failing condensor symptoms

[Woodie]

I have read many posts/threads where all manner of issues link back to a condensor problem. Could somebody possible consolidate that into a list of symptoms/problems that a bad condensor causes rather than the other way around. And while on the subject if condensors fail out right or just "sort of work" does this divide the list into two categories?

thanks

 

[Guest]

Woodie - you can search the web and find a lot of data on distributors with points. The condensor is actually a capacitor which helps prolong the life of the points. When a condensor fails the points usually pit quickly or weld together. Whenever you replace the points replace the condensor. You can not repair a condensor. There are some who would argue that if the condensor in the distributor is ok why replace it with a part that may be bad when new or fail prematurely. In my humble opinion I think you should replace the condensor when you replace the points. Hope this info helps.

 

[jlaird]

Always have replace points and condencer and roter all together as a package. Never had a condencer fail.

 

[bugimike]

Always have replace points and condencer and roter all together as a package. Never had a condencer fail.

/bcforum/images/%%GRAEMLIN_URL%%/iagree.gif Its not like any of these bits are too costly...just part of a complete tune-up! /bcforum/images/%%GRAEMLIN_URL%%/grin.gif

 

[AweMan]

I can say this about condensers and points:
A failing condenser will make your engine run rough. A failed condensor will make your engine NOT run at all.

Condenser capasity:
An 'over' capacity condenser results in the 'tit' On your points pointing in the 'plus' direction. And, 'under' capacity leads to the 'tit' pointing in the 'negative' direction. Ideally, condenser capacity would be selected so that there is no tit pointing in either direction, and all that is seen at the points is a 'burning' that erodes the contacts away, from both surfaces, equally. This is the result that is most often seen on well-used points.
The value for condenser capacity is not cast in stone. It can be different for different people, depending on how they use their engine. And, not all condensers are made with precision. They vary from unit-to-unit. So, when you buy a new condenser, it is not necessarily going to be exactly the same as the last one.

IF THE POINTS BURN UP OR THE CONDENSER
FAILS FREQUENTLY
1. Check and make sure that everything is well
grounded to the engine block. Condenser failure
is often a grounding problem. Make sure all
grounding surfaces are clean of free of paint,
grease, or oil.
2. If the condenser needs changing, make sure that
the bracket is also changed at the same time. The
brackets are basically a one-shot use part. They
are designed to scratch through the rust
preventative coating on the condenser when it is
installed. In problem applications, scuffing off this
coating will guarantee a good ground.
P.S. I forgot to mention that having a new condenser in your spare parts bag in the trunk is a real good idea even if you never have to use it. If you need it and it is there NO WORRIES but if you don`t have it, and your old one fails you are going to have a lousy day.

Kerry

 

[bugimike]

Good stuff there Kerry!! /bcforum/images/%%GRAEMLIN_URL%%/thumbsup.gif That should help with a lot of condenser questions! /bcforum/images/%%GRAEMLIN_URL%%/grin.gif

 

[jlaird]

Yep needs to go in the WIWI.

 

[regularman]

I have seen many good carburetors torn apart because of a failed condenser. The problem will be erratic. People will think its water in the gas, etc. The main symptom is that the missing will be not on one specific cylinder but any of them at any one time. When you change the points and condenser druing a tune up, save that set as a known good set and keep it for emergencies.

 

[Sarastro]

Sorry, guys, I gotta chime in here and fix a few budding misconceptions.

First, failure of a capacitor operated below its breakdown voltage, or production of a flawed one, of any kind anywhere, is quite rare. I've been working with electronics since I was 9 years old (that's 48 years ago) and, with the exception of electrolytic caps, which have no relevance here, I can count, on the toes of one foot, the number of failed capacitors I've seen. If you have a capacitor problem, it is almost certainly a bad connection, pinched wire, or something similar.

Second, I can't for the life of me see why a higher or lower capacitance would cause points to have a tit in one direction or another. This is electromigration, of a sort, and it depends on the direction of current during the first few microeconds after the points open, while they are arcing a bit. This is not affected by capacitor value. The capacitor value will change the magnitude and frequency of the voltage/current waveform in the circuit, but not its polarity or its overall shape.

Capacitor value does not change the energy available for a spark, either, but it will change the peak voltage. Less capacitance means higher peak voltage but a burst that dies off faster. Possibly you could use this to fine-tune the ignition--or maybe not; depends whether the important quantity is voltage or energy. The caps intended for a particular ignition system don't come in multiple values, though, so this all seems academic. I suppose you could use radio capacitors, with a little creativity, or ones intended for other cars, if you can figure out the value. They're not marked.

