Guest F37Olds Posted March 22, 2007 Share Posted March 22, 2007 The coil on my 1937 Olds is 40 years old and I would like to make sure it's still in top working order before taking a long drive. Is there any way to check it out to be sure? Link to comment Share on other sites More sharing options...
Mark Shaw Posted March 23, 2007 Share Posted March 23, 2007 Checking Ignition Coil Polarity You can test for correct polarity of the ignition coil by using a voltmeter. Connect the negative lead to the (-) negative terminal and the positive lead to the engine block.Set the meter on the highest volt range (these connections are the same whether you have a positive ground or negative ground electrical system). The secondary winding's polarity, which you are testing, is determined by the combined hookup of the battery and primary windings.Crank the engine over (do not start it) and the needle of the voltmeter should show an upward swing to the plus or positive side (do not worry about taking a reading). If the needle swings down to the negative side and gives a negative reading, your coil is hooked up backwards. To correct the polarity, simply reverse coil primary leads.A coil with reversed polarity will have about a twenty percent lower output which may not show up at idle and low rpms, but can cause an engine to miss or stumble under load and at higher engine rpms.From: http://www.fifthaveinternetgarage.com/tech_tips/tech_tips_ign_coil_polarit.html Link to comment Share on other sites More sharing options...
Guest Albert Posted March 23, 2007 Share Posted March 23, 2007 There is no real way to test the coil of its currently working, kinda like a headlight in your car, it may last years, or days, maybe just keep a known good one in the trunk is the best insurance..or if the coil has LUCUS written on it, just replace it now, you never know when a cloud will pass over head...LOL Link to comment Share on other sites More sharing options...
Owen_Dyneto Posted March 23, 2007 Share Posted March 23, 2007 Albert's hit the target square on. Even the professional coil testers that were common in shops years back weren't very predictable in results. Generally, coils begin to show signs of failure first when they are hot; Adequate ignition with a cold engine and irregular ignition when the engine (and coil) are hot is a standard sign of coil failure. Link to comment Share on other sites More sharing options...
Bhigdog Posted March 23, 2007 Share Posted March 23, 2007 I see three options for your long trip.1. replace the coil now and use the old one as a back up.2. Take a new one along as a back up3. Assuming the coil is a "generic" can type, don't worry about it, they are readily available enroute. Even if it is a special configuration type most likely you can Jerry rig one enroute if need be.......Bob Link to comment Share on other sites More sharing options...
Guest imported_49packard Posted March 23, 2007 Share Posted March 23, 2007 It is the high voltage side that usually gives out. It starts leaking to ground. Similiar problem I have had and I am having again is the high voltage connection from coil to distributor. This is the second time in about 2 yrs. The outside coating begins to crack and then starts breaking down. Link to comment Share on other sites More sharing options...
tbirdman Posted March 24, 2007 Share Posted March 24, 2007 I had a bad coil last year but it would only fail after driving for a while. Got towed three times in 2 weekends before I figured it out. Link to comment Share on other sites More sharing options...
Guest stude8 Posted March 24, 2007 Share Posted March 24, 2007 I always carried a "Road Kit" with extra coil, points, condenser, fuel pump, water pump and belts. Never needed any of them, cheap insurance for a pleasant trip. The item you leave at home is what will most likely fail. Stude8 Link to comment Share on other sites More sharing options...
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