Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

Sign in to follow this  
xenon172

A no spark puzzler

Recommended Posts

xenon172
Had one of those head scratchers today with a Briggs 5 hp that had no spark. It is a 136212 horizontal shaft L head with the most basic ignition system possible, a pull start and a standard kill switch. It is a newer motor, 1995, so there are no points or condenser to make things complicated, just a standard electronic module. First thing the kill switch was eliminated as the most likely problem. There was no unusual play in the flywheel and the magnet seamed OK firmly holding a large socket. Reset the air gap and still nothing which left the module. Picked up a new module and installed it and still no spark. This is where the head scratching begins because there's nothing left since even a bad flywheel key wouldn't interfere with spark. The only component that hadn't been changed out was the flywheel and we had one that was salvaged from a blown engine so we put that in. While setting the air gap there was no question that the magnet in this flywheel was noticeably stronger. First pull and there was a good strong spark. Even though the old flywheel magnet seemed strong it was obviously not strong enough and I don't know of any practical way to check magnet strength. It was an interesting problem that I have not seen before.

Share this post


Link to post
Share on other sites
larry8200
I once read something like "Take a large screwdriver and place the tip on the magnet, if it will hold it there with the handle sticking straight out the magnet is OK". Not very scientific and a little ambiguous. But even if you had some expensive lab equipment to measure magnetic fields, being able to get the values for all the different makes and models seems pretty unlikely. I'm interested to see what get's posted here.

Share this post


Link to post
Share on other sites
MrSteele
I have seen the problem before, but rarely. An old trick my father used when storing engines was to be certain that the magnet was located at the armature, so the magnet would be drawing on something. Not certain if it worked, as all those engines were stolen and sold for scrap, along with the cast iron Clintons and Briggs I had been amassing for the last few years. Occasionally, I get an engine that has weak spark, and by decreasing the air gap, increase the spark. You have to set it so that the flywheel will not strike the mag, and leave some room for expansion. It might not be the best solution, but the ZZ on the walking tractor has been running for years adjusted thusly. I know that the gap is enough for a hot engine, as I use the tractor for breaking ground, it runs hot in that process.

Share this post


Link to post
Share on other sites
xenon172
The old flywheel magnet would have easily passed the screwdriver test which is why we figured it was good. Also set the air gap about .002" below the minimum and that wasn't enough but as far as I was willing to go. I have run into bad magnets before but never one that was this deceptive being only half bad

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this  

  • Who's Online (See full list)

    • JohnMBerst
    • Jonstephens01
    • Bill725
    • BAP
    • kwt
    • gwiseman
    • tripleguy
  • Today's Birthdays

    1. Jcarlton300@gmail.com
      Jcarlton300@gmail.com
      (30 years old)
  • Recent Status Updates

    • dav-1

      dav-1  »  Talntedmrgreen

        Over a year ago, you answered a question I had about the tool bar for my FDT. In your reply dated Dec 31, 2019  you said the spacer, part #16, goes in the bar to allow for up and down depth adjustment. does this mean the bolt has to be tightened at whatever depth desired or does the bolt slide up and down, allowing the lower hitch to free float?
         If it is tightened so the lower hitch and the bar are rigid, then is the depth to be controlled by the shoes? Or by the lift handle?
        Is there any kind of user directions for the tool bar? The Outdoor Power Manual basically shows how to assemble the bar but not how to use it
      · 1 reply
    • tribswede

      tribswede  »  goatfarmer

      ISO a deck for a 6516 H and all the connecting hardware any ideas on where to start?
       
      · 1 reply
  • Adverts

×