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Old 02-17-2013, 02:54 PM   #1
Wilbur
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Default Bad Condenser Symptoms?

What symptoms point to a bad condenser? My 29, which has a new distributor with modern points, acted up something terrible lat night on a 50 mile run. It started with a random miss at 45 mph, and within 15 miles, we were limping along in first gear, bucking and powerless, with an occasional backfire out the carb. It acted as it had in the past, when the sloppy point block on my old distributor allowed the point gap to reduce to almost none. I pulled over and found the gap to be fine. The cap, rotor, points and condenser have maybe 200 miles on them. The coil is not new.

It was blowing snow and we were dressed in full 20's garb to attend the Rum Runners Ball in Cape May, NJ, with 5 miles to go! We limped to the party and left her there for the night. Any ideas would be appreciated.
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Old 02-17-2013, 03:19 PM   #2
Tom Wesenberg
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Default Re: Bad Condenser Symptoms?

What your car did certainly could be a bad condenser. The easy check is to hold the coil wire 1/4" from a head nut and crank the engine with the key on. You should have a strong blue spark. A wimpy yellow spark is no good.
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Old 02-17-2013, 03:29 PM   #3
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Default Re: Bad Condenser Symptoms?

Hey Wilbur,
Hm, long distance diag of your stated symptoms..is crap shoot, but I'll start it off by saying that what you describe could be the results of a failing condensor. However....same symptoms could result from fuel starvation (i.e.-dirt in fuel line/carb float not right). You say you did dist work...'and it acted as in the past'. Well, that's evidence, IMO, that mabe something other than dist is THE problem. Like said, hard to diag from distance, but have you checked for loose/bare wiring/grounds; do you have original ign cable ...is it screwed into dist..just a tad TOO far (that will do it also) Is your dist grounded GOOD to engine or sitting on thick paint? Some place to start,eh. Let us know the fix, when you locat it.
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Old 02-17-2013, 03:36 PM   #4
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Default Re: Bad Condenser Symptoms?

Last night l was thinking maybe a blown head gasket. l'm working on it now and am going to do a compression test and look at the spark jumping. The plugs are all wet with fuel. I had the Tilly carb apart a few months ago, straightened the housings in the oven and have the float set good. The glass sediment bowl looks spotless, so at this point l am leaning toward an electrical issue and will repost later.
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Old 02-17-2013, 03:57 PM   #5
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Default Re: Bad Condenser Symptoms?

The spark looks hot, blue and jumps a good 3/8". Compression came in low, but consistent with this old girl. Between 54 and 65 psi, so the head gasket or a stuck valve is out. The cam nut is tight, but timing may be the issue. Gonna get out the test light and check timing as per Les Andrews red book next. Any thoughts?
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Old 02-17-2013, 04:16 PM   #6
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Default Re: Bad Condenser Symptoms?

I have seen other answers were they say hold the wire near block to check for spark. Are they saying hold it in your hand or with some nonconducter ? I know my model T knocked me about 10 feet.
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Old 02-17-2013, 04:24 PM   #7
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Default Re: Bad Condenser Symptoms?

How many miles do you have on your "new distributor"? Was it running ok before you changed it?
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Old 02-17-2013, 04:26 PM   #8
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Default Re: Bad Condenser Symptoms?

Quote:
Originally Posted by John Kuhnast View Post
I have seen other answers were they say hold the wire near block to check for spark. Are they saying hold it in your hand or with some nonconducter ? I know my model T knocked me about 10 feet.
You should be fine by holding the wire on the insulated part. If not, then the insulation is bad.
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Old 02-17-2013, 04:33 PM   #9
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Default Re: Bad Condenser Symptoms?

Hey, lookie here, just set the coil wire near some steel and let it go, Jack! Anyhow, the timing check went fine. She is spot-on. This new, modern distributor, from Snyder's, has about 200 miles on it and has run fine up to now.

My old one just needed a new point block, but l decided to get a new one because the bushings were pretty sloppy on the shaft.
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Old 02-17-2013, 04:33 PM   #10
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Default Re: Bad Condenser Symptoms?

Some ignition problems can be heat related so if you did the spark jump test with a cold engine
the problem may not show up.

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Old 02-17-2013, 04:40 PM   #11
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Default Re: Bad Condenser Symptoms?

