O-360-a4a won't start

simtech

simtech

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Simtech
I started another thread about my endeavor but figured it might be better suited here. Went on a trip yesterday. 1.2 hour flight. Landed and two hours later plane wouldn't start. It was around 65 degree yesterday if that matters. But back at the airport..hit the starter and nothing but a spinning prop. Would not start or even try to. Primed it, cold start procedure, hot start procedure, flooded procedure, hooked up the start cart and still no start. About 45 minutes go by in all. So I had a buddy fly down and pick us up. Plane is still there 100 miles away. Last time it did this I was at the home drome and I didnt pre heat and it was 33 out. So I understood that one. I checked the p leads and they were tight. Now I have to wait till Monday for a mech to see it. Unless I go down today and try it on a whim..but that's a long drive.
 
Failed impulse coupler left mag.
 
Could you hear the impulse coupler click? Did you try disconnecting the P-leads from the mags?
 
Yes I could hear the click. And nope didn't disconnect anything. I found a loose connection on the ignition switch but once tightened up it still did not help. What sucks is my plane is 100 miles away! Ugh...frustrating
 
P leads what supply the ground?? What does disconnecting them say if it started or didn't?
 
simtech said:
P leads what supply the ground?? What does disconnecting them say if it started or didn't?
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If you disconnect the P-leads, you take the switch and a short in the wire out of the equation. If the mag is good, it will spark with the p-lead disconnected. There are switches that are known points of failure for this symptom.

Stuff like this is why I carry a tool box.
 
Henning said:
If you disconnect the P-leads, you take the switch and a short in the wire out of the equation. If the mag is good, it will spark with the p-lead disconnected. There are switches that are known points of failure for this symptom.
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Oh I got you. It creates the hot p lead that causes spark with the switch turned off?? Makes sense. Well I do have the switch with the ad. So I could disconnect it and if it starts fly it home or is that still a no go situation?
 
simtech said:
Oh I got you. It creates the hot p lead that causes spark with the switch turned off?? Makes sense. Well I do have the switch with the ad. So I could disconnect it and if it starts fly it home or is that still a no go situation?
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Kind of, other way around though, a minor, but critical distinction. The magneto is always hot by the nature of its design. The p-lead creates a ground at the points which prevents a spark from forming by creating a permanent 'points closed' condition. As long as the magneto is spinning, it is creating a current. With the switch closed the current is shunted to ground. With the switch open, the points create a build and collapse in the magnetic field, and this collapse is what creates the spark that goes through the rotor and to your plug.

Yes, if you secure the p-leads off the mags, if the switch is the point of failure, it will fly home safely.
 
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A warm Cherokee is easy to flood. Don't prime after just an hour stop.

A few (Oh the humanity!!) stokes of the throttle during starter engage/"L" mag and it would have started on the first blade.
 
Our Cessna floods very easily too if the engine or the ambient temp is warm. Usually, though, I can get it started by pulling the mixture all the way out and cranking. If the engine is warm, I don't use prime at all.
 
I'm gonna try it again today if the weather holds to get there and back. Say I get far enough along that I pull the p leads..would I pull both or just the left? And i assue I do it at the mag..duh I know but thought I'd ask anyway.haha
 
Disconnecting the left (deep) mag 'should' suffice, however if it fails to drop on a right mag check, you need to disconnect both.
 
simtech said:
I'm gonna try it again today if the weather holds to get there and back. Say I get far enough along that I pull the p leads..would I pull both or just the left? And i assue I do it at the mag..duh I know but thought I'd ask anyway.haha
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Take a left mag with you.
 
We take care of a flight school, they have proven the 0-360 can be flooded, all 6 of them on a weekly basis.

Pull the lower plugs and clean or install another set.
 
I don't have a spare mag lying around. We didn't go today but we are making the drive in the morning to it. We will see what happens. I bet it fires right up:mad: but after landing for a few hours countless other times it has never done this.
 
simtech said:
I don't have a spare mag lying around. We didn't go today but we are making the drive in the morning to it. We will see what happens. I bet it fires right up:mad: but after landing for a few hours countless other times it has never done this.
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You can hope, it's definitely one of the possible outcomes with the same odds as any other at this point.
 
simtech said:
I don't have a spare mag lying around. We didn't go today but we are making the drive in the morning to it. We will see what happens. I bet it fires right up:mad: but after landing for a few hours countless other times it has never done this.
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next time....no more than 2 shots of prime for the hot start. :nono:
 
An engine requires fuel in approximately the right proportion to the air, spark at about the right time, and compression. Period.

Before you go around trying a bunch of random stuff, figure out which one of the above is missing. It's not likely to be compression. That leaves fuel and spark.

