What causes gouging in the distributor cap?

[Andy348]

I just bought a new distributor cap maybe 100kms ago. I pulled it off and inspected it now that the HG blew and the contact points are very worn in, and certain ones have large gouges in them.

What can cause this? I can provide a picture if necessary. I'd very much like to avoid buying a new cap..

[jlevie]

Spark erosion is what causes the gouging and it is normal wear of the cap. Replacement of the distributor, cap and ignition wires is a scheduled maintenance item due every other timing belt change (100kmi or 160km). Plugs v-belts are due every timing belt change. That is also when the O2, water pump, radiator, expansion tank, cap, thermostat, fan clutch, and all cooling system hoses are due for replacement.

[Andy348]

Timing belt has been replaced less than 1000kms ago and will be replaced again, ignition wires have been inspected and replaced those that look damaged, water pump,thermostat, fan clutch, hoses, etc are all brand new.

Maybe I wasn't clear - the distributor cap has wear with less than 100 kilometres on it. I'd like to prevent buying another one for the M20 to eat it in another 100 kilometres.

Thanks

[dnguyen1963]

less than 100 km? Something is seriously wrong here. What kind of wear are we talking about? Pictures?

[jlevie]

Aged spark plug wires can cause more than normal spark erosion. As can bad plugs or the wrong plugs. While a damaged ignition wire is an obvious thing. The wires just age and need to be replaced every 100kmi/160km or 10 years.

[Andy348]

Here's a pic:



Plugs are new, they're the WRTC8+ or whatever they're called from PelicanParts. Looks like I'll be ordering new spark plug wires and a new distributor... rotor looks good so hopefully I can reuse it.

[LJ851]

Great shot! I definitely can tell you that is a distributor cap. For sure.

[jlevie]

I would not replace that distributor cap at this point. But new ignition wires and a set of NGK ZGR5A plugs would go in.

[rodpaine]

Here's some comments about rotor and cap wear, with some decent pictures of them.
-Rod

[Andy348]

Haha yeah not the greatest of pictures, I know. I will order some plug wires and I've got spare plugs ready to go in.

Thanks to all & Rod that link was very helpful.