It started with a random miss and gradually got worse. Hmm.. I'm no expert on motors, however, I do know a lot about electricity.

The plugs were wet with fuel- No fuel starvation problem.
The spark is strong and blue- No coil/condenser problem.
Compression is good- Not a valve problem.

A possibility is to look for cracks in the distributor upper housing (the thing that the spark plug straps go to) and the dist. cap. Look for signs of arcing inside the bakelite parts. Had this happen on mine when I first bought it. Drove me nuts trying to figure it out. Same symptoms as you describe. As the arcing continued, it left carbon, which caused more arcing, which made more carbon, etc. Finally, the car barely ran. Replaced the dist. housing and it ran perfect again.
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Old 02-17-2013, 04:51 PM   #12
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Default Re: Bad Condenser Symptoms?

you might have a good spark now but check it while it is acting up with an inline spark tester. alot of times ignition is intermittent, so do your testing when the problem is happening
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Old 02-17-2013, 04:53 PM   #13
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Default Re: Bad Condenser Symptoms?

I had the same problems when I was at the Dallas Meet. I changed the condenser and had no more problems

Easy simple fix
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Old 02-17-2013, 04:54 PM   #14
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Default Re: Bad Condenser Symptoms?

PS. Good idea! We did look for stray sparking last night in the dark, during the snow storm and saw none. However, looking for carbon tracking is a great one. Thanks. This morning, l had the car flat-bedded the 50 miles back home ( that $12 towing extra on my JC Taylor policy is fantastic ) and had tried to start her, cold, at that time with no luck... the plugs were all fouled from limping to the party.
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Old 02-17-2013, 05:00 PM   #15
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Default Re: Bad Condenser Symptoms?

Are condensers voltage specific..as in 12 volt and 6 volt?
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Old 02-17-2013, 05:27 PM   #16
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Default Re: Bad Condenser Symptoms?

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Are condensers voltage specific..as in 12 volt and 6 volt?
No. They do have an overall insulation breakdown rating, probably about 500V for an unpolarized ignition coil capacitor. They often fail in intermittent ways, though.
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Old 02-17-2013, 05:35 PM   #17
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Default Re: Bad Condenser Symptoms?

Ok. Here's where l am. Decided to try to start it up. Installed new plugs, put the same cap and rotor parts back, turned the gas on and cranked her over. No start. Pulled the coil wire off the cap. Cranked it over, key on, and had no spark. Key off, checked for 6 volts at both coil terminals. Good. Removed cap and rotor, turned the key on, put the coil wire near a ground and manually opened closed the points to trigger a spark out of the coil. A quiet arc occurred at the points and, maybe one in 8 times, l got a high voltage spark out of the coil wire to ground. So, whats bad there... coil or condenser? Can anyone explain to me what the condenser does?
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Old 02-17-2013, 06:00 PM   #18
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Default Re: Bad Condenser Symptoms?

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. . . Can anyone explain to me what the condenser does?
The ignition coil is a high ratio transformer. Transformers do not work on straight DC. The magnetic field must be moving to induce electrons to move in the windings.

When the points open the ignition coil magnetic field collapses (moves) and induces an electro-motive force (voltage) in the primary as well as the secondary coil. It's not very much in the primary coil because there are only a few windings in the primary, but it's enough, maybe up to 200V, to jump a small air-gap such as the one between the barely open points. That tiny spark is enough to erode metal away from the points and you'll burn up the points in a matter of minutes. The condenser (capacitor) is an electron reservoir and prevents the points from arcing by absorbing the induced primary voltage rather than letting it arc wildly across the open points.

If you have a solid state (transistor) switch instead of mechanical points there is no air-gap to ionize and maintain an arc, so no condenser is necessary. Example: Pertronix "ignitor" modification. Of course, that mod has it's own set of problems!
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Old 02-17-2013, 06:27 PM   #19
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Default Re: Bad Condenser Symptoms?

Mike, thank you for the explanation. Given the details, what's your opinion of my issue? Is my coil done for?
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Old 02-17-2013, 06:33 PM   #20
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Default Re: Bad Condenser Symptoms?

Am I reading that one in eight times of manually opening and closing the points you got a spark? If so clean the points with a file and regap and try it again
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