Home › Forum › Ask A Member › 1938 Bendix TMD spark issues?
- This topic has 6 replies, 4 voices, and was last updated 1 year, 1 month ago by Buccaneer.
-
AuthorPosts
-
December 23, 2023 at 3:33 pm #283438
I got back to the Bendix after taking a “time out”
over frustration on ignition issues, having weak
spark.I had tried two different after-market condensers
that tested at .23 mfd.Today, I installed a .15 capacitor, and reset the points
again. It had seemingly good spark at the plugs, so
I squirted in some fogging oil.
It did fire a “little”. Sprayed some more, and it fired
less. Gave it a shot of ether, and fired a tiny bit.I pulled the port spark plug, and it looked a little “wet”.
With the plug out, attached to the plug wire, and grounded,
I pulled the engine to check for spark again on the port
cylinder, and to my surprise, it ran a couple of seconds.The spark on the port cylinder still looked plenty good,
so I re-checked compression. Surprisingly, the port
cylinder had higher compression at 73 psi, and the
Starboard 67 psi. The compression was probably higher
on the port from the “unburned” fogging oil.
Originally, the compression was within two psi between
cylinders.
If the compression is adequate, then one has to think “spark”?Coils tested good on my Stevens tester, and via the Bendix
manual Model T coil setup.I did notice before I put the magneto back on, that the
rotating magnet had twice as much pull
on one half of the magnet than the other, using a screwdriver.
It evidently has two opposing magnets as it’s a twin opposed
outboard.
I know magnet strength is debatable as far as “starting performance”
on outboards, but at this point, I have no other ideas!
How about you? Thanks.Prepare to be boarded!
December 24, 2023 at 7:03 am #283449I’d think the spark on at least the one cylinder should be enough to get it to run.Maybe just try getting it to run on one cylinder and isolate the “bad side”?
December 24, 2023 at 10:06 am #283450I’d think the spark on at least the one cylinder should be enough to get it to run.Maybe just try getting it to run on one cylinder and isolate the “bad side”?
Stanley, are you suggesting to turn it into a single cylinder engine,
or hope the spark or other ailment, will improve if it’s ran for a while, lol.Prepare to be boarded!
December 24, 2023 at 10:16 am #283452
I would be leaning towards fuel mixture (wet
plug) and – or timing, not enough advance.
Looking through your pictures I don’t see where
you had the pistons out so stuck rings could
be the issue if you haven’t checked them
through the ports..
If you have a compass pass it across the magnet.
If the compass changes from North to South you
have two magnets. If North points to one side
and South to the other its just one magnet.
Focusing on the magnet is like driving down
the wrong road. You’ll never get where you’re
trying to go.
Tubs
A "Boat House Repair" is one that done without having tools or the skills to do it properly.
December 24, 2023 at 11:32 am #283454I looked at one of your other posts and noticed that there is only one primary circuit for two coils. Interesting, I’ve never seen that on any other motors. So if both coils are seeing the same primary voltage, then I wold assume that if only one of them sparks, there’s an issue with the other coil. Have you tried closing down the plug gaps to maybe 0.020″? Or increasing the capacitance of the condenser?
Tom
December 24, 2023 at 12:04 pm #283456No,I was simply suggesting if it would run on one or the other cylinder you could narrow the problem
December 24, 2023 at 1:38 pm #283459Yes, the primary circuits are hooked up in series, and I had never
seen such a system either.Coils were tested several ways, many times, and always passed with flying colors.
Yesterday I switched out the .23 mfd aftermarket condenser with a .15 electronic
capacitor, reinstalled the magnet, and reinstalled a non original ground wire
between the magneto, and powerhead, which I had previously tried.
Reset the points again, and it appeared to have good spark on both old, shorty plugs.I dug out some new NGK plugs and tried them out for kicks, after squirting some
gas in the carb. There may be a Christmas Miracle in the works!It looks like the rotating magnet is “off the hook”.
VIDEO………
https://youtu.be/DxbmXvYkoTYPrepare to be boarded!
-
AuthorPosts
- You must be logged in to reply to this topic.