Hot start woes...

Thanks to all for your suggestions and input. Here's the latest...

The general consensus is that the problem likely lies with the mags. With this in mind we have pulled both mags (I have 450 hours on the Slick mags). In speaking with Bolduc Aviation people it was pointed out that there is a recommendation from Slick to inspect the mags at 500 hours, but Bolduc feels it should be mandatory to do so. They will inspect and repair the mags.

While we were at it the plugs were pulled, and they looked pretty good. Since we (Larry Kassem, IA, A&P, and I) needed to go to Bolduc with the mags we took the plugs to clean them with the sandblaster. After making them look much cleaner Tim, one of the aces at Bolduc, suggested we check the impedence on the plugs and guess what....4 of the 8 showed very high resistance. He suggested that those be replaced (Tim pointed out that Champion had conducted a study in which they checked resistance on plugs that were stored sealed and to their surprise and dismay some of the plugs which had been stored and never used failed the resistance test!). Given that my plugs were all stamped as being made in 2000, I made the decision to replace all of them. We checked the gaps and installed the plugs. We are now awaiting the mags.

Some of my hangar neighbors suggested considering putting an impulse coupler on the right, as well as the left, mag. The redundancy was thought to be of considerable help should the impulse coupler (apparently normally installed on the left mag only) fail when I am out in the boonies. Darrell Bolduc listened to this suggestion and pointed out that it could be done (at some expense), but that he didn't recommend this. Please forgive my interpretation of his words, but it was my impression that he felt the engineering of the housing upon which the right mag is mounted is not as supportive as the left, and he worried that it might cause problems (again, my interpretation of what he said). Hence, I decided not to install an redundant impulse coupler on the right.

I am feeling really good about the decision to pull BOTH mags and to replace the plugs. Plus, I learned how to gap the plugs from Larry, in addition to learning more about my supercub.

I'll let you know how this all goes.

WindOnHisNose said:

but that he didn't recommend this. Please forgive my interpretation of his words, but it was my impression that he felt the engineering of the housing upon which the right mag is mounted is not as supportive as the left, and he worried that it might cause problems (again, my interpretation of what he said). Hence, I decided not to install an redundant impulse coupler on the right.

I am feeling really good about the decision to pull BOTH mags and to replace the plugs. Plus, I learned how to gap the plugs from Larry, in addition to learning more about my supercub.

I'll let you know how this all goes.

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Hmmm

Thought there was just a spacer on the mag without the impulse?

Scruffdog,

Cold... Try LOTS of priming.
My old engine would start good on 2-3 shots, but the newie takes 4-5.
Beautiful morn. here again, I think I'll go give my primer a few shots later on.

You know, it was my impression that the spacer wasn't the problem, but rather that the engine housing itself wasn't as sturdy as where the left mag attaches.

How many of you have dual impulse couplers?

Randy

I do.

WindOnHisNose said:

You know, it was my impression that the spacer wasn't the problem, but rather that the engine housing itself wasn't as sturdy as where the left mag attaches.

How many of you have dual impulse couplers?

Randy

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You have to also pull the mounting studs out without Fu@&$/g up and add replace with longer ones, that may be what they were referring to....

When I replaced the mags with slicks on my c-90 they both came with impulse couplings. I've seen a bunch of guy's try to hand prop a SC with both mags on only to have it kick back, Cub Amigo said to start on impulse mag and made a big differance with no kick back.

Randy

Sounds like you are on the right track. I would say you should be fine with only one impulse mag. The impulse mechanism is only used to start. Your key start switch locks out out the right mag on start so if it had an impulse it would not be activated. The only time it might come into play would be if you chose to handprop on the right mag. Overall not very likely. Don't forget that your plug wires can age and get high resistance as well. How old is your harness? Just another thing to consider.

See you soon.

Bill

What was the gap on your plugs? I wouldn't go through the trouble and expense to install an impulse coupling on the right mag. I haven't seen a Slick impulse coupling fail. You would have to replace the mag, and add a spacer and as Mike said the longer studs. Be interested to know if the E gap was off much with 450 hrs. I assume they will check the carbon brush and cam service bulletins.

Steve:

Do you think the Slicks should be replaced at 800 hrs? My 0-360 is now at 950 on original mags. We checked e gap at 800 and it was off a bit. I have been left in the cold, literally, with crapped out Slick mags, and should probably replace them at annual. Who has the best pricing now? Seems like the Slick pricing has really gone up in the past 3 years.

JIm

Jim, There is an inexpensive E gap tool that should take care of your problem. Adjust the E gap and keep going. No need to replace. Champion paid a lot of money for Slick and raised the prices considerably to make it back quicker.

Here is a link that explains e gap and shows the Slick tool.
http://www.sacskyranch.com/egap.htm

The mags were returned to service and were rebuilt. They apparently found the eGap a problem on the left mag, and it was explained to me that this was just due to wear. The brushes were full of carbon and worn, also. While they were at it they replaced the spring on the impulse coupler.

