the_hairy_baboon
Active member
- Joined
- Dec 1, 2021
I have a 1990 Haynes manual for 240 model Volvos and there's a very odd piece of troubleshooting they have in the ignition section
All spark plug wires (or COPs) have a large boot to prevent arcing to anything that's not the spark plug. Therefore the end of the spark plug lead shouldn't be able to arc to the engine body.
The online link for checking spark plugs at haynes.com says to either use a tester OR pull the lead off, remove the spark plug from the engine body, reconnect to the lead, and then hold close to the engine body to check for spark.
Why would they initially suggest a method that wouldn't work? Was it because the original spark plug wires just used vast distances to prevent arcing and therefore didn't need a boot? Everything I can see shows stuff with boots AND even with a metal body outside the rubber interior boot there's still not arcing.
3 If the engine still fails to start, check that the current is reaching the plugs, by disconnecting each plug lead in turn at the spark plug end, and hold the end of the cable about 3/16th inch (5mm) away from the cylinder block. Spin the engine on the starter motor
All spark plug wires (or COPs) have a large boot to prevent arcing to anything that's not the spark plug. Therefore the end of the spark plug lead shouldn't be able to arc to the engine body.
The online link for checking spark plugs at haynes.com says to either use a tester OR pull the lead off, remove the spark plug from the engine body, reconnect to the lead, and then hold close to the engine body to check for spark.
Why would they initially suggest a method that wouldn't work? Was it because the original spark plug wires just used vast distances to prevent arcing and therefore didn't need a boot? Everything I can see shows stuff with boots AND even with a metal body outside the rubber interior boot there's still not arcing.