Technical Bulletin 049801, dated 4/98

Ford Probe GT
Mazda MX3, MX6, Xedos, 323, 626
Eunos 30X, 500
(with Mazda 1.8, 2.0 and 2.5 litre 24 valve DOHC V6 engines)

These engines suffer badly from oil leakage problems which, in turn, will affect spark plug wire reliability and performance.

As these engines get older, they suffer more than most from oil leaking from the cam cover gaskets. The leaking oil collects in the bottom of the deep spark plug wells and around and over the bottom of the spark plug connectors attached to the ignition wires. Oil accumulating in the spark plug wells will cause two problems:

Firstly: Prolonged immersion in hot oil will cause the silicone rubber seals attached to the bottom of the spark plug connectors (by RTV Silicone adhesive) to swell and un-glue themselves from the plastic tubes, causing the bottom connector seals to remain on the spark plugs when the spark plug wires are removed from the spark plugs. The silicone rubber seals are needed on each wire to provide a complete seal around the spark plug's porcelain insulators.

Secondly: old engine oil can be slightly conductive, as it contains carbon and other contaminates caused by combustion. Conductive oil can cause sparks to track (inside the connector) from the metal spark plug top down the outside of the spark plug's porcelain insulator to ground out through and around any swollen oil contaminated bottom connector seal. This problem is exacerbated by the spark finding it easier to track down the outside of any spark plug saturated with conductive oil in preference to firing across the spark plug gap — particularly if extra voltage is being used to fire spark plug gaps that are excessively eroded (or adjusted wider). Magnecor wires can sometimes make the tracking-to-ground problem worse if the connector is not correctly connected, since more spark energy (compared to factory carbon resistance wires) flows through Magnecor wires.

If the seals come off your spark plug connectors, we suggest the following:

Replace the silicone rubber seals: The plastic tubes, including inside around the metal terminal, must be completely free of any oil (use a solvent — but do not soak) and when clean and dry, attach new silicone rubber seals (available from Magnecor) with RTV silicone adhesive. Magnecor can do this for you, for a small charge, if you return the wire/s (we will clean the wire/s). NEVER re-use an old seal!
Clean out the oil from around the spark plugs: This may not be easy, particularly if the oil has leaked around and over the rear spark plugs — but it must be removed from the holes before the wires are re-fitted. A suitable solvent should be used, and the dissolved oil and solvent should be removed, preferably with compressed air (wear eye protection). Never start the motor until all of a solvent based cleaner is completely evaporated — and never remove spark plugs until the wells are clean and clear of any debris which could fall into cylinders and pass through the engine into the catalytic converter.
Repair the oil leak/s: Usually this entails replacement of all cam cover gaskets, but sometimes it may be possible to carefully and evenly tighten the cam cover bolts — although you should NEVER tighten any cam cover bolts beyond the specific torque recommended for this engine (ask a Mazda dealer for this information, or get the job done by a skilled technician) since over-tightening the cam cover bolts will cause other problems, including crushing and damaging the gasket, and possible damage to the cam covers themselves. Replacement of the gaskets requires removal of other components (the throttle body to access the rear cam cover in particular), therefore we recommend you not attempt replacing the gaskets yourself unless you have successfully performed similar work beforehand.

You should regularly (at least once a year — more often on high mileage cars) check for the presence of accumulated oil in all spark plug wells.

Magnecor, like other wire manufacturers, does not take responsibility for problems caused by engine design, inadequate engine servicing or incorrect fitting of wires. However, if your Magnecor wires are damaged by oil contamination problems, we can usually repair wires sent to us.

With proper attention, a set of Magnecor wires correctly fitted should never wear out on this engine, as long as engine oil and water is kept off the connectors in the spark plug wells.

Please call your dealer, or Magnecor, if you have any questions.
Please feel free to
contact Magnecor if you have any feedback, we are always interested in your comments.

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