Fuel - could be too much or too little. If there was too much the other day, it's probably gone by now - try a normal cold start. That is the first best bet.

No start? Pull a plug (preferably from the mag with the impulse) - smell for fuel (back to fuel in a moment). Check for fouling (clean as necessary). Turn the engine over with the outside of the plug touching the engine. Get a good hot spark when the mag clicks? Yes - go back to fuel. No - spark is the problem. Could be the impulse has failed (less likely if you heard it click), could be the P lead is grounded somewhere - try disconnecting. (Spark timing is not likely to be the problem if it ran when you shut it down). Still no spark? Youse gots a bad mag. Get it fixed. Note: At temperatures below freezing you can fire once or twice and ice the plugs - the solution is to warm them up.

But if you got a spark, then you probably have too much or too little fuel. What did the plug smell like? Strong fuel odor - you are flooded. Crank with fuel shut off. No fuel odor? Try turning the fuel selector to a tank that actually has fuel in it :). Try some ether (starting fluid). Kick and quit? Obstruction in the fuel system. Get it fixed. Starts and runs? Give it a couple of minutes and fly home.

Essential tools - plug socket and torque wrench, a wrench to remove the spark plug lead, and a can of starting fluid.

If you hadn't been hooked to a booster, I would have suggested bringing a battery charger too since your battery would be dead by now.
 
A weak spark can make the plug fire outside the cylinder in ambient air, but it can fail under compression. A better test is to take the lead and hold it near the rocker box screws or some convenient ground point, and click the mag. The spark should easily jump a half inch.

If mags don't get regular maintenance, they can get weak. The points erode, increasing the gap and throwing the internal E-gap off. Anything but the proper E-gap weakens the spark. If a mechanic has to retard the mag timing more that a couple of degrees, he should be suspicious. The points cam can wear, degreasing the gap, which retards the mag timing and also throws the internal E-gap off. The distributor bearings and electrodes can wear out. The condenser can develop internal electrical leakage. Lots of stuff that needs periodic checks.

Dan
 
Drove down today to look at plane. I tried to start it and not even a hiccup. So I disconnected the p leads and still nothing. Sooooo...took it over to maintenance confirmed no spark. They hooked up the mags to some beepy red light green light thing and we found the left mag bad. The light for the left mag would flicker ever so slightly but that was it. So they are going to replace the points, capacitor, and re time both mags. I'm still surprised if it failed in flight why I got no indication. Unless it was one of those once it fired it was good but on restart just not enough. So 6 hours in a car today round trip..gotta love it!
 
Once you are down to cruise power and if you're in any turbulence, you can lose a mag and not notice.
 
simtech said:
...I'm still surprised if it failed in flight why I got no indication. Unless it was one of those once it fired it was good but on restart just not enough...
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You probably did lose some rpm running on one mag but didn't notice it. You've still got one good mag but it's the RIGHT one which has no impulse coupler and is fixed at 25 degrees advance (which is way too much at cranking rpm) It could in fact fire and cause a kickback which is bad for starter clutches and vacuum pumps so the RIGHT mag is disabled by the ignition switch when in the START position to prevent that. When you disconnected the p-leads you disabled that safety feature so were in danger of a kickback at that time.
 
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You can hand start without an impulse, but not recommended unless in serious trouble. You can pull through a collapse a lot faster than a starter will spin it (although I wonder if a Skytec may do it) and you can pop one up. However... kickback becomes a greater risk if you have just not quite enough speed through the pull.
 
Henning said:
Once you are down to cruise power and if you're in any turbulence, you can lose a mag and not notice.
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Got it. I was always under the impression a bad mag in flight would cause roughness..But really why..during runup its not rough just an rpm drop. You learn stuff everyday. We were in cruise but it was dead calm. I joked with my wife that it felt like we had autopilot., trimmed so perfect I didn't have to touch the controls hardly at all during the hour cruise.

I did notice one time during the flight the fuel pressure dropped slightly below 5. I watched it for a second and it crept right back up to just above 5. I know that's not mag related. But sure did make me watch it more. POH says normal range is 1 to 7...really 1psi..I don't think so, the pump would be on below 4!

So hopefully I can get back down there maybe Friday and pick it up. Might take another hour flight south and hit up gulf shores for the long...COLD..weekend.
 
simtech said:
Got it. I was always under the impression a bad mag in flight would cause roughness..But really why..during runup its not rough just an rpm drop. You learn stuff everyday. We were in cruise but it was dead calm. I joked with my wife that it felt like we had autopilot., trimmed so perfect I didn't have to touch the controls hardly at all during the hour cruise.

