Mark 58ae Saga Continues...

[threedeesmax]

OK, we're almost there. The motor is cranking over. But I'm getting no spark.

From what I've read on this board, an outboard motor must have three things in order to run:

1. Compression (this motor averages 120 lbs. per cylinder)

2. Fuel (no problem there: new kits are in the fuel pump and in both carburetors)

3. Spark

I have no spark.

The motor has new plugs, gapped at .025, and the points are gapped at .08 - I don't have any equipment to time it with. It also has a brand-new timing belt, installed as per the dreaded $50 service manual.

What do I do now? ALL suggestions are welcome. Please.

 

[emckelvy]

Re: Mark 58ae Saga Continues...

?Question?:

When you had the magneto apart did you happen to spin it over and see if there was spark coming from the flat copper strip that screws onto the coil? Normally what I'll do is ground a long, skinny screwdriver to the aluminum case of the mag and place the tip about 3/8"-1/2" away from the copper strip. Just be sure the screwdriver is firmly grounded to the case of the mag or you're in for quite a Zap!

Any mag worth its salt, that's gonna make enough fire for your motor to run, will throw a hot, crackling blue/purple spark across that gap. If you don't have that, she's not gonna make it when you put it all back together and attempt to start.

One thing to try before you tear the mag back apart, is to remove any external wires connected to the small side screw on the mag. The kill wire from the ign switch connects here and if there's something wrong with the switch it'll kill spark. If you were to short this screw to ground with a screwdriver or jumper wire while the motor's running, it'd quit. Note that the screw is supposed to be insulated where it passes thru the case. If it's touching any metal, no spark.

Another thought, was the spring-loaded carbon contact present in the center of the cap? This transfers spark energy from the rotor to the cap.

If the mag will spark without a cap and rotor, and you get no spark with rotor/cap installed, bet money on a bad rotor. Bad rotor will short out to the magneto shaft and all your spark goes to ground.

If you still can't coax any spark out of the mag, you may have a bad coil. Loosen the screws holding the coil in place, pull it out and inspect carefully. I've had them fail where you can't see until you pull the coil out and find nasty marks where it's been arcing to the case.

Anyway, at least she's turning over, you're making progress and just think of all the valuable troubleshooting techniques you're learning!!!!

 

[threedeesmax]

Re: Mark 58ae Saga Continues...

emckelvy, I took the magneto off and removed the cap, the rotor and the plastic housing. Then I checked the points gap, which was right on the money.

I gave the shaft a spin to see if the points were opening, and I had a finger just a bit too close to that copper piece, and it zapped me, but zap wasn't strong, more like a spark from carpet static. I used a screwdriver near the copper piece, and there was no spark at all.

Looks like I have a bad coil, I'd guess. Does that sound right?

 

[threedeesmax]

Re: Mark 58ae Saga Continues...

And thanks for the troubleshooting tips! I'm saving them in a folder for future use.

 

[emckelvy]

Re: Mark 58ae Saga Continues...

Just another thought, prior to this have you removed & cleaned the points to bare metal?

If the motor has been out of service for a very long time, the points may be "hazed" over i.e. a film on the contact surfaces and then you will get little or nothing out of the mag.

You Most Definitely would have known if there were adequate spark when you used your body as a spark tester!!

Unless you're installing new points, the best way to dress up an old pair for use is to clean them on a thin whetstone (if you don't have that, some medium wet-n-dry sandpaper backed by a flat surface will do).

Once you've cleaned the points to bare metal, polish them nice & shiny with Crocus Cloth. Degrease, reinstall, set gap, test spark.

Note if the points are badly pitted you probably have a bad condenser. I think you can still get the ign parts, look up the old stuff at the Doug Russell site. Or try http://www.oldmercs.com/

If the points are perfect and you don't think that's the issue, maybe the coil. Most of the ones I've seen bad have obvious arc marks but with this stuff getting nigh on 50 years old, the insulation can break down and leave no sign of problem on the outside. Real easy to diagnose if you've got another working mag, Not So Easy if you don't. Probably can check resistance of the coil with a meter (there's that pesky meter again!).

Have Fun.......ed

 

[threedeesmax]

Re: Mark 58ae Saga Continues...

The points were hazed over, as you suggested. Sanded them with 600 grit and got a big fat spark. I reassembled the magneto, installed it, and the motor started right up!

I took it to the lake this afternoon for a shakedown cruise and didn't have a lick of trouble with it. Had a couple of very enjoyable hours on the water.

The motor hadn't been started since 1970 - now it has a new life.

Thanks for your help!

 

[emckelvy]

Re: Mark 58ae Saga Continues...

Most Excellent! I remember the fun I had with my first MK58, $25 off the bulletin board at work, cleaned the points up, unplugged the water pump, and she ran like a champ.

My brother and I picked up an old junky flat-bottomed wooden ski boat for $187.50 and we skied the whole summer powered by the Old MK.

That was Boating on a Budget fer sur! Never even hooked up the electrics, just installed a kill switch and she always pull-started with ease.

Yours is a LOT nicer than my old rig was, bet you got lots of looks out on the water!

 

[Scaaty]

Re: Mark 58ae Saga Continues...

Congrats on getting that puppy breathing agian!!

Hey Ed..pick this up and get crazy again..(think its a "Minimost"..."T" had one moons ago...)
In Stanwood
http://seattle.craigslist.org/sno/boa/321975742.html

 

[emckelvy]

Re: Mark 58ae Saga Continues...

That's a pretty cool boat and I bet that MK pushes it quite well. A bit heavy in the stern though! The guy has dropped his price considerably since first listing the boat.

Actually my brother and I bought a 9-1/2' flatbottom "knee knocker" with a MK25 stock powerhead on a Quickie lower years ago. The motor was a bit 'sick' but it went at least 44 mph and in a side-by-side run, would slowly pull ahead of his 17' Apollo with a M1000 on it.

I rebuilt it, hogged out the reed blocks & front cover, and mounted a 50 HP Merc carb. But it's only run in the barrel since (quite dramatic when you rev the motor up and most of the water in the barrel goes straight up!). The boat's been hanging up in his garage for years.

Guess I need to slap on the new coils I got off eBay, change the impeller, and get 'er back in the water!