Ignition System Question Points Burning

[Mal Leichter]

Hopefully this will be my last thread of the season. Now that I have gotten into maintaining my A4 I am finding out all sorts of good stuff.

The fuel system issue we were chasing ended up being severly burned points. Last week I replace the points and condenser and the engine is running GREAT. I chect the points yesterday after about 12 hours of motor time just to see what they look like. I expected them to look like brand new but they were alittle grey and smokey looking. Seems to me like that is a little soon to be showing anything but shinney and new.

I have 13.2 Volts with the key on and the engine off from the positive side of the coil to ground. I get the same reading from the breaker arm to ground. I next tested resistance. I got less than .3 ohms from the fixed side of the points to the breaker plate in the distributer and the same reading to a head bolt. Same readings for the condenser to ground.

The Coil was replace about 2 years ago when the boat yard was chasing a problem where the engine would just still like somebody turned the key off. The coil currently installed is a Merc-Cruiser 392-805570-1.

I'll be keeping a spare set of new points on the boat JUST IN Case but was wondering if anybody could point me in the right direction.

Thanks AGAIN!! I owe you guys!!!!

Mal Leichter
1979 Tartan 30 SKYE #585

[Don Moyer]

Mal,

I'm wondering if you might have a slight anomaly in your meter. It's rather unusual to read over 12.5 volts with the engine off (no alternator contribution to the DC system), and I don't think you should see any resistance between the fixed part of the points or the condenser and ground. Perhaps someone with better electrical background will weigh in.

Don

[Mal Leichter]

Whoops My poor typing skills are exposed. I measured 12.2 volts NOT 13.2.

You may be right about the meter though. It is a digital radio shack VOM meter. It sometimes reads several milli-ohms when it is connected to nothing and the numbers seem to change.

I have an old fashion magnetic meter that I will bring with me this weekend.

[Mal Leichter]

Points Burned again

Don

I replaced the points in my A4 in July. The engine started dying again yesterday (sounded like the key was turned off). I checked the points and they are all pitted and burned again. I bought a new set of points and condensor but seems to me they should last more than 10 weeks.

What causes points to burn???

The coil was replaced 2 years ago by the boatyard. Is it possible they put in the wrong coil? Could that cause it???

[marthur]

Pondering Pitted Points

The usual causes for pitted or burned points are setting the points too close or having a bad condenser.

I assume you have replaced both the condenser and the points, so double check the gap on the points. Or even better, use a dwell meter if you can find one.

Good luck!

ma

[Mal Leichter]

Points and condensor were changed at the same time. Points were set to .025. This is 2 sets of burned points and 2 condensors since early May

[marthur]

Your ignition points issue is very curious. Using a dwell meter will probably do nothing more than confirm your careful setting of the points.

I have two thoughts.

The first is to open the points a little. An old timer I was talking with a few years ago had the opinion that not every engine worked best with its points set to the the book value. I know that the manufactureres of other engines with breaker points often specified a range of values for this reason.

The second is to install an electronic ignition kit and be done with points forever.

Good luck,

Mike

[tenders]

> The coil was replaced 2 years ago by the boatyard. Is it possible
> they put in the wrong coil? Could that cause it???

Seems to me, wires and plugs aren't going to burn your points. Points can last hundreds of hours. It's either the coil or the alternator. I'd vote to have the alternator tested in a shop (easy, probably free) and swap out the coil...and if the points last a while, THEN replace them with electronic ignition.

I just installed electronic ignition this summer--it really makes a difference. But I wouldn't risk burning up a $100 part if something else is really wrong.

[Mal Leichter]

The alternator was changed this weekend with a new one from 55 Amp one from MM. I didn't know an alternator could burn points. Thr highest voltage I ever saw the old one pit out was 13.1 volts. Not sure of the amperage because the amp meter never read anything. Need to repace the wiring to the amp meter this winter but in the mean time I connected the alternator to the positive lead on the starter. Matbe I should change the points and see what happens.

