Mark Edgley wrote:
>
> So I have this Honda, US car, 352K miles, 1300cc engine, and for the
> last few years the thing has been eating a distributor cap and rotor
> once a year or so. The symptoms are very odd. The inside of the cap
> is always kind of oily damp with a really sharp acid smell, the
> aluminum contacts inside the cap are always really corroded with a
> fluffy white oxide, and the carbon contact button that connects the
> coil wire to the center of the rotor is eaten away nearly flat and
> fused with the cap. The metal bits of the part that holds the
> magnetic pickup are very rusty. And yet the thing starts and runs
> amazingly well. Every so often I get in there and clean the cap,
> scrape the contacts clean, etc. Eventually it will get to where it
> runs too rough that I have to replace the cap and rotor, and then we
> start all over.
>
> Anybody have any idea what's going on here? The only thing that
> occurs to me is that I recently had to have the head gasket replaced.
> Is it possible that when the old gasket went bad, it was leaking steam
> past seals or something and into the distributor housing from below?
> If not that, then what the heck?
>
> I'm hoping to make half a million miles on this beast, if it will
> last.
>

I don't have a direct answer to your question but here are some things to
check....

There should be a rubber gasket that goes between the distributor cap and
the distributor body. If this gasket is missing, broken, or dried up and
brittle then moisture can get into the distributor and could be causing some
of the corrosion symptoms you're experiencing.

The "oily damp" symptom could be caused by a bad oil seal in the
distributor. If this is the case, then you may be best off going with a
used distributor as, to the best of my knowledge, the seals aren't available
from either the dealer or the aftermarket.

Check the vacuum advance. This should hold vacuum. If not, then your car's
timing will not be correct.

Check the advance plate. When you pull vacuum on the vacuum advance (as
long as it's not leaking) you should see the advance plate turn a given
amount (I don't have exact specs for this but it's roughly 10° or so). With
as much corrosion as you're describing, I would be willing to bet that your
advance plate may be frozen. Even if it's not frozen, the bearing retainer
in the advance plate often breaks. This causes the advance plate to sit
crooked resulting in unequal or nonexistent air gaps with the reluctor.
Sometimes you can find the steel bearings stuck to the magnet when the
advance plate goes south.

Check the magnet. You'll need a small mirror and a flashlight for this
one. If it's cracked or broken then it needs to be replaced.

It's also important to check the mechanical advance. You should be able to
turn the distributor rotor 10° or so and then have it spring back. If this
doesn't happen, then the distributor will need to be disassembled so that
the mechanical advance can be cleaned and lubed. Note that the top shaft in
the distributor can go on in either of two orientations however only one is
correct. Make some hash marks on it with a carbide scribe indicating it's
orientation such that you can get it back together correctly. If you get it
wrong, you won't be able to time the car and will need to take things back
apart.

This diagram should help to give you some idea of how all the components are
stacked together, http://tinyurl.com/3tlr8. It's for an Hitachi distributor
from an '85 1300 49 state 5spd. The other possibility is that you could
have a Tek distributor. If that's the case or the diagram is not correct,
then put the correct info for your car into this page
http://tinyurl.com/6yprt.

Eric