I recently replaced the spark plug wire holder on top of the valve cover on my 1989 300E. I fired it up and immediately noticed severe missing at all rpms. Looked under the hood a noticed a distinct clicking sound coming from the distributor. Took the cowling off and saw some arcing between the end of plug wire #6 and the distibutor cap itself! Could I have inadvertently broke the connection cap inside the plug wire? If not any suggestions? I have recently replaced the the cap, rotor, plugs etc. and was running great until this! Thank-you for responding!

A spark will always follow the path of least resistance to ground. Check the plug wires and ends with an ohm meter. If it's arcing you will find one that's "open". They should read about 1K Ohms. Usually, it's just an end that's gone bad or had the connector pulled lose from the wire.
Regards,
Randy D.

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W.R.Durrance
ASE Master Tech
Mercedes Tech 20 Years
68 250SE
68 SAAB 96 Ice Racer
69 300SEL 6.3
70 300SEL 3.5
81 300TDT

Another good old " Low Technology " method of finding an HT leak is to make a pot of coffee and wait until it gets dark.....

You then open the bonnet ( hood ) and with the engine running you will often see the spark jumping across the area of the break or high resistance. Normally this is better seen in high humidity, makes the spark easier to jump !

Just a thought !

Hi Andy,
Good point. I keep a squirt bottle of H2O
on my ignition bench to check secondary insulation. I little mist sprayed on the wires will make bad ones go nuts on the scope. A word of caution about low-tech spark testing...the later "E"-Core coils(small ones)should not be given an "impossible arc" to jump. The spark will find ground inside the coil core and cause an eventual failure.
I never saw many coil failures until the 560s came out with the squat coils on them.
Regards,
Randy D.

------------------
W.R.Durrance
ASE Master Tech
Mercedes Tech 20 Years
68 250SE
68 SAAB 96 Ice Racer
69 300SEL 6.3
70 300SEL 3.5
81 300TDT

......that's noted Randy thanks, I'll bear that in mind next time I am sitting on the driveway in the middle of the night looking for fireworks !

The fireworks have stopped! A new set of wires did the trick and thanks to all that responded!

The fireworks have stopped! A new set of wires did the trick and thanks to all that responded!