Thanks for the input

[Alain Croteau]

About 10 years ago, I experienced similar problem of points burning out after a few short hours of use. I spent a frustrating summer trying to diagnose and solve the problem with no success. I never did find out what the problem was but I overcame the situation after giving up and ordering and installing Indigo electronic ignition. I replaced the system this past Spring, with another new Indigo system, not because it was failing, but as a preventative maintenance measure in preparation for a trip around 4 of the Great Lakes. I've retained the original parts as spares.

Alain
s/v Kemana
Douglas 32

[Mal Leichter]

Replacing the points didn't fix anything this time. Ive put the boat away for the year after a pretty frustrating summer with the A4.

THe following was done this summer
New rotor, cap, wires, plugs
2 sets of points and condensor
new fuel lines
new filters
new Carturator
new fuel pump
emptied and cleaned fuel tank. Put in fresh fuel and treated it
new oil presure switch
new Alternator
Cleaned out manifild
new mixing elbow

Not much else to change!!!

Thought I might replace the distributor with a new electronic one in the spring. At the same time I will replace the coil. If that doesn't do it I will re-wire the primary ignition system.

What else can I do??

Mal Leichter

[26H82X]

I had seen your post while researching through google, which caused me to register here. I will start of with what i do not know.

You may have a coil that does not contain resistant wire, some coils i believe that is not resistant is for the later model cars, since they're computer controlled they're pulsed. ? The older cars may have resistant wire because the points are closed creating a connection to your coil threw the points when the key is left on. This can lead to burned points if the key is on when your in the store, etc,,. Thats my thoughts on that, not saying i'm right.

What i feel i do know is when your points are closed most of the time the coil is consuming amps which causes heat. If your coil was to be over heating then you wouldn't be able to hold your hand on the coil, assuming we're talking about the + - terminal coils on the earlier model cars. If the coil is over heating it is possible that you can drop a water drop onto it and hear it sizzel, boil. If its so hot that you can not let your hand remain on the coil without gaining a possible burn then yes your coil is overheating. you should be able to keep your hand on the coil for atleast a few seconds, if you cant do that then the coil is damaged. Another thing you can do is measure the OHMS of the primary side of your coil. They typicaly read around 1.2 1.5 ohms. If you get a reading uner 1 ohm then your coil is probably damaged.

The Condenser.. Imagine creating a connection to the coil. Up on connection your coil will not spark at its points, Breaking the connection will make an arc. This is called back emf, its like plasma from a telsa coil. Connecting a capacitor in parallel with the points will kill the arc as the points open, the arc i think is damaging your points. When the points is closed the capacitor's/condenser is a dead short, discharging it. When the points Fly open the current would rather flow into the capacitor than fly across your point gap. If that condenser fails then you will get an arc between your points which can be causing them to burn.

Capacitors have ratings also, it is also possible your DC powersource is putting 1 to many volts into your coil, if this is true the back emf when the points open up can exceed the rating of the condenser damaging it.

I would also recommend adding a second external condenser in parallel with the one you have if the power source is to great. If the condenser is rated for 12 volts and your preventing 13 volts from jumping that arc gap its possible it has become damaged. Normal capacitors can be found in scrap electronics rated anywhere from 1 to 1000 volts etc,, if you over volt a capacitor then its ruined, usually blowing its top or not holding a charge.

I am assuming you're getting a really hot spark!

[wmmulvey]

Don

I replaced the points in my A4 in July. The engine started dying again yesterday (sounded like the key was turned off). I checked the points and they are all pitted and burned again. I bought a new set of points and condensor but seems to me they should last more than 10 weeks.

What causes points to burn???

The coil was replaced 2 years ago by the boatyard. Is it possible they put in the wrong coil? Could that cause it???

POSSIBLY THIS

Don't leave the ignition on for more than ~ 3 minutes if the engine is not running. If the points are closed you may overheat the coil and damage it. If the points are not quite closed, they may burn.