Piggy-back condenser to check if the fitted condenser is faulty

Ian Ailes (MGBGTV8 Glacier White 1561) co-manages the Fairmile Natter just west of Esher in Surrey. Here he provides a useful way of checking whether a condenser is faulty.

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Spare condenser fitted with crocodile clips
Ian Ailes says "the spare condensor can easily be clipped to a nearby earth and the wire between the coil and distributor to check if the fitted condenser is faulty. If it is faulty the piggy-back condenser will override it and the engine start firing properly. Rally cars before electronic ignition would have one bolted to the inner wheelarch with and extended wire which can me clipped to the coil if the fitted distributor condenser failed. With the high failure rate of condensers, everyone should keep a spare one in the glovebox. The condenser is not polarity sensitive so will work on older positive earth cars as well. It's probably worth extending the tail wire to make it easier to fit". See photos

"Apart from a faulty condenser, other problems I have come across recently which manifest the same fault are:
o Loose screw holding the condenser in the distributor causing an intermittent earth
o Internally broken tail wire due to fatigue or pinching - not visible and not always obvious
o Wire inside condenser is shorting out on the body - the sleeving can melt and short out. A piggy back condenser won’t work due to the short. Check the tail wire is not touching any metal inside your distributor.

All simple faults but a nuisance to diagnose.

I buy Intermotor condensers which the trade seems to rate well. Running a natter, I get asked a lot of questions about faults – often a batch of the same. Its quite rewarding to find the answer and pass it on to other members". See Ian's article with a useful guide on "how to test a condenser". Link