I killed my Ford 8N ... now it won't start

[Soot]

1.) I know I'm not the first to do this but I tried to jump start my 8n with my pickup before I knew anything about the tractor. Believe it was flooded but not relevent now. Didn't realize there was a problem until the jumper cables started to melt.

2.) bought shop manual etc. learned about 6V pos ground etc. started replacing likely electrical parts and still can't get it started. Very weak to no spark.

3.) I read every thread I could find on this and other forums, but have not been able to solve my problem.

So here is what I have and what i've done thus far. It is a newer 8N, 1952 I believe sn starts with 566, side distributor.

Starter turns motor well so solinoid and starter seem to be ok.

I have replaced the battery, ALL wiring, cleaned and reattached all grounds, replaced distributor rotor, points and condenser, coil, plugs and amp meter. Plug and coil wires are all from prior to the killing but were new before that. However, the problem appears to be before the plug wires. Have new ignition switch and starter foot switch, but have not installed them as the old ones test out good. I see no reading on the amp meter when I depress the starter switch although I don't know if that is telling me anything or not.

I have double checked the wiring to make sure the coil is wired correctly and can confirm that it is.

With ignition switch on, using a volt meter, I can see that I have 6V going to the coil. I'm getting very low voltage to the distributor.


The pole which attaches to the distributor body and then on to the points shows some voltage, less than one volt, when I go to ground. I get the same reading when I go from the coil center post to ground. I know nothing about coils ... what should I be seeing from there.

I also tried to check this voltage while depressing the starter and saw voltage jumping from 0 to ~6 although that may have been caused by me moving the test leads while trying to hold the starter down.

I tried taking the generator and voltage regulator out of the loop by removing the leads from the VR to better isolate the problem and seem to observe the same result. I now realize in my test the "B" post on the VR was still attached. I don't think that is a problem but may be relevant.

I have exceeded my knowledge of ignition systems on any engine.

Suggestions on what to check next or if the coil is bad even though new or where to start if I need to start over in my replacement, cleaning, reattachment process?

 

[KennyV]

When you replaced the points, did you get them properly gapped? Are you sure they are making and breaking?
Is the replacement coil a 6volt coil? That is assuming that you left it 6 volt.

Most 8 & 9 N fords have been converted to 12 volt. You have replaced more things than necessary to make this conversion. KennyV

 

[Cocre]

Pull a plug, connect back to the plug wire. Lay it where the threads can ground against the engine but you can see the gap. Turn ignition on, try to start the tractor and watch for a spark to jump the plug gap. If it sparks it is probably a fuel issue. No spark, make certain you are grounded and try again. No spark, run a hot wire from the negative (not the ground) to the coil (mine is front mount with only one wire going to it, yours probably has two, it may be identified which is - and +). No need to turn the ignition on, try to crank it. Look for a spark across the gap. If it sparks your problem is probably between the battery and the coil, no spark and the problem is from the coil to the plugs.

If you hurt yourself (or the tractor) doing this, don't blame me.

 

[whistlepig]

Even in good conditions 6V is hard to start. A damp day will make them very hard to start. If the starter motor turns the motor over well check for arc at the plug. If there is not a good arc at the plug it could be one of these things: A bad condenser. My biggest problem. I have bought several brand new condensers that were bad. A bad distributor cap. Check for corrosion on rotor contacts. If the distributor cap is old or dirty replace it. The point gap won't affect your arc at the plug that much. The tractor just won't run well if the point gap is off. And check your timing. It won't start if the timing has slipped. A 6V system won't tolerate much foolishness. Things have to be crisp and clean.

 

[Soot]

Thanks for the replys all... no spark continues to be the problem

Kenny - it is 6V ... gap set to .015 (was reading another post that said on a newer 8N like mine it should be .025 so I need to check that in the manual but they are opening and closing properly.

Cocre - will try the jumper from battery to coil this morning, but I am pretty sure (since I have 6 volts coming to the coil, that the problem is from coil to plugs.

Whistlepig - assuming jumper test shows problem between coil and plugs, I am going back to the distributor this AM and starting with the points and condenser. I was reading somewhere that it is possible to short the condenser to the distributor housing which would kill the spark. You said you had problems with new condensers. How do you test a condenser?

Anyone is there any easy way to test the new coil on this old guy?

 

[Redneck in training]

The coil generates high voltage when the points open (It discharges energy stored in the magnetic field when it collapses). Together with condenser it creates an oscillations throwing several sparks. The coil could throw visible weak spark (because it is short and single) even without condenser.
Assuming you have a Multimeter you can check condenser by measuring resistance between the body and the wire coming out of it. Do not touch the condenser and the wire during measurement. Your body will skew the measurement. If the resistance is low the condenser has short or leak. If the condenser is good you should see the number on the Multimeter start at low value and then within several seconds rise to high value (the meter will charge the condenser.) Then reverse the polarity and you should see the same. If the meter shows open circuit right away there is some break inside of the condenser.
If the condenser is bad the points will arc a lot.

Take the disributor cap off. Turn the engine so the points are closed. Remove the cable from the coil to the distributor and place it somewhere on the engine so it can throw a spark. Turn ignition ON and use insulated screwdriver to open the points. If the coil throw sparks the problem is the distributor.

 

[Egon]

What is the compression like?
Do you still have the manual crank?

 

[jinman]

Take the disributor cap off. Turn the engine so the points are closed. Remove the cable from the coil to the distributor and place it somewhere on the engine so it can throw a spark. Turn ignition ON and use insulated screwdriver to open the points. If the coil throw sparks the problem is the distributor.

That's exactly how I do it. Then, to show that the points are working, I replace the cap and use the starter to turn the engine over and watch for sparks at the wire from the coil. Then I put the coil wire back into the distributor cap and pull a sparkplug wire and repeat the test with the starter to show that the cap and rotor are working properly. Often, the rotor or cap is not seated properly and the problem is that the spark from the coil is not getting through the cap and rotor to the plugs.

 

[Soot]

Thanks for more good stuff We have about 6 inches of snow here and animals to deal with so I'm going to have to wait a while to test but the info on testing condenser and coil is exactly what I needed.

I also have confirmed that points gap should be .025 instead of .015 so will adjust that while I'm at it.

I'll let you know how it turns out.

btw Egon, compression is good (using thumb over plug hole method) and no I do not have manual crank... Wish I did it would help in turning engine to exact spots to get points open and closed. I assume it was a square head or something other than what I would have in the way of large sockets.

 

[Egon]

Lisle 19380 Spark Indicator - Toolfetch.com

one of these is real handy for testing plugs.

Can't remember the crank configuration but there are more than one. They are designed so they slip off when the engine starts.

If the handle has a roller on it the crank just may keep spining till it makes contact with your chin!Hurts