Pre-emptive maintenance
For pre-emptive maintenance, classic MG’s are fairly basic cars and simple to maintain by today’s standards. The long term health of the car can be easily looked after on a day-to-day basis by:
- ensuring all the maintenance checks and lubrication specified in the manual is done.
- tracking down water ingress into the bodywork as soon as it becomes apparent.
- applying cavity wax to key areas of the bodywork.
MGB
Water ingress:
There are three areas to check in particular:
The drain for the air intake vent in front of the windscreen needs to be kept clear. The outlet is at the very bottom on the drivers side, and drains to a tube with a bulb on the end of it protruding into the transmission tunnel from the top. It’s a mucky job to clean this out, but worth it as when it blocks it’s the first step to rusting out the heater box, a very difficult thing to get at to repair!
Ensure the baffle plates at the back of the front wheel arches are sealing properly and not letting water past to the cavity behind. Build-up of water and damp road dirt behind here is what causes the sills to rust, starting from the top of the outer sill where it goes behind the front wing, then working down from there over a period of years.
The plates come with a rubber strip to seal between them and the front wing. However, this never seals 100% particularly where it goes over the join in the wing (it’s behind the stainless body moulding on the outside) so it is a good idea to apply a bead of sealer such as CRC Galvseal around here to ensure it’s properly watertight.   Make sure that the sealer goes right up the side and across the top of the baffle, and sealing where the baffle meets the body on the inside isn’t a bad idea either.
To do the job properly, it’s best to remove the baffle plate (including the top extension if you can) and clean all the surfaces to be sealed so the sealer gets a good grip and can do its job. This is also a good opportunity to clean out the inner wing cavity behind the baffle plate – release the front wing at the bottom by undoing the three screws, pull it out an inch or so and flush the whole area out with a high pressure hose.
Once it has dried, you could apply a cavity wax through this area to give better protection against damp – though hopefully there will be none by the time you have finished! The sealer won’t stick to the cavity wax, so mask off the area along where the edge of the baffle plate sits before applying the cavity wax.
The door has drain holes along the underneath, these should be kept clear.
Cavity wax:
Cavity wax is a product which provides a protective film which stops water getting at the steel underneath. For owner maintenance, it is usually applied via an aerosol can and comes in several grades.
For inaccessible cavities, use a light viscosity cavity wax with good tracking properties such as Dinitrol ML, and a 360 degree spray on the end of a longish tube (say about 2 feet). Insert the tube into an access hole (drill one if you need to) as far as you can and gradually withdraw while spraying.
For open areas such as inside the doors, us a more viscous wax such as Dinatrol 77B. However, you should apply ML in all the corners first so it can track right in to any nooks and crannies such as where the door skin is crimped over the door frame.
Areas which should have cavity wax applied include:
- Front inner wing cavity (see above)
- Sill cavities – outer and inner (the divider between the two is along the lip where the doors weather seal is fitted)
- Inside the doors
- Cabin air intake box (after cleaning it out as above)
- The underneath of the point of the fins on the rear wings. Use Dinatrol ML or equivalent here, as the join along the fin is complex and a place where rust frequently starts.
- Up behind the dashboard where the front wing is bolted to the bodywork. (A bit messy to do, remove floor mats first and have something to catch/soak up the run-off!)
