Troubleshooting 8N Ignition?

The OEM 3-terminal starter solenoid is internally electrically HOT and operates by GROUNDING the thumb switch by the tranny shifter. Its not uncommon for the little hard to gitt-too middle terminal wire to break. Simple test; ground the screw at the BIG thumb switch. Solenoid operate? problem is INSIDE yer tranny shifter. NOT operate, problem is wire to tranny starter switch. (maybe?) NEXT, ground the middle terminal with a screwdriver blade 'cuz its handy. Starter solenoid operate? definate problem with wire to thumb switch. See how simple that is, eh?

Iff'n Solenoid don't operate by grounding the little middle hard to gitt-too screw. Problem is the most likely the BIG BATT WIRE (-) terminals invisable CORROSION. Remember the 6-volt MANTRA: "keep'em clean, bright, and tight". And don't be fer usin' wimpy furrin made battery cables. Gittcha summ 'arry-chested 'murricum made one-ought (1/0) thick as yer thumb battery cable.

As a general rule, you've replaced all the suspect ignition system ...but... even new parts can be bad. I'd "polish" invisable corrosion off'n the ignition points by sliding a strip of brown paper bagg thru the closed points. Can find a paperbagg? Use a dollar bill. Simple, eh?

Remember, iff'n you "flood" yer engine, you need to replace even yer new sparkies with brand new sparkies because modern no-lead gasoline leaves invisable deposits on the center insulator and them lazy sparkies will leak-off and NOT JUMP the 0.025" sparkie gap. Always check the gap even on brand NEW SPARKIES. AutoLite AL-437's are recommended.

As for why the PO couldn't gitt the OVERHEATED engine to restart; probably warped the cylinderhead, blew out the headgaskett and LOST COMPRESSSION. Smart thing to do would be to do the dreaded compression test. Ford specs: 90psi min (dry). Do 5-puffs min and writter down. Then do a WET, 5-puffs min. Squirt about 1-oz (tablespoon) of engine oil down the sparkie hole. Oil will seal yer piston rings and up the compression over dry. Amount of PSI increase is indicator of engine condition. +10psi, good engine; +20psi worn good engine; +30 tired engine: +40psi really tired engine; NO INCREASE burned exhaust valve or BLOWN HEADGASKET. Simple, eh?

You don't wanna do a compression test? Squirt some oil down the sparkie hole ennyways 'cuz the piston rings have lost their seal just sittin' thar. Engines with NO COMPRESSION DON"T START. Simple, eh?

Recommend you consider the merits of having your very own personal copy of the I&T FO-4 manual. $22, (cheap). Readily available from sponsors of this great N-Board. Most agricultural emporiums. amazon.com, BordersBooks, WalMart books. www.n-news.com also has great archive of implement manuals. Heck, even Ford/New Holland dealers sell it, isn't that amazing? Even my local (byte my tongue) John Deere dealer parts counter has it for sale. Gittcha one and readitt..... ...respectfully, Dell

If you have a solenoid not specifically for the older Ford-style application, it will not work.

If you do have the correct solenoid, one specific large stud must be connected to the battery for it to work, as this stud is internally connected to one side of the solenoid coil.

If it is the correct solenoid, there will be continuity between ONE of the large studs and the small terminal. The other stud will be isolated from the other two.

The battery cable gets connected to the stud with continuity to the little terminal. The starter connects to the terminal isolated from the other two.

Ground the small terminal to energize the internally hot solenoid.. if that doesn't do it.. you have hooked it up wrong somehow.. or it is defective.

Soundguy

get a test lamp or VOM.. First.. get your solenoid issue fixed.. with 3rd terminal facing block, and 'right side' terminal hooked to battery negative ( positive ground system if it is 6v pgrnd system ), and the transfer bar hooked tot he starter.. with a good charge ont he battery.. grounding that 3rd terminal will energize the solenoid.

Now.. you will be able to follow a wire diagram for power. Use test lamp or vom to check power at ignition switch..move over to the coil.. should see power at the incoming primary side.

For front mount 6v units.. when you turn the engine over, voltage should 'bob' from battery votls to ( 2.5-3.5 ) and then back. Basically when the points close.. the votlage drops.. when they open, battery votls again. if a side mount.. voltage should go from battery votls to 0 volts on a 6v unit.. or a 12v unit and 12v coil.

Now.. when the points open is when spark happens.. if front mount.. use a spare plug.. frounded, and spin engine over.. you should see spark.. that's about the 'best' test of the ignition system you can do.

If you don't ahve power at the switch or coil. go back up the line till you do.. then isolate the problem

Soundguy

I'd use your ohmmeter, and disconnect the wire from the switch ( and solenoid ...for safety.. ), and then measure from the switch button to ground.. push the button.. i f the ohm meter doesn't indicate a short.. then your thumb switch is bad.. or the tranny is in gear.. etc...( that switch is tranny interlocked.. won't depress fully if the tranny is in gear.

Soundguy