Slick start

[DerekM]

My engine became very hard to start. Turns out it’s the slickstart: we took the VIN lead off, the voltage in that powers the unit, and the engine starts perfectly easily like it used to. Has anyone experienced this and how best to fix? A new ss is about $4000 CAD! A painful and perhaps unnecessary purchase considering the engine starts perfectly well without it powered up.

[gyro3816]

SS is $1270 at Aircraft Spruce. That part cost sounds like price gouging. I like the SS and I wouldn’t go without.

[MarkA]

Another option to consider is to replace the left Slick Start mag with a SureFly electronic ignition (the SIM4N is currently $1,755). You'd end up with the same operational effect as the Slick Start - the plugs fire at top dead center when the starter is engaged then advance as appropriate. Also, there would be no more 500 hour inspections required for that mag and it is more or less a drop-in replacement.

[michael.g.miller]

+1 My former SR22 had a SureFly. HIGHLY recommend moving over. Mags are great because they work without electric power, but otherwise awful, dependent on a tiny nylon gear that's prone to failing, and requiring maintenance every 500 hours. The SureFly is basically maintenance-free, gives you the best of both worlds (still have a mag on the other side if you loose electric), and gives you a spare mag you can IRAN when your main one is at 500 hours.

[Rich]

At cranking speeds magnetos produce a truly feeble spark. Plus it occurs at the wrong time. That's why they have some sort of assist during the start sequence. Historically, that was done with impulse couplings. Otherwise it's hard to picture it starting "easily" without some assistance.

I believe there are some DA40s that are fitted with BOTH SlickStart and impulse coupling(s). Somewhere along the line I concluded that fixed-pitch DA40's were such an instance. It's easy to tell if you have impulse couplings. As the prop is pulled through you'll hear a readily audible mechanical SNAP for each mag that has one of these. If so, this is what is allowing the engine to start.

[Steve]

... and gives you a spare mag you can IRAN when your main one is at 500 hours.

Not really. The left and right mags on the IO360-M1A (and most engines) are different P/Ns and are not interchangeable.

[Diamond_Dan]

Slick Start left, SureFly right on mine. Best of both worlds. Was pretty easy to start before the SF but now it's a no-brainer.

[MarkA]

Yep, the left and right mags are different part numbers - the left magneto is a SlickStart “retard” magneto (PN: 4347) and the right is a standard SlickStart magneto (PN: 4370).

With the standard Slick Start installation, the SlickStart module causes the "retard" magneto to delay its spark until top dead center rather than the standard 25 degrees before top dead center during the starting process. As long as the starter is engaged, a jumper on the ignition switch grounds the right magneto so it is not used at all during the starting process. Therefore only 4 of the 8 plugs are actually firing while the starter is engaged.

[Rich]

My engine became very hard to start. Turns out it’s the slickstart: we took the VIN lead off, the voltage in that powers the unit, and the engine starts perfectly easily like it used to. Has anyone experienced this and how best to fix? A new ss is about $4000 CAD! A painful and perhaps unnecessary purchase considering the engine starts perfectly well without it powered up.

Here's what happened to mine some years ago and your symptoms are consistent with this, given the SS + mag 4347:
1. Engine downright reduced to start.
2. SS bench tested OK.
3. It turned out to be the wire between SS terminal 1 and the mag retard breaker.

More info:
When the SS is powered (i.e. starter engaged), two things happen:
1. The lead from SS terminal 3 grounds the p-lead for the left mag, dialing the 25-degree BTDC operation.
2. The lead from SS terminal 1 supplies ~400 VAC to the retard breaker on the left mag.

NOTE: Older SS versions had a terminal #2, which is intended to ground the inactive mag (i.e., left), Diamond's wiring diagram show this as such, but Diamond quit using at all, if they ever did, long ago. Instead the grounding occurs via a jumper in the ignition switch. The newer SS versions (14 or so years back) have no terminal #2 at all, though the information plate may still show its position.

With mag 4343 (in the A4M engine, terminal #1 connects to the left mag p-lead and terminals 2 and 3 are not used. It supplies additional voltage on the primary circuit, relying on the impulse coupler retard function to deal with the timing issue. It basically helps boost the impulse coupler. It would seem to me the only way the presence of the SS could prevent such an engine from starting would be some very odd failure in the SS or an incorrect connection of the the SS #2 or 3 terminals to the left mag p-lead instead of #1.

If you have the much more common -M1A engine with the standard 4347 left mag setup, I have no clue how your engine starts OK with the SS disabled.

[DerekM]

Thanks for all the inputs guys! I’ll look into surefly, and why I was quoted $3k USD when spruce sells for $1270. I have the older SS, my plane is a 2003, so maybe the older one with 4 leads costs more. What lead me to disconnect the VIN (voltage in) lead is the breaker would pop when I tried to start the engine. Like I say, it starts perfectly well now the VIN lead is disconnected so it seems like my engine does have an impulse coupler as well. If I have an impulse coupler maybe I shouldn’t get surefly? Why change something that is working sort of thing.