Bad Out Of The Box

This is from my brother Steve in WI:

This is a photo of the rotor in the distributor on our 722 Bobcat. The 722 has a 98 CID Ford gasoline engine, it's an industrial version of the engine that I think was used in Pintos.

The distributor is made by Bosch. Parts are hard to find. Our local NAPA guy was able to cross reference the Bosch numbers and get NAPA stuff.

After installing all of the new stuff I expected the Ford to crank right up. Much to my dismay it was completely dead, no fire at the spark plugs at all.

It had me baffled. Thinking maybe it was a bad ignition switch I checked the power to the coil, it had 12 volts in both the 'run' and 'start' positions. I checked the new condenser, even replaced the coil and spark plug wires. Still no spark.

Yesterday I cranked the engine while my helper held the primary wire from the distributor close to a grounded part on the engine. A spark was there but we still had nothing at the spark plugs.

I pulled the distributor cap and rotor off and checked them with an Ohm meter. The cap was good but the brand new rotor was open between the center contact and the tip of the rotor.

If you can see it in the photo, the center contact is a silver color, the tip of the rotor is copper colored. It's all sealed in but apparently it's made with two parts of metal and the two were not in contact with each other.

To make sure of things, I took my VOM along when I exchanged the bad rotor at the NAPA store. The replacement rotor did show continuity between those two points.

The Bobcat likes the new rotor a lot better. It sure was good to hear the Ford come to life, I was beginning to wonder if it ever would.

I have run into bad spark plugs and bad condensers right out of the box but never a bad rotor. Before I checked it yesterday it hadn't occurred to me that a rotor could be defective.

BJ at NAPA has been in the parts business for a long time. He had never seen it before either.

It is even marked Made In USA, could understand it if it had been made in China or Mexico.

I have to ask, is that a noise suppression resistor in-between the contacts or is that something else? I've never seen a rotor that didn't have a one piece conductor, but I don't have many distributors left anymore.

I'm surprised the rotor didin't have to pass a continuity inspection and receive a verification mark before it went in the box. Those steps add to the cost of the parts, but it's minimal compared to the cost of selling a defective part.

Thanks for posting!

That's a new one on me. And I'm approaching 6 decades!

I have seen it ONCE in all of my life. It cost me a fifty mile service call on a tractor we had just sold a fellow. It was a JD 3020 gas. He had boughten it from me a few months before. He had wanted the parts needed for a tune up included in the deal. He had ran it for a while and then changed all the oils and filters. HE did a tune up on it at the same time. HE called me as the tractor has started and ran maybe ten minutes an then died. He could not figure it out. It took me a while to find it too. I still have that rotor button in my tool box. It is like yours in that it has zero continuity between the center contact and the end.

So yours makes the second one I have every heard of. The one I had was a Delco system.

The part will end up in the trash, but that doesn't do you any good for all the time you lost. In a case like this you should be compensated for your time. Don't hold your breath for that to happen. Stan

I have been working on one of my tractors the last couple days. It ran 3 years ago...anyway, I pulled the carb and cleaned it up, cleaned out the tank and put in fresh gas. No go.....no spark. So I put in a set of NOS points and condenser that I had on the shelf, still no spark. New rotor, no spark. Googled how to test the coil, coil was good. Swapped caps and plug wires from a known good tractor, no spark. Got the meter out and checked for shorts, couldn't find any. Slept on it a day, went back and decided to check continuity with points closed....no continuity on new points! Hit them with a little scrap of sand paper...checked for spark and tractor started on 3 cylinders. So, it can happen with points, too!

Eldon, that is common on points. Many of them, especially the ones shipped form overseas frequently have a coating on the contacts to keep them from oxidizing during shipping and the boat ride. I saw it the first time when I was working in an auto parts store while going to college 45 years ago.

Did they ever make a rotor with a gap in it to boost the spark through a fouled plug? I always knew it worked, but never really understood why until someone explained it on here!