I did notice one time during the flight the fuel pressure dropped slightly below 5. I watched it for a second and it crept right back up to just above 5. I know that's not mag related. But sure did make me watch it more. POH says normal range is 1 to 7...really 1psi..I don't think so, the pump would be on below 4!

So hopefully I can get back down there maybe Friday and pick it up. Might take another hour flight south and hit up gulf shores for the long...COLD..weekend.
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Remember, a carburetor does not require fuel pressure, a carb just requires fuel to flow to it in the same volume it is being consumed. The piston coming down on the intake stroke provides vacuum, and vacuum makes it work. Think about your lawn mower. Your fuel tank is inches above the carb, you don't even have 1/4psi fuel pressure.

If you want a gauge that is indicative of the health of the fuel delivery system, get a proper fuel flow/totalizer, they're the best thing in a plane anyway.
 
simtech said:
Got it. I was always under the impression a bad mag in flight would cause roughness..But really why..during runup its not rough just an rpm drop. You learn stuff everyday.
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I've had the same thing happen (Lyc O-360A1A), crapped out somewhere between Billings and Hamilton, Montana. First clue there was something wrong was when I attempted to restart it after refueling.
 
simtech said:
So 6 hours in a car today round trip..gotta love it!
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Just be glad you don't own a boat...

I think I made 5, 6 hour round trips for a boat purchase. Once to see the boat. Another to buy it and do paperwork. Another to pick up the trailer. Another to go pick up the boat, but it wouldn't start. Yet another to finally pick up the boat.

Now I will be making another on Sunday to drop the boat off at a shop, as no decent marine mechanics around here. It was a bit of a project and I just don't have time to do all the work it needs.
 
Shop called today and my plane is fixed. Said it started up on first spin. Yes cause it hasn't done that since I owned it. But from the sounds of if they ended up overhauling it. The gears were stripped and had gear dust over everything. So they replaced the gears, points, capacitor, distributor block, and something else I cant remember. Then they timed both mags and all is good they say. So Friday we will fly down and pick it.

Maintenance flight....take it around the pattern a few times and land and check under the cowling? Or just check under it from the start and then if it starts we know its good and head home? First time to fly a plane after maintenance.
 
simtech said:
Shop called today and my plane is fixed. Said it started up on first spin. Yes cause it hasn't done that since I owned it. But from the sounds of if they ended up overhauling it. The gears were stripped and had gear dust over everything. So they replaced the gears, points, capacitor, distributor block, and something else I cant remember. Then they timed both mags and all is good they say. So Friday we will fly down and pick it.

Maintenance flight....take it around the pattern a few times and land and check under the cowling? Or just check under it from the start and then if it starts we know its good and head home? First time to fly a plane after maintenance.
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I usually ask them to leave the cowl off or a light button, I do a look over of the work, safety wiring... test run/leak check on the ramp, if it's all good, close it up and go. If it is bad terrain surrounding you could consider climbing out over the airport a few thousand feet, that'll give anything that's going to shake loose a chance to do so. Hit cruise altitude if everything is good, turn for home.
 
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Good question. I always assume the role of test pilot after maintenance. Always have. All that means is I won't take a passenger until i know it's running the way it's supposed to.

BTW, many shops turn the fuel off as a rule when they bring a plane in for service. Make sure to check your fuel valve if that isn't already a part of your pre-flight routine.
 
Stewartb said:
Good question. I always assume the role of test pilot after maintenance. Always have. All that means is I won't take a passenger until i know it's running the way it's supposed to.

BTW, many shops turn the fuel off as a rule when they bring a plane in for service. Make sure to check your fuel valve if that isn't already a part of your pre-flight routine.
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Yep, post maint flight is either solo or with the mechanic.
 
Yeah my wife is coming along for the ride back. So Ill go out solo for a bit before we take off back home.
 
simtech said:
Drove down today to look at plane. I tried to start it and not even a hiccup. So I disconnected the p leads and still nothing. Sooooo...took it over to maintenance confirmed no spark. They hooked up the mags to some beepy red light green light thing and we found the left mag bad. The light for the left mag would flicker ever so slightly but that was it. So they are going to replace the points, capacitor, and re time both mags. I'm still surprised if it failed in flight why I got no indication. Unless it was one of those once it fired it was good but on restart just not enough. So 6 hours in a car today round trip..gotta love it!
Click to expand...

Where's my prize for the correct diagnosis?
 
I wouldn't take the cowling back off unless it was a very simple job. I would do a thorough preflight, then fly the pattern as others have recommended. If everything was okay, head for home. That is my normal procedure after any maintenance or an annual.
 
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