Hard starting B from 2/22/2019

Dan in Ohio

Well-known Member
Location
Mid-Ohio
This a response to an old post from Feb. 22. After following pmarkel's post on his hard starting A I decided to go back to my hard starting B one more time. Sometimes You just have to walk away and move on to something else so I did just that. Right beside the B is my 49 A that had been sitting and not started for 12 years. I decided to get it running and not spend any money doing that. After three days, mostly spent dealing with a rusty gas tank, I got it running and it starts right off like it should.

Now for the B which I have spent money and invested lots of time on with still a hard starting situation. I had one more idea to try since I had read a post on how to check to see if a coil was good ( can not remember who posted that). This coil is new and just one of the new parts I put on the B last fall. Long story short I pulled it off and could not get the reading I wanted to see ( ohm reading of .003). Tried the crusty old one that I had removed and it tested fine . Quickly attached it temporarily and gave it a try. To my surprise it started right up and ran great.

New coil found to be bad.



cvphoto21887.jpg


Old crusty coil that works fine.



cvphoto21888.jpg


Think it was James Howell that posted the coil test . Anyway live and learn, all is right with the world, for now. Thanks to all who contribute on this forum.
 

"could not get the reading I wanted to see ( ohm reading of .003)"

Were you expecting a reading of .003 Ohms, or is that what your meter showed?

Either way, the coil primary from a coil from a "hard starting, but did start" tractor would never read that low, by a factor of some thousands.
 
Should have said I could not get it to read anything on a consistent basis, making be doubt my cheap multimeter and my lack of knowledge of how to use
it but the old beat up green one gave consistent higher readings definitely not the meter or my skills causing that. Quickly connecting the old coil was all
the proof I needed.
 
Is your ohm meter one of those auto ranging type. I hate them. Decimal point moves around for different ranges and some times you can easily miss interpet the reading. Just for kicks I would hook the new coil back up and see if it will start. I don't give up easy. Often other things happen that go unnoticed while trying to get something to work. A 12 volt coil should measure between 2.5 and 4 ohms on primary winding. Closer to 4 normally.
 
pete,

I did try the new one again, no start. Just for kicks I checked with VM again and this is what I got, which should mean it is ok right (6 V coil primary).




cvphoto22113.jpg
 
(quoted from post at 17:14:23 05/05/19) pete,

I did try the new one again, no start. Just for kicks I checked with VM again and this is what I got, which should mean it is ok right (6 V coil primary).




<img src="https://www.yesterdaystractors.com/cvphotos/cvphoto22113.jpg">

A coil that checks "way out of range" in an Ohm test is most likely bad.

But if a coils checks close to "specs" in an Ohm test, it still may be "bad".

A single "shorted turn" doesn't change the resistance value appreciably, but DOES dissipate energy that should have contributed to the spark as heat, making the spark weaker, or, at some point allowing little if any spark.

Coil testers "ring" the windings, which will quickly indicate the condition of the coil.

Even then, a coil that tests "good" may fail in use as the engine (and coil) warm up, then work again when cool.
 

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