A demostration showing the effect of a bad condenser on an ignition coil's spark

Using a refurbished 1940s Herbrand coil and condenser tester, I demonstrate how a deteriorated and out of spec condenser affects the spark quality.

[@Portrayalpress]

Super video - love that tester! Thanks for sharing.

[@patriotwarrior_556]

Thanks for what you do. I have an 84 18 foot boat with a inboard stern drive mercruiser....2.5 liter 120hp chevy motor...I had my engine running for over 2 hours...next day started it up...then took to lake....once on the water and it was under a load and or had back pressure on the exhaust from the water it would not stay running...Few times it would start and die and then nothing...few times i kept it running by adding fuel to carb but then it cranked for a while with nothing and then we check and had zero spark....all i have done is clean the points but the points are old and so is condenser....plugs...wires and cap and rotor look good...coil looks newer but was getting hotter then i thought good. 2 times i took it out to the water and each time as soon as i got it on the water it would not stay running?...Any ideas

[@sanclea]

Well done. Thank you.

[@dr.durellshepard398]

Hi Steve, love it all, specially the spark gap and your Simpson. Used one for many years at work. Regards.....Doc

[@steveblancard5566]

Thanks Doc. I used one for 20+ years in the navy. Its like an old friend.

[@michaeleisenbise4278]

This is an incredibly good and well done video. KKudosto you. I am going to share this on all the major Model A Facebook sites.

[@steveblancard5566]

Thank you, glad you found it useful.

[@EkClassics]

I've been working on cars for 40+ yrs and never asked myself what exactly does a condenser do.....how do I tell if it's bad.....what are the symptoms. Granted, many of those years were the electronic ignition era, but I am now doing '60's Lincoln Continentals. I always suggest a full tune up when someone talks about their barn find, but I don't think many know that includes point AND condenser. Thanks for the video

[@steveblancard5566]

Many of the condensers available today are imports and rather poor quality. I tell people if they have a good condenser, dont replace it with one of unknown quality just for the sake of replacing it. I bought a standard products blue streak condenser last year. Blue streak is supposed to be their premium line. It failed within a week with an intermittent internal connection.

[@kylewetherington]

Thank you for this. Do you have a demonstration of how to test a condenser with a basic multimeter? I’m struggling with my Ford 8N tractor.

[@steveblancard5566]

@@kylewetherington If your multimeter can test capacitance, you can use that for a basic test. Also check for continuity, it should not be shorted.

[@alexiskai]

One way this type of condenser problem can manifest is in spark failure under load, i.e., the car will idle well but fail when you try to accelerate. I saw a test on an outboard motor where the correct size of the condenser was .22 mfd. Increasing the size to .47 mfd reduced the peak voltage in the primary winding by 25%. That seems to line up with what you're seeing on the tester.
One thing I'm curious about and haven't had time to check is whether you could diagnose a condenser whose capacity was too small on a Model A engine by using a clear distributor cap (and a dark night) to look for arcing at the points. I'm not sure whether you'd be able to see the points under the rotor though.

[@steveblancard5566]

Good question. You might be able to skeletonize the rotor for better viewing. There is lot of extra material there.