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post #11 of (permalink) Old 13th December 2007
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I solved it with RTV sillicone glue and insulator tape..the pint sized hole is caused by moisture tru flashover...get sealing rings to prevent moisture leaking into the chamber and use BOSCH SUPER spark plugs to prevent spark plug flashover...cos it has corrugated ribs on its insulator.

This is savvy's connector, pic posted by nerdeliteonline ..I had a similar hole on my 4th connector though a little smaller where my 3rd and 4th plugs oxidised badly. Rough idling, engine misfirings and power loss happened right just after a heavy downpour. Solved with insulator tape and a new set of spark plugs.

My badly oxidised plugs.
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Check out the link
Magnecor Race Wires: Mitsubishi twin cam technical bulletin

Same problem found on other types of connectors! And at the same location!

Spark plug connector shown above has been damaged by water inside a spark plug well. Red arrow points to an arc-hole burnt by the spark arcing through the plastic tube to reach the water on the outside of the tube at times when the spark finds it easier to ground out to the water than it is to fire across a widened spark plug gap (from wear or adjustment) when the engine is under load.

An arc-hole in the plastic tube can be hard to find, and a magnifier will help (it is not always as obvious as the example shown at left) but usually it will appear at the location marked by the red arrow (anywhere around the plastic tube). The example connector shown also had oil all over it from a leaking valve cover gasket, and the car had been driven a great number of miles in this condition with the engine misfiring each time the connector became wet and arcing occurred.

Hot engine oil can also cause the bottom seal to swell.

Example of latest version all silicone rubber one piece spark plug connector shown above (also covered in engine oil) can withstand more abuse from water and oil than the OE style connector, although too much water and/or oil in spark plug well will also cause this style connector to become damaged over time. If water is not removed from well soon after an engine miss is first noticed, an arc-hole can also be burned by the spark wanting to ground out to the water on the outside of this connector in preference to firing across a widened spark plug gap (from wear or adjustment) when the engine is under load. Red arrow indicates area where an arc-hole will most likely be found (anywhere around the connector's shaft).

Spark Plug flashover

Spark jumping from terminal nut to plug shell - Spark Plug 411

Flashover is when the voltage sent to the spark plug does not fire between the center and ground electrodes within the combustion chamber, instead, it shorts between the metal shell and the terminal nut on the plug exterior causing the engine to misfire. This can occur when the air is highly ionized (such as on a stormy day), or when the insulator is dirty. To reduce flashover the top portions of the insulator have 4 or 5 ribbed corrugations(depending on manufacturer).

Wiki:By lengthening the surface between the high voltage terminal and the grounded metal case of the spark plug, the physical shape of the ribs functions to improve the electrical insulation and prevent electrical energy from leaking along the insulator surface from the terminal to the metal case. The disrupted and longer path makes the electricity encounter more resistance along the surface of the spark plug even in the presence of dirt and moisture.

*Note: our stock Champion spark plugs' insulator only have smooth surface compare to other compatible Bosch, NGK and even Denso.

LATEST UPDATE: ONLY Bosch spark plug has the corrugated feature while the stock Champion and NGK plugs have smooth surface insulator.

D4F sparkies:
Champion REA8MCL (stock)
Bosch Super VR8SEW (recommended)!
Denso FXE20HR11(SIP IRIDIUM Not Tough***65289;

Champion plugs


Not-for-savvy NGK plugs

Note the threaded part is shorter than ours, means Savvy's D4F engine head is very thick which is a good thing.

Bosch plugs

How to solve/repair the problem

1. wrap the connector's affected area (the hole) with insulator tape.
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2. Repair it with RTV silicone adhesive. Clean the connector with a solvent, and open up the hole with a small nail or paperclip so that the RTV can be pushed into and around it. Allow RTV to set for about 12 hours. Remove all water and oil from spark plug well before re-installing. Also check condition of spark plugs.

Magnecor Race Wires: Mitsubishi twin cam technical bulletin

How to prevent the problem from happening in future.

1. Seal with O-rings to prevent moisture/water going into the hole. Tobyboy's method.

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2. Reinforce the connectors with hi temperature insulator tape ( can be bought at Jusco at RM7 per roll. Wrap at lower part of the connectors, where the holes could possibly appear like shown in the pic. That's what I did to the unaffected connectors).

Another example of such tape.

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