Hard-starting 15-30

Al in WI · Apr 17, 2009

I recently acquired a 1928 McD 15-30, complete and in pretty decent shape. However, the only way I can get the tractor to run is by pull-starting it (which is tricky when you're all alone). I have not been able to hand-start the tractor. I'm suspecting a weak magneto. Is there any simple way to check the mag/spark on these tractors. I believe it has the original IHC magneto.

spiffy1 · Apr 17, 2009

For the purpose of starting, it's easy to check the mag. If it's running rough etc, you need keener ears or better equipment than I to diagnose between condensor and coil break down, ect.

Put #1 (or any wire of the right length) wire on a spark plug and sit it on the oil cover. Engage the impulse [a '28, if original, I believe is E4A with manual impulse], and crank it over while watching the sparkplug.

Also, you can pull the 4 bolts from the bottom [note which # and wire {the wires may not be in the 'book' sequence} just fired so re-timing is easier] put two back in and stick in a vice for the easy viewing while you index it with the impulse engaged [if the impulse works you'll need a piece of barstock, a screwdriver or really strong wrists!].

If it's running good after pulling, I'm more inclined to think rings, valves, or carb. Oh, it will likely want a crank or two with choke first if you have the R style [if the exhaust is out the hood instead of side, you have an updated carb/manifold] carburator.

Finally, instead of pulling it why don't you throw a belt between the pulleys? Still a pain, but certainly safer!

Al in WI · Apr 17, 2009

Thanks for your suggestions, Dan. Actually, I have been starting it by belting it up to another tractor, but I have a feeling that's pretty hard on the clutch of the driving tractor.
Anyway, once started, the old 15-30 runs very rough - sounds more like my Deere GP. I assumed that this was a carburator issue, but you seem to be suggesting that the rough running may also be due to ignition porblems.

spiffy1 · Apr 17, 2009

Dan? Or was that in reply to my post?

Anyway, it could be either side; I used to get lucky often enough with a mag hot on the bench then firing fine on the tractor, but either years on the mags or luck itself caught up with me, and I recently realized while trying to pin down some rough running in the neighbor's 22-36, both my Regular and F-12 need some mag work, and my 22-36's isn't exactly perfect either.

spiffy1 · Apr 17, 2009

(quoted from post at 22:37:07 04/17/09) I have a feeling that's pretty hard on the clutch of the driving tractor......
sounds more like my Deere GP.

I don't think it really abuses the clutch, but maybe.

Sounds like a GP..... stuck valves?

El Toro · Apr 18, 2009

Pull one the plug wires off when its running and hold it away from the plug 1/4" and see if it has a hot blue spark. The valves may not be seating causing it to start hard and rough running A valve job may be needed.. Hal
PS: Use a pair of insulated pliers so you don't shocked.

Al in WI · Apr 18, 2009

Sorry, Spiffy1, I have no idea where "Dan" came from. The tractor does have very good compression (my sore shoulder will attest to that), so wouldn't that indicate the valves are in good shape and functioning properly? Meanwhile I'm going to do some more checking on that mag per your suggestion. Thanks again.

gtx1967jewison · Apr 18, 2009

sounds to me like a stuck/non-functioning impulse coupling on the mag. spring-action needed for hand-cranking or no/weak spark. highly doubt its valves rings or etc or there'd be problems while running too, especially with valves.

spiffy1 · Apr 18, 2009

No offense taken, only confused because with modern view [which I'm using] vs. classic view sometimes I think I misinterpret the reply trail.

If you have good compression, you should be able to rule out the rings and valves (which still could be set wrong if good cold and erratic hot, but doesn't sound like the case).

As just noted, you'll have to listen for the impulse (the E4A you can see and hear, but have make sure to manually trip it before cranking), it could be stuck; but if it's running rough it sure could be coil or condensor or points instead or as well as the impulse.

Good luck!

Al in WI · Apr 18, 2009

I checked the magneto on my work bench, and it generates a fat, blue spark. So it seems the mag is in decent shape. I tried again to hand crank and I was able to get it to 'pop' a few times, but not run. Next time I work on it, I'm going to drain the old gas out and put in a few gallons of fresh gasoline. I know that's one of the first things I should haver done, but the gas that was in the tank smelled relatively fresh and I didn't think it would be a problem. But I know that you can't assume anything about the fuel available these days and that it goes stale very quickly.

LenNH · Apr 22, 2009

Off the wall thoughts:
Are the magnets strong? They do weaken with age. Weak magnets = weak spark.
A good hot mag and a good impulse should give you plenty of fire for starting. I knew people who thought they had to spin an engine to get a hot spark, but I think they were wrong to do this with a mag that had a good impulse, because when the coupling releases, it really spins the armature around.
On the Fordson, which did not have an impulse, you had to give it a good whirl to get a good spark, and maybe that's where people got the idea of spinning a motor. That's also where they got broken arms when they spun and pushed down on the crank just before the engine decided to kick back.
I don't know if this is ever a problem, BUT....if the mag was not well grounded, the current returning through the engine would have a poor path. Nice shiny base and support bracket? Maybe the ground is through the coupling, so I could be off base. Just thinking out loud, and somebody who deals with these things more than I do anymore can tell me what I'm full of (nicely, of course).

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