplace the clamp on the drain tube, so don't feel to bad about this; it beatsremoving the heater!
Note: If your car has never been re-stored or if you have had this leakingproblem for some time, you should re-move the heater and inspect the area be-neath it for rust.
After you have cleaned everything and replaced all of the tubes, you can then stop any more infiltration of unwanted matter by attaching a piece of door screen to the underside of the air intake grllle. Paint it black before you put it in and it will look like it belongs there. If you use the original style blind speed nuts (Moss #326-665)reinstallation even with the screen is a snap.
You may also want to remove the bulb at the end of the drain tube so that what goes in can get out. The opening from the factory is only a 1/16" slit!
This may help save a few more MGBsfrom rotting away.
Bill BusslerMuncy, PA
Working on automobiles is inherently dangerous. Moss Motors, Ltd. is not liable for injury or damage due to incorrect installation or use of their products. All products are sold with the understanding that the safe and proper installation and use of the products is the customer’s responsibility. Follow factory workshop manual procedures and instructions, but use current shop safety standards and common sense. Some tasks will require professional advice or services which Moss Motors cannot provide.If you have a specific comment or question and you'd like an immediate reply from Moss Tech Services, don't post here - please first email: BritishTechnicalSupport@mossmotors.com Please include the Title and Location of this tip if applicable.
Forum
FAQs here.