Jump to content

Nominations for Tractor of the Month
Garden Tractors and Parts on eBay



Photo
- - - - -

Now What?


  • Please log in to reply
11 replies to this topic

#1 Ryan313 OFFLINE  

Ryan313

    PK Fanatic

  • Super Moderator
  • Staff
  • -GTt Supporter-
  • Contributor
  • Member No: 7087
  • 3,239 Thanks
  • 5,159 posts
  • Location: Wallkill, NY

Posted October 23, 2012 - 05:31 PM

I replaced the condenser, and the coil on the Case 195; It still has no spark. I got the test light out and I have power to BOTH of the the terminals on the coil, but not out to the plug. I stuck the test light right into the coil where the plug wire attaches and nothing! Advice?

#2 MH81 ONLINE  

MH81

    Proud to be Deplorable

  • Staff Admin
  • Staff
  • -GTt Supporter-
  • Contributor
  • Member No: 802
  • 27,210 Thanks
  • 28,585 posts
  • Location: N. W. PA

Posted October 23, 2012 - 05:39 PM

Ryan, if this is a regular coil, (automotive type) you should only have 12v on the wire going to the points when the points are open. When they are closed, you should have 12 on the one side and 0 on the other.

I'm thinking either you have bad points or a break in the wire. Possible a loss of the ground to the points?

#3 jms180 OFFLINE  

jms180

    Tractorholic

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 1266
  • 913 Thanks
  • 1,204 posts
  • Location: Harvest Alabama

Posted October 23, 2012 - 05:44 PM

if you have 12 volts at pos. terminal of coil the neg. terminal of the coil connects to ground through the points. Points should close at TDC on compression stroke. Boom fire if fuel, spark and compression.

#4 Farmlife OFFLINE  

Farmlife

    Tractor Whisperer

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 12309
  • 1,232 Thanks
  • 1,461 posts

Posted October 23, 2012 - 05:53 PM

most of my issues with no spark have been rust on the points of the magnetto or flywheel....however, by the sounds of it.....I agree with MH81, I would deff check the points...possibly stuck open/closed, bad contact between them....

#5 Ryan313 OFFLINE  

Ryan313

    PK Fanatic

  • Super Moderator
  • Staff
  • -GTt Supporter-
  • Contributor
  • Member No: 7087
  • 3,239 Thanks
  • 5,159 posts
  • Location: Wallkill, NY

Posted October 23, 2012 - 06:11 PM

I did not know that the points would do that. I thought that since it had power to both terminals it would work. I will check the points and see what happens.

#6 CASENUT OFFLINE  

CASENUT

    Tractorholic

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 1974
  • 501 Thanks
  • 865 posts
  • Location: Sylvania, OH

Posted October 23, 2012 - 06:14 PM

A quick check?
Assuming you do have 12 volts at the + side of the coil, check for 12 volts at the - terminal of the coil. If you find 12 volts there, then for the moment, the coil would appear to be OK.

But we need to find that out. So, disconnect whatever it attached to the negative terminal of the coil. You need a piece of wire a couple feet long that will have one end attached to a clean spot on the metal of the engine so that it finds a good, solid ground. Remove the spark plug, attach the plug wire to it and then lay the body of the plug tightly against the engine so that it makes a good ground.

With the keyswitch turned on, take the loose end of that jumper wire you grounded to the block and swipe it past the negative terminal of the coil so that it makes momentary contact. If the coil is working and you grounded the plug properly etc then you should see a spark jump the plug gap.

A nice, fat blue spark says that the coil is good. No spark says that you either did not perform the test correctly or the coil is defective.

Assuming that you do have spark, then you have now isolated the problem to the points and the wire leading from the points to the coil's negative terminal. If this wire has defective insulation or is trapped under the points cover then it may be grounding out, thus rendering the points useless. So check that wire carefully.

this was sent to me from ta

Edited by CASENUT, October 23, 2012 - 06:15 PM.