Larry Cassem replaced the mags yesterday and I had the chance to start the engine and run it up, but it was low IFR and I couldn't fly the aircraft, and today the wind is howling, so it looks doubtful I can fly it today. It ran nicely on the ramp, though.

Bill Rusk, I asked them to look over the harness and wires and they looked good, so I left them alone. That is something I am going to consider, though, at the annual due in November.

Steve Pierce, the gaps on the plugs were a little wide (0.22), but Larry felt that wasn't the problem. I regapped the new plugs.

I'll give an update when I can run the engine up to temp and shut it down and restart! Thanks for all the suggestions and input, you fellas. As usual, there is a wealth of information here, a real pleasure to be able to access you all.

Randy

I took the supercub out for a flight Sunday and omg did it start easily, both cold AND HOT!!! Really satisfied with the outcome following rebuilding the mags and replacing the plugs.

I am keeping a couple of the plugs (with low resistance) and will vacuum seal them and keep them with my repair kit in the aircraft.

Many thanks to all who threw in your two cents worth. Again, a great learning experience.

Oh, btw, I believe Steve Lewis was told that my PA18 is not approved for having two impulse couplers. I had already decided not to add the second. Not sure why it apparently isn't approved for that.

Thanks, again.

Randy

P.S. For those who haven't visited the Aeromedical Forum string, please take a look at my recent posting regarding new cardiopulmonary resuscitation recommendations...pretty important changes.

At the Slick booth at Oshkosh this year they had one of there top techs that had written the 500hr inspection how to letter show anybody who had 30 min to spare how to take the mags apart, including removing the impulse, and center electrode to check the spring inside, and how to remove the carbon from the contacts and check the e-gap with the little tool that they let you keep for free and then how to reassemble. He also said that if you needed anything more then new points and the center electrode and the spring that it didn't pay to overhaul them, a new mag was under 900 bucks and that the parts to rebuild would cost over a 1000.00 without labor.

Glenn

That was Joe Logie.

Aero Accessories has Slick parts a lot cheaper than OEM. I can't remember what normal payback is when you buy a company but when Champion bought Slick it was gonna be 20 plus years. They decided to almost double the prices.

A few things...

Shut down with the mixture, mags hot. On the hot start do NOT EVER push the mixture in. Push the throttle forward about half way and back to the stop, mag (or magS if dual impulse) hot, turn it about 3 blades and it will sputter, push the mixture full rich quickly only when it begins to fire.

Nothing wrong with Slicks, just clean and reset the points every 400-500 hours.

There is a Lycoming SB or SL to convert to dual impulse. You put in longer studs and add the adapter, not a big deal. I have converted mine, but I hand prop. If I had a starter I would not bother. If you have a key start and single impulse make damn sure the jumper is installed on the switch, this is a common mistake when converting to a key.

If you need new plugs and fly a lot, concider fine wires. I've been having very good luck with them in flat and round motors.

Read all the posts on hot start problems--lots of good info. My problem is similar. Cub(0320 A2B 160) usually starts fine cold but sometimes is even balky when cold. If we stop just briefly(like 5 or 10 minutes to refuel) it usually starts right up. However, if the engine is shut down for an hour or so nothing seems to word--just wont start. Left me stranded in the bush once and almost delt my son the same fate. After it left me stranded and I returned next day we jumped the low battery and it fired up immediately. Since almost all our flying is off airport to fishing and hunting spots I need this problem GONE!!!! From what others are saying sounds like a mag or plug problem. Annual is due next month so we will concentrate on those. Any other suggestions would be greatly appreciated.

We just went through this same problem with the Crimson Cub. It was exactly as Randy and Btoneyak described. The slick mags had 1000 hrs of service total time (rebuilt at 500 hrs) and would cold start fine but extremely difficult to hot start. We upgraded with the "E" Mags and problem solved. We are experimental though. It starts fast cold or hot or inbetween, doesn't matter. So happy with the outcome. We cleaned and gapped the plugs before we pulled the old mags hoping this would help but there was no noticeable improvement until we pulled the slicks and replaced them.

btonyak

Type mags? Last time removed for service?

A defective Coil will provide a weak spark when hot.

You may want to consider 2 Impulse coupled mags

or "SlickStart".

Flight schools encounter similar troubles with

a variety of different pilots using ? techniques.

Aircraft that won't start can be VERY costly.

aceherks said:

This what I was taught to do: Cold Starts. Shut down--full rich then left hand turn off both mags and right hand full throttle.

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Is this the way you shut down? Please give some details.

My 0-360 hot start is mixture in and throttle full CLOSED, this is the easiest way to start it for me.

Doug

Thank you for your post. Does your procedure change at all for hand proping?

WhiskeyMike said:

SuperCub MD said:

A few things...

Shut down with the mixture, mags hot. On the hot start do NOT EVER push the mixture in. Push the throttle forward about half way and back to the stop, mag (or magS if dual impulse) hot, turn it about 3 blades and it will sputter, push the mixture full rich quickly only when it begins to fire.

I'm with SuperCub MD. Won't fix the mags but has ALWAYS worked for me in all of the O-360's without fail. Many of which were hand prop only. 3 blades and Off you go.

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