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Rick3410

Briggs 16HP Cast iron problem

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Rick3410

Was mowing some tough grass (tall and wet) this morning and my motor quit. Sounded like it ran out of gas. I've been doing some checking and here's what I found.

- Plenty of gas.

- I let it cool down and still no firing.

- Checked the plug and it was bone dry and no spark.

- Tried running the plug wire (bypassed spark plug) to engine block, still no spark.

- Checked the points - no spark. Did a light cleaning, used compressed air and blew them off. Still no spark.

- Just to be certain, added a little gas directly into the cylinder head, replaced the plug and turned it over. Still did not fire.

At this point I'm leaning towards a bad magneto. Would you guys say this is typical of how they fail when they go bad? Maybe overheated and broke a coil winding?

The other thing I think is strange is that the plug is dry. Shouldn't it be wet from trying to start it?

What do you guys think? Is there something else I should try or am I missing something?

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MDB

Just a shot in the dark here. You said that you were pulling it hard when it quit. My thought is that it could be a sheared fly wheel key, that would throw the timing off and result in no spark. I have had that happen more than once.....

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curlett

If you take the engine shroud off and look on the flywheel there is an arrow that should line up with an arrow on the aluminum coil bracket when the points closed, if the arrows line up or are very close the key is probably ok. Or you could just take the flywheel off and look at the key to be sure. I would expect the problem is with the wiring somewhere if its not the key.

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curlett

Hard to say, if the problem is a bad magneto then the easiest thing to do would be replace it and keep the points. The only advantage that I see to switching to solid state ignition is not having to occasionally clean/replace the points. If you take the flywheel off there is an insulated stud that connects the ground wire for the magneto to the kill wire for the engine on the points cover, check to make sure that stud isn't grounded because that would cause no spark.

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Rick3410

My understanding is that if I replace the magneto with a coil, I will still use the points and condenser. The only difference is the voltage required to produce spark for engine start comes from the battery (through the coil) instead of the flywheel (through the magneto). Seems to me that this will eliminate my having to remove the engine (not something I really want to do during peak lawn cutting season). I'm leaning towards this approach as a short term fix because my plan is to do a full tractor tear down restoration this winter. Is my approach logical or am I missing something?

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curlett

My fault, I read your post wrong, I thought you meant you were going to do away with the points. Your plan sounds good to me, just curious what kind of tractor is that?

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HubbardRA

Rick, put a Kohler coil on it and if it works just run it that way. I have a 10 Hp B/S that I did that on over 20 years ago. It is still the best running engine that I have.

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Rick3410

Yes, Rod. I did disconnect the shorting wiring. Still no spark. I think that at least for the short term, the Kohler coil may be the answer. I do appreciate all of the inputs I'm getting and I am overwhelmed by the comments on my tractor. Thanks to all for the kind comments. I'll let you all know how this goes. Thanks again!

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BLT

One last thought, is everything in the point box dry? Also you can roll engine over less plug and move the points, with driver, back and forth to see if that will create a spark. One of my better engined is running on a .013 gap.

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fishnwiz

Just a thought...Be sure the plug wire did not suffer a break or burn thru on a hot cylinder head causing spark plug wire to ground giving no spark.

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Rick3410

I installed a coil this morning and everything is working fine. When I do my winter restoration, I'll find out what the root of the problem was. In the mean time, I'll use the coil and see if I notice any difference in performance from the magneto. I do like to keep these things stock if at all possible. Thanks to everyone for your help! Back in business.

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HubbardRA

From my experience, the engine will start easier with the external coil and run just as good, if not better than with the magneto.

The main thing that the external coil does better than the magneto is that the slower the engine is going, the hotter the spark is, because the coil has more time to charge. A magneto needs engine speed to create a hot spark.

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timflury

When the time comes, might I recommend switching to a Magnetron armature part no. 398811 and sending the flywheel to Briggs here in Milwaukee to get repolarized??

The part costs less than $40.00 and it includes everything you need. New harder flywheel key, and a plug for the points plunger.

I've done this on both a 10hp cast iron single, and a 5hp vertical and I must say I'm very satisfied with the upgrades. The engine still looks factory stock and no longer do I have to mess with points and possibly a bad condenser.

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Rick3410

What is the repolarizing process about? What exactly does it do to the flywheel and how does this process eliminate points?

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Kent

To follow up on Rod's point above. The biggest advantage of running an external coil is that you'll get a very strong, hot spark REGARDLESS of how fast the engine is turning over. To get a good hot spark off a magneto (whether or not points are involved) requires the engine to spin over much faster when starting. This can be a huge difference if/when:

1. Your starter generator or battery are getting weak and it just spins slower, or

2. Cold winter temps slows down everything due to weaker battery (they lose power when cold) and thicker oil...

I've run several versions of ignitions - stock magneto pre-Magnetron with points, stock magneto with aftermarket electronic module to replace points, Magnetron (my HB-216 is this way), and points/external coil...

IMO, the points/external coil starts easier than any of those combos, especially in cold weather...

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