Coil Problem?
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=48112
Printed Date: 27 Aug 2025 at 4:53pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: Coil Problem?
Posted By: jyanna
Subject: Coil Problem?
Date Posted: 29 Mar 2012 at 4:21am
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Was in the process of using my WD45 when it just stopped. Seems I'm not getting spark. I have electric to the coil. However, I'm not sure how to test the coil. That's my first question. Second, can a coil just fail? Thanks in advance!
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Replies:
Posted By: Ted J
Date Posted: 29 Mar 2012 at 6:50am
From past experience, yes they can. Had quite a few back in the 50's-60's that way. The car just stopped. No warning, nothing. Sometimes after you let it cool down again, it would start again. But then when the temp got just right, bang, nothing.
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"Allis-Express"
19?? WC / 1941 C / 1952 CA / 1956 WD45 / 1957 WD45 / 1958 D-17
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Posted By: Gerald J.
Date Posted: 29 Mar 2012 at 10:36am
Use a test light on the distributor connection while cranking to see if the points open and close. Loss of spark could come from a shorted wire, condenser, or points not opening because of a worn rubbing block or a loose mounting screw. Stop cranking with the points open. Unplug the spark wire that goes from the coil to the distributor at the distributor end. Hold that a quarter inch from ground, like the block and use a jumper wire to connect and disconnect ground from the distributor primary wire connection. You should get a spark every time you open that ground. You could also stop cranking with the points closed, take off the distributor cover to use a screw driver to life the points arm away from the distributor cam to open the circuit.
One other possible failure is dirt on the points so they aren't closing. The wire check above will show that. With the distributor cap off, see that there's still metal parts on the rotor and that the posts inside the cap aren't too badly burned. All of these things can make for poor or no ignition.
Gerald J.
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Posted By: Brian Jasper co. Ia
Date Posted: 29 Mar 2012 at 10:45am
I'd look at the points and condenser before I just replaced a coil. Do Gerald's test, but make sure you're wearing a glove or have some sort of insulation on the wire end you touch. You'll get a nice surprise if you don't...
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"Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian." Henry Ford
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Posted By: Gerald J.
Date Posted: 29 Mar 2012 at 12:19pm
That surprise is why I called for a quarter inch gap. A good coil should jump half an inch but holding the wire you will get shocked through good insulation every time with a half inch gap. I suspected a truck coil once and on the bench I got an inch long spark, so I knew it was OK.
Gerald J.
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Posted By: Brian Jasper co. Ia
Date Posted: 29 Mar 2012 at 4:16pm
The low tension side will tickle a bit too when the circuit is opened.
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"Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian." Henry Ford
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Posted By: Brian Jasper co. Ia
Date Posted: 29 Mar 2012 at 4:19pm
Yeah, somehow I was thinking the point side of the coil...
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"Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian." Henry Ford
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Posted By: jyanna
Date Posted: 29 Mar 2012 at 4:24pm
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Thanks! Good advice on what I hope won't be a shocking situation.
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Posted By: steve(ill)
Date Posted: 29 Mar 2012 at 4:33pm
Normally i replace the condenser and point. Pretty simple and probably needs it. If still dont have spark, then get the coil.
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Like them all, but love the "B"s.
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