Postby jondee86 » Sun Dec 23, 2018 8:36 pm
Based on the fact that you only have a problem in cold/wet weather, and that
heating the engine got it going again, I think that for sure moisture is messing
with your electrics. So how does it do that ??
Water is a pretty good conductor of electricity, and a thin film of water on the
outside of a coil or distributor cap can make a good ground path for high voltage.
A good working coil can put out anywhere from 25 to 40,000 volts. Normally that
voltage gets to ground by first jumping rotor to cap gap and then by jumping the
sparkplug gap. There is also plug wire resistance to overcome.
High voltage is always looking for an easy route to ground... it will literally take
the path of least resistance. The rubber caps that cover the sparkplugs and the
ends of the wires that connect to the distributor cap and coil are there for a reson.
If they are old, perished, cracked or loose, moisture can create a path to ground
that has less resistance that going to ground by jumping the spark plug gap.
The high voltage can track to ground on the outside of the spark plug porcelain,
on the inside of the distributor cap, on the outside of the cap or on the outside
of the coil. Once this starts to occur the spark begins to form a track on the
surface from ionised carbon particles, and that track will allow the spark to short
to ground even when the surface is dry. If you run your engine at night with the
hood up, you can often see a blue spark where the high voltage jumps to ground.
So, what to do ?? Here is my suggested list...
1. Remove the distributor cap and wires... pull the wires out of the cap.
2. Using carb cleaner or similar, thoroughly clean both the inside and outside of
the cap. Clean inside the sockets for the wires. Check inside and outside for a
thin black trail that might run from one of the pins to the bottom edge of the
cap. If you find any of these, your cap is pretty much done for as the carbon track
is almost impossible to remove. If no tracks then...
3. Using whatever works for you, clean any oxide "fuzz" off the edges of the
metal pins inside the cap.
4. Do the same to the brass tip on the rotor. You want clean, sharp edges. Remove
any oxidation from the spot on the rotor where the carbon button rubs. Make sure
you still have a carbon button and that it is free to move.
5. Clean the outside of the plug wires and check for any signs of cracking or shorting
from the wire to ground. Clean and dry inside the rubber caps also.
6. Clean the outside of the coil and look for tracking. Clean and dry inside the
socket for the high tension lead. Clean the lead as above.
7. If you are high tech, check the end to end resistance of the plug wires. As a rough
guide you are looking for about 1kOhm (1000 Ohms) per inch.
8. Look to see if there is water/oil/dust collected around the spark plugs. Clean
that out before removing the plugs for inspection. If the spark end is OK then clean
the porcelain and reinstall.
9. Reassemble the distributor cap and install. Use a thin smear of dielectric grease
inside each rubber cap. Dielectric grease does not conduct electricity so you do not
want it to get between any of the metal parts that are supposed to be conducting
electricity. Just a smear to prevent the caps from sticking and help keep moisture out.
In an emergency, the use of a water-displacing spray such as WD-40 on the outside
of of the distributor and coil can help start a system that has been killed by water
splashing under the hood.
Happy holidays.... cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.
