70 Diesel MAG. problem--WHAT NEXT

Yours loosing his cool,

John

PRELIMINARY: Make sure the plug wires are good, well connected into the coil n making good contact, and both plugs are attached n grounded. Does she spark then????? ? if not, see below:

1) Next, insure the points on that coil are opening n closing,,,,, ,,not heavy gray oxide coated (if so try to clean/buff/polish them n re gap) but if badly burned or pitted or carboned up, replace them.

2) Turn the ignition on, place a test lamp (or voltmeter) on the points terminal, crank the pony over, and the lamp MUST flash ON when points are open and OFF when points closed.

3) If the lite never comes on, the the coils primary is open (no voltage can get to points, open circuit),,,,, , or the condensor is dead shorted,,,,, or the points or wiring to points is shorted out.

4) If the lite never goes off, the points arent closing or arent well grounded.

5) The coils seconday high voltage winding between the plug leads should be continuous but very high ohms (a few thousand or so) while the low voltage primary should be continuous NOT open) but very low ohms.

6) If the lite on the points never comes on when they are open and the condensors not shorted out (should read like an open circuit) nor the points or wiring shorted and the coil has that classic burned electrical/insulation smell, it may well be a burned up bad/open coil (will not show continuity) perhaps caused by the ignition left on too long which happens???

Simple as thaT, HOPEFULLY LOL

Let us know, Good Luck n God Bless

John T

Now on the two cylinders out�That distributor uses the lost spark type of ignition so when BOTH plugs on a cylinder quit sparking it means that whole bank has quit..

For that system to operate, one spark plug [or the plug wire] MUST always be hooked up & grounded for the other to spark as one plug & wire is the other�s ground path.. If you pulled BOTH plug wires before checking for a spark reconnect one [or ground the plug wire] before checking for a spark on the other..

If the spark was checked per above then NEXT on the list would be to look behind the coil on the bank that isn�t sparking & MAKE SURE both plug wires are fully inserted into the back of the coil [a common problem on the non screw in type coil]..

Next pull the pony distributor cover & verify the points for the malfunctioning side are actually opening & closing as you crank the pony over.. If the points are opening & closing place a 6 volt test light [make one from a small 6 volt bulb] between the condenser screw & ground for that side, then crank the engine over�If the light flashes on & off while cranking you probably have a failed ignition coil on that side [again common if you have ever left the pony ignition switch on for long without the pony running]�Give the coil a sniff & if it smells burnt replace it.. You can also use a voltmeter for the above test but some cheap voltmeters won�t keep up with the points opening & closing so will give a false reading..

If you suspect a bad coil in the above test you can use an ohmmeter to test the coil but in a lot of cases that won�t show a failed coil due to it having been overheated as the resistance will still be close but the insulation will have broken down inside the coil.. If you want to test the resistance in that coil give me an E-Mail & let me know if you have the plastic covered coil or the original coils & I will send you coil specs & testing information.

If the light doesn�t come on at all suspect shorted points or a shorted wire between the coil & condenser, or a shorted condenser.. If the light stays on all the time while cranking suspect the points are oxidized [try cleaning the points] or not closing..

Those pony coils are pretty delicate in the pony ignition systems so won�t take much abuse without burning up.

CAUTION: Don�t leave the pony ignition on for long while working with or testing that system or you will surly burn a coil up. While working with one side on that pony distributor place a piece of cardboard between the points for the other side [a match book cover works good] & that will protect the coil on the non testing side.

I�m sure you have question on the above so post back with any questions on the above..

Once you get that pony ignition system working again F-I-T & myself have a great little pony coil protection circuit that is a great addition to that tractor to protect those expensive pony coils from damage if the ignition switch if ever left in the on position without the pony running [it works great].. Talking about that now will confuse the troubleshooting of your system as I�m sure the above is complicated enough.. Once it is up & working go to the web site below [pony coil protection] & read the article on installing a pony coil protection circuit..

[email protected]

• Pony coil protection info

I have a follow-up.

1) Do what Clooney says

2) If you don't have patience, the 70 Diesel is probably the wrong tractor for you! :)

Good luck!

Frank-in-Tallahassee
70D // 855 // VAC // Farmall Cub
[email protected]

• F-I-T's webpage.....ALWAYS under construction....