When my plane is running I get a lot of ignition static through the headphones. I thought it was just old wires but when I do a Mag check everything goes quiet on one mag. They both have RPM drop and seem to be working fine but one is causing ignition noise. Any idea what is causing it and how do I correct it? Thanks

Jerry

Bad ignition harness on the mag that makes noise, not the quiet one.............

d

I also have some vibration. You can't feel it much at idle or runup but when the engine is under a load at about 2200 RPM it vibrates. The higher the RPM the smoother it gets. At first I was thinking that the Prop needed to be balanced but now I am thinking that if one cylinder isn't pulling as hard as the others it might be causing the vibration. Seems like if the prop was out of balance it would get worse at higher RPM's. Hopefully getting this fixed will take care of two issues.

Another question, Are the Spark plug wires shielded with metal? I was thinking of taking off the cowl and running it at night. If I have a spark jumping it would be easy to find, but if the wires have a grounded shield I wouldn't be able to see the problem because the spark would be jumping inside the shield. Make sense? Then I would just need to start replacing stuff starting with P leads and plug wires. Could possible have a sticky valve since it sat so long but I don't think that is the problem.

We use to put a condenser on the wire to the distributer in cars to keep the radios quiet. I see Aircraft Spruce sells a "Noise Filter" that looks like a really expensive condenser. I can try that as a last resort but I would rather fix the problem than quiet it. Thanks for your input.

Jerry

Nothing much to do with the static, but the roughness under a load could be bad points & condensor in the mag, bad plugs, or a bad harness. Try Left mag & right mag at cruise power & full power to isolate it. When the mag spark can't overcome the resistance in the plug, the plug needs to be replaced- even if the center electrode shows very little wear. You can try replacing the resistor inside the plug, IF you can find a resistor. IMHO this bad resistor thing happens sooner with Slick mags than with Bendix- I'm convinced that Bendix mags throw a hotter spark. I found that with Slicks you're doing well to get 500 hours out of a set of plugs.

Eric

Define "rough". Every O-360 I've met shakes a bit. Some rpms are always worse than others--so you just have to find the rpm where that engine is happiest.

Unless of course, you're talking ACTUALLY rough, as opposed to "just a little rougher".

The best thing I did for my O-360 was stick an MT prop on the front of it. That made a not real smooth engine smooth as glass.

MTV

MTV, if I let go of the yokes they bounce pretty good at some RPM's. It isn't like it will shake the plane apart or anything but sure not as smooth as the old O-300.

I will try what Hotrod said. I will get some load on it and then switch mags back and forth. If the roughness is only on the one making the noise, I will know it is an ignition problem on that mag or wires. Should be a lot worse if only three cylinders are firing.

If it viberates during both checks, it is probably my prop needs to be balanced or could possibly a sticky valve. Or, like you said, might just be the way the engine is. I would love an MT Prop or the 80" Hotprop but first things first.

Jerry

If you're expecting an O-360 to be as smooth as an O-300, you better start thinking MT prop.... Otherwise, there will never be a comparison. The O-360 has two less pistons and rods, and the pistons are MUCH larger. Harder to balance.

MTV

I agree with most of what has been said above. I recently had an ignition-related vibration, and after some troubleshooting on the plugs and harness, it was finally solved by replacing the points and condenser in the offending mag. Your timing may be off on the one mag too.

I've also seen some healthy vibration from an improperly indexed prop (C-145) but I don't know if that's relevant to the O-360 as much. Yours definitely sounds ignition related if you can smooth it out by switching off the offending mag.

As for ignition-related noise in the intercom, check your ignition switch leads and connections behind the panel. The P-lead on that mag might be done too.

I ran it pretty hard on the ground yesterday and switched the mags back and forth. I really couldn't tell any difference. The plane hadn't been annualed since 84 and it looks like all the wirings is original (50 years old) so I will just start replacing all the ignition stuff as I go.

As far as I know the plane has only flown about 10 hrs since the annual in 84. I am going to get some hrs on it and do an oil test. I hope it isn't a cam since it sat so long. I know a guy here that can do a dynamic balance on the prop so I will probably do that just to make sure it isn't the prop.

This economy has just kicked my butt so everything has to wait till money comes in. At least the plane is useable now and someday I will have a nice 175/180.

Jaerl wrote:I ran it pretty hard on the ground yesterday and switched the mags back and forth. I really couldn't tell any difference. The plane hadn't been annualed since 84 and it looks like all the wirings is original (50 years old) so I will just start replacing all the ignition stuff as I go.

As far as I know the plane has only flown about 10 hrs since the last annual. I am going to get some hrs on it and do an oil test. I hope it isn't a cam since it sat so long. I know a guy here that can do a dynamic balance on the prop so I will probably do that just to make sure it isn't the prop.

This economy has just kicked my butt so everything has to wait till money comes in. At least the plane is useable now and someday I will have a nice 175/180.

So the plane was annualed before you started to fly it recently?

The plane came with a new BS Annual, it has a signature but the annual was BS. It is still in annual so it is legal to fly more or less and I'm not saying I'm not, not flying it.

A good trustworthy AP/IA is worth his weight in gold. Find one.

The rip off or stupid ones are not worth a 22LR bullet to shoot them in the big tow. Avoid at all cost.

The plane has actually had 10K and 6 months work done to it under supervision of the FAA Inspector in SLC. My mech is pretty good and one of the most honest people I have ever met. Has you mech ever just charged you $20 to grease your wheel bearings because it only took him 20 minutes?

His family has been flying and working on planes forever and they actually built U77. His grandfather's pilots license was signed off by one of the Wright Brothers. When I have a problem the whole family chimes in and I have 100's of years of experiance here. I have had cheaper mechanics work on my planes and it always cost me a lot more. Plus, after this plane he has taken pity on me and lets me do some grunt work to save money. I think I will stick with my mechanic.

Jerry

Not to stir up anything here! But when plane shopping about 3 years ago, I went to look at a 182 up in Weiser, Id. The 182 was supposedly fresh out of an extensive annual. But close inspection revealed CRACKED seat rails and very dirty carpet that didn't look like it was taken out of the plane the access the floor inspection plates. We pretty much stopped right there and didn't bother looking any further. Who knows what else was wrong, but we didn't want to waste anymore of our time. Unbelievable!! The price was right, but diffidently too good to be true!!! Good thing my mechanic and I were not suckers!

The funny part was lessening to the two guys showing us the plane talk about how proud they were about not finding anything wrong with the plane during the annual, what an awesome the plane was, so on and so on.

Yea, Sucker is probably the best word to describe me in this deal. What I bought was a project plane and a bag of promises from an airport Manager/Aircraft Dealer. Problem is the bag of promises were just that. All the new parts I was shown never showed up with the plane (including the STOL Kit) . When someone tells you they did the AD on Oil Pump gears and actually notes it in the AD list, do you pull the oil pump out to check? Well neither did I.

They say knowlege is power and when it comes to planes I have none of either. That is why I am here bugging you guys. But the good part is my plane is looking great!