Two new coils bad? '67 40hp Seahorse

[toadshade]

Just got a rebuild kit for my coils. One original coil was bad and one good (Good coil tested 3200 ohms on secondary btw). When I tested the new coils, I got nothing on the secondary of either. I feel like I could be doing something wrong but I wanted to see if this happens before I send them back. Tested with ground wire to spark wire spike and got nothing on the coil itself. I did not test them to begin with but noticed when I installed the first one and tested my (good) spark wire to make sure I had a good connection. Then I tested both separately and got nothing on either. Are these coils ever suspect right out of the box? They look brand new at least.

 

[F_R]

You do have your meter set on a suitable Ohms range, right? Of course it is possible to get two bad new coils, but highly unlikely.

 

[toadshade]

I use a digital ohm meter so it is a full range. One of my original coils tested fine. I just wanted to know if buying a new, bad coil happened from time to time and I hit the jackpot, or if the chances were so low it is far more likely I am doing something wrong. I don't want to send these back to a mom and pop store just to find out I was doing something wrong.

 

[racerone]

Install them carefully and test for spark.-----Or have them tested on a -----MERC-O-TRONIC ---magneto analyzer.------What coils did you buy ?----Make and part # please ?

 

[toadshade]

I bought them at Vintageoutboard.com part #5181 is the kit. Parts kit specified OEM. Coil I have has 512154 on top.

 

[Crosbyman]

terribly unlucky most probably a testing issue ( no offense) remeasure the old good coil without changing meter settings… do you still have 3200 ohms ??

short the probes ...do you see 0 ohms ?

wet your fingers and measure your body resistance see anything like 20 Kohms +


do you see 1or 2 ohms between the 2 primary leads leads

do you see anything Spike to either primaries ??

 

[toadshade]

I found out I have a bad meter. I borrowed a new meter and got 4.5K ohms across secondary of both new coils and 1.0 across primaries. I realized something was wrong when you gave me the idea of trying the meter on my hand and got nothing. Great suggestion. And by all means, I am not offended. I was pretty certain I had to be doing something wrong. Thanks for the help.

 

[Crosbyman]

great news...eace::canada: thanks for feedback

could be just a bad /old battery inside your meter… change it and see what your get some use 9v some use 2x1.5volts batteries it did work initially reading 3200 ohms on the old coil. all meters need batteries to evaluate resistance...to current flow

 

[toadshade]

First thing I thought of and changed the batteries with the same results. But thanks for the idea. definitely something I could have overlooked.

 

[oldboat1]

Use those new readings as a baseline for future projects. When you get the magneto back together, I suggest that you again test the secondary side -- not necessarily for a resistance reading, but for a backdoor way of making sure you have a connection from the spring connector in the boot to the coil. Put the red lead in the plug boot and the black lead to the engine block or mag plate. No reading means you don't have a connection (likely the plug wire either at the boot or the coil).

 

[toadshade]

Good idea. Thanks, and I suppose anything less than the 4.5K I got on the coil would let me know any issues from the coil to the plug. I can't believe that spike is how the plug wire is connected. I am way too used to wanting a good bolted wire connection. I know it is high voltage so the arc gap can be further, but I would think with all the shaking spinning around there would be momentary gaps between the spike and the wire causing carbon buildup and misfire.

 

[racerone]

They used that connection in the sparkplug boot for 60 years.------And today it is " not good enough " you say ??

 

[toadshade]

Ha! I knew that was coming. I don't mean it didn't work, I just meant I am surprised it works.

 

[Crosbyman]

In the telephony world where I am from … test board technicians would routinely test local copper pairs following customer complaints of noisy lines or hums etc.….on the phone lines. Instead of dispatching a road tech to check things out and sometimes replace a cable pair one method of clearing problems was to ZAP the faulty cable pair with shot of DC 130 volts

Most of the times this would burn or blow off any impurities restoring service, so… I think it is unlikely that "carbon" build up would be a problem on a spark plug wire and boot spike carrying 15-20Kv any carbon oxydation will be blown away as Co2

doesn't mean humidity won't cause problems it will so centering the spike is still needed

Like racerone said… it worked for 60 years

 

[racerone]

And on every plug wire on every OMC motor.

 

[toadshade]

I suppose I got that idea from a Jacobs Ladder I made out of a 18000V neon transformer. Eventually it will stop working because of soot buildup that I have to clean off. That's the only reason it came to mind.