  • KennyP said thank you

#7 Guest_rat88_*

Guest_rat88_*
  • Guests
  • Member No: 0
  • 0 Thanks

Posted October 23, 2012 - 06:43 PM

Casenut has a good test. With a test light on the - side of the coil and the points open, you will get a light. I prefer a meter, the test lights will confuse you some times. If I remember right the 195 was a pre '70s model. If you have 12V at the coil, you have problems, unless the coil has been up graded to a 12V coil. If it has the stock coil and been rewired, I would check/ replace the coil. 12V on a 6V coil wont last long. Look for the ballast resistor it should have one.

Test light in the plug wire hole of the coil (when working properly) will blow the test light. I have both the adjustable spark plug test dummy and the inline neon test light. They are cheap and really speed up the troubleshooting on engine problems. $50 now will save you a hell of a lot of time over the life of the test equipment if you are making a hobby out of this, if not auto part stores will loan them for free.

Edited by rat88, October 23, 2012 - 07:02 PM.


#8 JDBrian OFFLINE  

JDBrian

    Super Moderator

  • Super Moderator
  • Staff
  • -GTt Supporter-
  • Contributor
  • Member No: 2507
  • 9,574 Thanks
  • 14,136 posts
  • Location: Hubley, Nova Scotia - Canada

Posted October 23, 2012 - 06:53 PM

The points normally do what Casenut is suggesting so if the points and wiring are good you will see the voltage on the points fall to 0 when they close and go back to 12v when they open. It's when they open that a spark is produced. You need a good connection from the engine chassis back to the battery - terminal for this to work. If the engine uses rubber mounts you need to run a separate wire to provide the connection. Keep checking things Ryan and you will find the problem.

#9 Ryan313 OFFLINE  

Ryan313

    PK Fanatic

  • Super Moderator
  • Staff
  • -GTt Supporter-
  • Contributor
  • Member No: 7087
  • 3,239 Thanks
  • 5,159 posts
  • Location: Wallkill, NY

Posted October 23, 2012 - 06:59 PM

Thanks guys! All good advice!

Jim, I will try that. It sounds like a good way to test it!
  • CASENUT said thank you

#10 Oo-v-oO OFFLINE  

Oo-v-oO

    New Member

  • Senior Member
  • Contributor
  • Member No: 5162
  • 340 Thanks
  • 448 posts
  • Location: Live Free or Die, USA

Posted October 23, 2012 - 08:16 PM

if you have 12 volts at pos. terminal of coil the neg. terminal of the coil connects to ground through the points. Points should close at TDC on compression stroke. Boom fire if fuel, spark and compression.


Two things:

Most automotive coils run on 6V, not 12V - even if the car has a 12V system. There is either a ballast resistor or resistance wire to drop the voltage while the engine is running and there is usually a circuit to deliver full battery voltage to the coil while the engine is cranking over, to provide a hotter spark. Running a 6V coil on 12V will make it heat up and fail prematurely.

Spark is produced when the points open, not close. The collapsing magnetic field in the coil produces the high voltage needed to fire the plug and when the points close the field is renewed for the next time.

#11 MH81 OFFLINE  

MH81

    Proud to be Deplorable

  • Staff Admin
  • Staff
  • -GTt Supporter-
  • Contributor
  • Member No: 802
  • 27,210 Thanks
  • 28,585 posts
  • Location: N. W. PA

Posted October 23, 2012 - 08:28 PM

I agree with all said, but DC theory is what it is. A dropping resistor will only lower the voltage if there is current flow. If the points are open, there is no current, thus no drop. Once he gets a set of points working in there, he should see 6v at the + terminal and 0 at the - terminal if there is a dropping resistor in there.

Coils with internal resistors are a whole different critter. Suffice it to say you'll have 12 at the +, and 0 at the - with the points closed referenced to ground.

#12 lyall ONLINE  

lyall

    Tractorholic

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 2180
  • 1,745 Thanks
  • 1,396 posts
  • Location: State Center, Iowa

Posted October 23, 2012 - 10:12 PM

the way I test a coil if it is good or bad is with an ohm meter.
I remove all wires from the coil
quick test
I check the + to - if I get a reading good for now
second: check the + to coil tower - if I get a reading good for now
third : check the - to coil tower - if I get a reading good for now

this tells me that I do not have a short in the coil

then I check the manufacturer's web site for the specs the I model I am testing
if it check close to the model specs the it should be good
if not close to the specs you got a weak coil and you should replace it




Top