wd ignition problem?
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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=110993
Printed Date: 14 Sep 2025 at 2:03pm
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Topic: wd ignition problem?
Posted By: kev/ont
Subject: wd ignition problem?
Date Posted: 25 Aug 2015 at 8:10pm
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Dressing up a wd for a colleage of mine. Unit has been converted to 12v in the past and fellow wanted to keep it that way so it has a 10si 3 wire alternator with a charge light mounted in the dash. When checking the battery voltage with engine running, my bluepoint digital voltmeter goes nuts (shows between 3 and 9 volts) when i come within 2feet of the tractor (no leads connected). When i touch the batt posts it spikes on the 20v scale. I dissconnected the alternator completly and it does the same thing. Batt reads 12.77 volts with engine off. I assume i have an ignition problem. Engine runs great. Do I need suppression wires? Different coil? Wires are multistrand and if i'm not mistaken aluminum. Coil is 12v coil tractor came to me with. Connected with neg side to the distributer. |
Replies:
Posted By: CTuckerNWIL
Date Posted: 25 Aug 2015 at 8:26pm
With the engine running, is it possible that digital is picking up something from the alternator? Remove the belt while running the engine so the alternator is not spinning or get an analog meter 
------------- http://www.ae-ta.com" rel="nofollow - http://www.ae-ta.com Lena 1935 WC12xxx, Willie 1951 CA6xx Dad bought new, 1954WD45 PS, 1960 D17 NF |
Posted By: DiyDave
Date Posted: 25 Aug 2015 at 8:29pm
| Check the ignition for cracked wires, cap, other bad components. |
Posted By: kev/ont
Date Posted: 25 Aug 2015 at 8:44pm
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I was thinking of finding an analong meter. I will remove the belt and try that as well. Hadn't thought of a crack in the cap. It looks good but that doesnt meen it is. Wires are new so i hope they r not an issue. But i suspect they might be. Thank you both |
Posted By: kev/ont
Date Posted: 26 Aug 2015 at 10:16am
| Bump |
Posted By: DaveKamp
Date Posted: 26 Aug 2015 at 3:29pm
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Hi Kev! Okay, so obviously you've narrowed it down to being engine run/ignition related. Since you noted your meter being erratic just being close, I'd bet that two things are happening here: First, the meter's input impedance must be very, very high... in order to be that sensitive, it either MUST be, or it's got dead batteries... and it's probably an auto-ranging meter too. Second, the ignition system IS imparting a certain amount of 'noise' into the electrical system that 'APPEARS' to be substantial, but more likely that it's simply not the case... you probably have enough AC noise (from the ignition) appearing in the DC circuit, to be misinterpreted by the digital meter. A weak battery in the meter CAN cause it to do this, particularly if the meter has a high input impedance. It may be that your ignition condenser is less-than-good. It may be that your ignition coil ground is less than good. (mounting bracket wrapped around coil isn't always a good ground path. A lower-impedance analog voltmeter would certainly reduce the possibility of errant readings. Another thing that MAY yield a more predictable answer, is to repeat your test, but with the headlights on... as the headlights will serve as a low-enough impedance load that any AC signals that result from aforementioned sources would likely be absorbed at a low impedance level. ------------- Ten Amendments, Ten Commandments, and one Golden Rule solve most every problem. Citrus hand-cleaner with Pumice does the rest. |
Posted By: kev/ont
Date Posted: 26 Aug 2015 at 6:45pm
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Thanks for you reply dave. Now that you mention it, the low batt indicator is on in my meter. Hadnt run into this before as i normally work on diesels. I have a new condensor here which i will try if a new battery in my meter doesnt solve the issue. I did do the test lights on as well. (Forgot to mention that in my post). I also did it with the meter attach to a set of booster cables so the meter was away from the tractor with the same result. Thanks so much for the suggestions. I will definatly try them. |
Posted By: Dnoym N. S. Can.
Date Posted: 26 Aug 2015 at 7:43pm
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Hi Kev i can`t help you with this but i did come across this before one was six volt with a generator one was twelve volt with and alternator and one was a twelve volt with a generator i tried two digital voltmeter and my snap on analog voltmeter i try twenty feet of wire and when i connected got the same meter goes nuts i don`t know .. take the meter and try on a car and it work find got me stump if you find out i would like to know as well good luck B:-) Dnoym PS where Steve when you need him lol |
Posted By: kev/ont
Date Posted: 26 Aug 2015 at 8:04pm
| I will definately post when i solve it. It is a strange one for sure. |
Posted By: Steve in NJ
Date Posted: 28 Aug 2015 at 6:38am
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Put new Batteries in your meter. ------------- 39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife |
Posted By: Dnoym N. S. Can.
Date Posted: 28 Aug 2015 at 7:35pm
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i don`t think it dead battery http://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=nboard&th=796168" rel="nofollow - http://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=nboard&th=796168 http://forums.yesterdaystractors.com/viewtopic.php?t=828201" rel="nofollow - http://forums.yesterdaystractors.com/viewtopic.php?t=828201 http://www.moyermarine.com/forums/showthread.php?t=6325" rel="nofollow - http://www.moyermarine.com/forums/showthread.php?t=6325 B:-) Dnoym |