 

[regularman]

Most condensers are not like regular caps though. If you tear one apart it looks like a coil of aluminum wound around something. I used to have caps fail in TVs quite often in the drive circuit where they connect to a coil of some kind. There is no elctrolyt in them but they do go bad and its not the connection.

 

[AweMan]

I was taught about points and condensers out of an old motor manual book {Mechanics Bible}. I Just stated basically what the book says on the subject of point-degradation (material transfer from one contact to the other).
Could be that modern technology has found this to be inacurate information if so, I was unaware of it.
Isn`t the capacitance {Condenser} used to prevent arcing of the points? {this is what I was taught}
Different vehicle manufacturers use any where from 25mf to 35mf condensers depending on thier specific ignition system design.
Not trying to argue here, If I have miss information I would like to know.
Kerry

 

[leecreek]

Kerry,
You are running on the same information that I was taught too.

 

[dklawson]

I've never seen the "tit direction" analysis before. I agree with Steve that it does not make sense. I don't dispute that this information may have been in print for years... it just doesn't make sense.

Regularman, you're right, the condensers don't have a liquid electrolyte, but they don't have to either. That's not necessary for all types of caps. The foil and kraft paper layers in the condenser perform the same function.

I have seen one condenser fail in 30 years of tinkering on cars. It caught me totally off guard. I now have electronic ignitions in my LBCs but when I ran points I made it a routine practice to replace the condenser as part of a tune up and always carry the removed unit as a spare in the boot... just in case.

 

[Bayless]

All the condenser (capacitor) does is store up a few electrons while the points are closed then release them back when they open. This helps reduce the electronic "blow" to the points by reducing the arcing. If you take the condenser out, everything will usually still work but the points won't last very long. If the condenser shorts internally then you likely will get no spark at all. A partial or intermittant short could cause unreliable or intermittant spark and certainly rough running if any at all.

An old mechanic once told me that probably 90 percent of the condensers replaced are probably good. Since the cost is so small it just makes sense and cheap insurance to change them every time you change points.

JMHO,
Bayless

 

[AweMan]

Here is a pretty good article on Ignition of ALL types.
There is an explanation of what the condenser does and how it works.
If you would like to check it out
Here is the link. https://www.jetav8r.com/Vision/Ignition/CDI.html

Kerry

 

[regularman]

Condensers going bad is not very often at all, but when it does happen its an inttermittent firing problem that will make you think you have water in the gas or something. The engine surges and spits and pops and backfires, etc. I was on a 300 mile trip to Mrytle beach with my brother once in his 1974 Trans Am. Everything was fine until we got almost to Conway, SC and then the motor started cutting out and would barely run and we were out in the middle of tobacco fields and it was hot as hades. We finally found the right spot to hold the gas pedal down and it ran the best but was still aweful and took us over an hour to go the rest of the way to the beach. Once we got there we went to the auto parts store and bought points and condenser and replaced the condenser first and it ran like new again. I have had several go bad like that but never one that kills the fire completely, it has always been the irratic fire. This happens not just on cars but motorcycle and lawnmowers as well. Its hard to describe the problem until you have it once. I have had good luck putting condensers from one thing onto another and it always worked, so I guess they are all pretty similar. In other words if you have a suspect condenser and can find a tune up kit for a lawnmower, buy it and rob the condenser and use it to get you home.

 

[kcbugeye1275]

I agree with dklawson, go electronic ign, save a set of points and cond. in the tool box.

 

[Bruce_B]

I had a condenser in an MG Midget go bad 'just like that'.
I was driving along fine when the car just died. Replaced the condensor and VROOM.

I now have electric ignition in my BE. I keep a set of condenser and points just in case.

 

[regularman]

Keep a little bit of fine sandpaper and a piece of clean newspaper and a book of matches with the spare points and condenser. I just put on a brand new set of points and the contacts had oxidized in the box and needed some sandpaper run through them. open the points and let them close on the sandpaper first one direction and then the other and pull it out. Then run the clean newspaper through them to remove any grit or grease, oil etc. Use the cover of the book of matches to set the points gap close enough to run good.

 

[Bayless]

Man, talk about nostalgia. I remember that matchbook trick from back when I couldn't even afford a set of feeler gauges ;-) Haven't heard that in years. Thanks for the memory.