MASCOT January-February 1997

THE ROADSTER FRONT - Hole Hunting

Bill Haverly

When things go wrong, sometimes it's little items on a car that cause as much trouble as the larger components. Little holes, for instance, can be a hundred times more important than their size would suggest, and give numerous problems if left unattended. An example of the table salt cellar when its outlets get blocked puts it in a nutshell. This little hole is the most fundamental part of the operation.

As to the Roadsters little holes under scrutiny, all have the same thing in common - the need to be kept clear. Otherwise they could cause problems in starting, running or braking.

For a guided tour of these pinholes lets start at the rear where the petrol filler cap presents a classic case. All petrol tanks need venting to prevent vapour lock occurring, most Roadsters have a small hole in the cap centre to enable air to enter as the tank level drops. With a blocked hole, the pump will eventually be unable to deliver, as a developing vacuum prevent the flow of fuel. Some Roadsters may have an internally vented cap in which a hole on the underside breathes out under the rim. But the principal is the same, and the need to keep it clear to avoid fuel starvation.

Further down below on the axle casing top are two other slightly bigger holes around twelve inches from the flange at either end. Their purpose are as breather holes for the axle, preventing pressure build up which could force oil past the oil seal on its way to foul up the brake linings. That's the theory anyway, and blocked holes could be the reason why the Roadster axle oil seal has such a tarnished reputation.
Much scraping away of old paint or grunge is often necessary to locate them and something like a hatpin is a useful tool for the clean out.

Whilst in this area, the brake drums are well worth a visit. There are four more little holes in each drum, set equally in the four corners of the drum recess. Once again, some poking around might be necessary to find them, for in 9 out of 10 cases brake lining dust will have clogged them up. Designed to let water out under pressure when wet weather conditions could severely affect the braking, a clear out around every 10,000 miles is a reasonable interval for attention. Check also the same holes in the front brake drums.

The Solex 30 FAI carb fitted to Roadsters from the 4A-on is generally a reliable and trouble free unit, but can have problems forced upon it by a dirty petrol tank. You stop at traffic lights and the engine dies. The car starts and runs ok if you keep the revs up, until the next stop, then dies again. It will not tick over without increasing the revs. It's an odds on bet that the pilot jet on the carb's top left corner is blocked. The "get-you-home" solution is remove with a 2 A spanner and clear by blowing or with a fine fuse-type wire - the long-term answer is clean out the petrol tank or fit a concealed in line filter.

The last little hole to be investigated is the manifold drain pipe, which allows excessive petrol from the carb to drain away and prevent engine flooding and subsequent starting difficulties. Here, the common or domestic pin is the classic tool for clearing out the tapered end of this capillary tube. Every tool kit should have one!