Technical Bulletin 019701, dated 1/97, revised 11/97

Ford Escort GT
Mazda MX3, MX5 Miata, Protege, 323
Mercury Capri, Tracer LTS
and other cars ...
(Mazda 1.6 and 1.8 liter 16 valve DOHC engines)

We have recently identified some problem areas of the above engines, in regards to poor design of the factory spark plug wire connectors and valve cover assemblies, as well as spark plug wire fitting problems. In our opinion, this problem is so serious, that many of the driveablility and spark plug wire problems that owners encounter, including hesitation and misses, can be directly attributed to the hostile environment in which the wires operate, and specifically to moisture accumulating in the deep un-drained spark plug holes.

We have found that these engines are all prone to moisture accumulating over spark plugs and the bottom of the spark plug connectors attached to the ignition wires. This problem is possibly caused by the design of the valve covers, which do not keep moisture out, and the design of the factory spark plug connectors that do not provide sufficient sealing although, because the connector top seals are vented, better sealing may not help in areas (usually by the sea) where heavy condensation forms during the cooling down process over engines and inside covered spark plug holes.

The presence of moisture causes sparks to track (inside the connector) from the metal spark plug top, down the outside of the spark plug's porcelain insulator (under the connector's bottom seal) to eventually ground out into the moisture. This problem is exacerbated by the spark finding it easier to track down the outside of a wet spark plug in preference to firing the spark plug gap usually because of an excessive (or worn) spark plug gap, failing spark plug or high chamber combustion pressures. Magnecor wires can sometimes make this problem worse if the connector is not correctly connected, since more spark energy (compared to factory carbon resistance wires) flows through Magnecor wires.

Once moisture accumulates, it remains around the spark plugs (it can’t drain away), as generally, the engine's temperature will not entirely evaporate the water because the same vented connector top seal that was ineffective in keeping water and moisture in the air out, is very effective in preventing evaporation of the moisture inside. The problem is further exacerbated if oil is leaking from valve covers and mixing with the moisture (another problem with older cars).

The problem is mostly noticed by the engine hesitating or missing when under load (particularly at low speeds), and is usually not apparent immediately after new wires are fitted. The usual diagnosis by unknowledgeable dealers and/or technicians is: "bad wires." The usual remedy is to replace the wires with a new set, which solves the problem if the wires are fitted correctly, although the remedy is only temporary if wires are again not fitted correctly and the moisture is not removed from the spark plug tunnels, or again accumulates around the spark plugs.

A moisture accumulation problem can be temporarily solved by simply applying silicone grease to the inside of the spark plug connectors' bottom seals, and replacing the seals if car has been driven for some time with the problem occurring, or at worst, replacing the individual wire if there is evidence of arcing (white marks) around the bottom seal. Apart from correct fitting, future problems can be reduced by applying silicone grease to the inside of the bottom seals (or preferably directly to the outside of the spark plug insulators themselves) at regular intervals. However, take into account the silicone grease will eventually run out of the seals down the hot spark plug insulators. To reduce the number of moisture accumulation occurrences, all water and oil should be removed from inside the spark plug holes and especially from around the spark plugs themselves whenever ignition wires are removed.

We recommend inspection of wires for moisture and oil at least once a year (preferably before winter), or more often. Sometimes moisture can be seen as a yellow or white discoloring of the spark plug connector bottom seal which fits over the spark plug (see photograph, below). However, evidence of moisture is not always obvious to the untrained eye therefore we recommend that owners accept that moisture will inevitably accumulate from time to time more so if you drive in rainy or humid areas, or live near the sea where heavy condensation forms over the engine (usually at night as the engine cools down). The presence of oil will be obvious, and should be cleaned off connectors before any silicone grease is added.

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 incorrect fitting and moisture accumulation problems, we can usually repair wires sent to us. Magnecor has made efforts to redesign the wires to help overcome these problems, and redesigned wires are now being sold to our customers.

With proper attention a set of Magnecor wires should never wear out on this engine, as long as the preceding procedures are followed.

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.

Evidence of moisture accumulation will sometimes be seen at bottom of spark plug connectors as rusty colored or white sediment left on the connectors. This example (above) of a wire from a Mazda shows rusty colored sediments.

Spark plug hole (below) shows evidence of sediment (will also be evident at bottom of hole). With original connectors removed, moisture can often be seen on spark plug porcelain if a light is shined down the hole.

Click here for another photograph of a problem wire (from a Ford Taurus SHO) showing white sediments, and also demonstrating oil leakage.

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