Ignition Issue/Failure

[Matthewh]

Ok guys, helping a friend with his M37, and having issues with it running, narrowed it down to an Ignition issue.
Background.
Stock truck, though its had its fair share of wiring add ons, extras, etc. Last fall we did a tune up, including new coil, points, cap, rotor, condenser, plugs and wires. He uses it to plow, farm truck, general homestead needs.
He was hauling a manure spreader and it quit. No stumble, just died. Towed it to his garage, and started to check it over.
We found it had zero spark to the plugs.
Started checking voltage and to the feed side of the coil, we had 24v. With the wire to the points off, had 24v on the other post, when we hooked back up, had 1v. Pulled the wires off the points and found the condenser had failed internally and was shorting to the case, it was a "new" condenser from VPW. Swapped condensers to the old one, bolted everything back together, had spark, so we started it. Ran great for 10sec, then died like the ignition switch had been turned off. Now no spark. Old condenser was mil stock so with a composite core, can't test if its shorted internally.

So what are the chances we burnt up the second condenser in 10sec, and why is it burning up condensers? We set the points to .020, per the Tm and they dont show any signs of arching, or carbon. We did find the contacts on the new cap had carbon deposits on the outside edge of the contacts, it easily scrape off, but odd either way.

Any help or ideas, things to check would be great. He works an odd schedule, so I can check things as I can, but with winter headed this way soon, were wanting to get it going soon.

Thanks

[sturmtyger380]

I just go to the local auto parts store and buy condensers there. And I have had them go bad right out of the box. Me thinks cause they are not made like they used to be.

[Matthewh]

Maybe it was coincidence then that we burnt the second one up a short time after it was reinstalled.

[w30bob]

Matt,

Before you burn up another one just check all the truck grounds. You mentioned lots of wiring mods.........if there's a bad ground between the engine and the frame or the frame and the battery it could cause the condenser to fry. Make sure all the stock grounding straps are present and accounted for........and in good shape. Also check your battery cables. Usually when condensers go bad quickly it's because there's too much current going thru them, which there shouldn't be. I'd throw a voltmeter on the coil as well, just to be sure.

regards,
bob

[Matthewh]

Ah good point about the grounds, never thought to check them out and see there condition.
We did put a digital multimeter on the coil a couple of times, and always got 24-24.5v. Once I measured 35v, but attributed that to a dying battery in my meter, as getting 34v from 2 12v batteries isn't possible.

[w30bob]

Hi Matt,

My bad..........when I mentioned checking the coil I was referring to checking resistance in the primary and secondary coils to make sure the coil was behaving properly.
Sorry about that.

regards,
bob

[Matthewh]

We looked threw the manual and didn't see a procedure to check the resistance, but with my meter I set it to the ohms setting and measured both the aftermarket and the original mil coil and they both measured 1.1ohms. Now that was measured on the bench, nothing was hooked up wiring wise.
If there's a different way to check them, id be happy to try and report back

[Sal]

Matt This might be of some help in testing the coil And you can use a hair dryer to heat it with to see if the reading changes. Also you stated that at one point you get a voltage reading of 35 volts, Was that with the motor running? Because these Generators can put out up too 50 volts when not regulated.

[Matthewh]

When I checked both coils, they were out on a bench, not installed in the distributor. That's when they both ohm'd to 1.1, across the terminals. I'll heat them up and see what kind of reading we get.
The time I got a reading of 34v was with the wires hooked up, but the truck hadn't run, we had cranked it checking for spark, and disassembled the dist again to see what was up. When I got the 34v reading, I double checked with a different digital meter, and got 24v, so I attributed the false reading to a dying battery in my meter, as the battery symbol was lit up.

[m-11]

If you really want to check one out....the details are:-

1. Remove the six screws holding the distributor cap in place.
2. Disconnect the leads to the screw-terminals of the coil. These are the primary terminals.
3. Get an test-meter and set the meter to ohms (resistance);
4. Measure the resistance between the two primary terminals (the screw terminals);
5. Readings should show almost ZERO, just a few ohms at most (usually between 1.5 to 6 Ohms).
6. If you get a higher reading, then there is an internal break in the coil windings and coil is bad;
7. Reconnect the leads to the screw-terminals
8. Check the High Tension side by inserting an ordinary auto spark-plug lead in the HT outlet (the high-voltage central terminal of the coil) with the coil connected up and installed in the distributor, but with distributor cap removed.
7. Fit an ordinary spark-plug into the end of the spark-plug lead.
8. Hold the spark-plug against a good clean metal part of the engine block (paint-free). Make sure you use INSULATED pliers to hold the plug against the block or your hair will curl;
9. Get a friend to turn the ignition switch to "on" and crank the engine;
10. You should see a good spark jumping the plug-gap. If not, then the HT -side of the coil is failing.
11. Disconnect the leads to the screw-terminals. Now test the coil HT-side by connecting one lead of the ohmmeter to EITHER of the primary terminals (the screw-terminals of the coil), and connect the OTHER lead to the secondary terminal (the high-voltage central terminal of the coil) . The reading should be less than 20,000 ohms. Higher than this indicates an open circuit, a very low reading indicates a shorted internal winding.
A reading of around 14,000 ohms is normal.
12. If the coil readings are within the specs but vehicle won't start after running, or cuts out when running, test the coil immediately..... an internal-wire breakage is most likely when coil is warm or hot.

See "PS Magazine Issue 246 page 64 for resistance tests.

[Matthewh]

Update:
Worked on it again today. We started by pulling the cap back off, and cold testing the coil. It was within spec, however we weren't getting power to the coil. So we went back to square one, and pulled the connection apart that feeds the distributor. We found we were getting 24v at the Douglas connection, but not at the bulkhead connector that feeds threw the distributor.
So our issue was the distributor feed wire. We were able to solder a fresh piece of 12ga wire to the old distributor plug, I crimped on a new Douglas connection on both the new feed wire, and the wire that supply's voltage. She fired right up, and runs great. We also patched a rust hole in his intake, and ran some vacuum tube from the distributor the carb, as the old copper lines had been long removed.
My guess was with all the work we did last time, there was only one or two strands of wire that were supplying voltage and they finally failed.
Thanks for the help, glad it was something easy