Mag problems

[Michael]

I posted alittle about this from my return trip out of Gastons, But thought I would ask here for more information.
I have an O&VO-360 SER LYCOMING in my M20C. Here is what we know so far...As the outside air temps have gotten hotter (118 degrees in Arizona) The oil temps have been running on the hot side. I have managed to redline the temps twice. Oil pressure dropped both times but were within green and the oil cooled down after leveling out the climb.
I have noticed that after an oil change, within 5 hours the oil is getting dark. This could be from the heat? or compression?.
Now the new problem...could be related???
While trying to depart Sante Fe, NM. durring my runup, i switched to the left mag and the engine started poping. I tried to run the engine exsessivly lean to clean up any buildup without any luck. So a mechanic was called in. He cleaned the plugs which were extreemly dirty and fouled. and reinstalled them, After the work was performed, the engine seemed fine. During runup, the mag check looked good. Problem solved i thought. However, after a short flight to Arizona, the left mag was producing the same "poping" results. My mechanic is going to take a look at it, but says it sounds lie the plugs are fouled again. I just do not understand how it could be possible in a 3 hour period to foul the plugs that bad. I ran the engine just as the POH says to. even lean it out durring taxi. My guess is there is something else at play here.
Does anyone have any ideas?

Michael

 

[Let'sgoflying!]

is it consuming oil? it will be interesting to see the plugs again.

 

[Anthony]

Mike,

Is their a pattern on which cylinders foul the plugs or are they all getting fouled?

 

[Michael]

is it consuming oil? it will be interesting to see the plugs again.

Not really..about a 1/2 quart every 10 hours.

Is their a pattern on which cylinders foul the plugs or are they all getting fouled?

I dont know yet. I will find out as soon as the mech takes them out. What would that mean if only a few plugs were fouling?

Michael

 

[zephyr]

"Bad" plugs that misfire intermittently will not stay as clean as plugs that are working properly. I'd try 3 REM-37BY plugs in the bottom provided you have the compatible small "B" nut harness. The oil turning dark quickly is an indication of blow by into the crankcase but burning a quart in 5 hours this should be OK. Charlie Melot Zephyr Aircraft Engines

 

[poadeleted20]

Were the plugs fouled with lead, carbon or oil? Many different possible causes based on what was happening. However, oil does darken with use, and some oils (e.g., Exxon Elite) darken faster than others, although this means little as regards its lubricity. Do you have a spin-on filter or just a screen? That can make a difference in how fast it darkens. At any rate, you want to keep your oil temps in the 160-200 range for optimum oil/engine life, and you don't want it over 220F if you can avoid it, even if your redline is 240F. What to do?

Some folks in the southwest find they need bigger-than-stock oil coolers, especially in the hot summers. Check with the Mooney gurus about STC's for a larger oil cooler. Also, your engine may be running higher-than-desirable CHT's, which drive up oil temps. What are your CHT's running? How's your baffling? Are your baffle seals tight and cut properly to fit around the ridges and bumps inside the cowling? Talk to a Mooney expert on these issues.

 

[FLYJAGUAR]

My understanding of the dark oil is, that it is -?- very common in lycoming to be dark black after just a few hours of operation. Even in the 540.
The mag problem has been addressed very well, but give the condenser a change. They are cheap enough to try a replacement. And check internal timing of both mags.

 

[bbchien]

My understanding of the dark oil is, that it is -?- very common in lycoming to be dark black after just a few hours of operation. Even in the 540.
The mag problem has been addressed very well, but give the condenser a change. They are cheap enough to try a replacement. And check internal timing of both mags.

...and if that fails, go to fine wire plugs at $60 each, on the bottom. They are VERY VERY difficult to foul (they can be fouled, for sure, though)...

 

[PoAdeleted5]

The 37BY plugs are much better at resisting fouling than the fine-wires and they cost no more than regular plugs.

Before my overhaul, my O360 would foul fine wires easily. I put a set of Unison REM37BY's in the bottom and they stayed clean. The fine wires are still on the shelf in my garage.

118 degrees f ambient, tightly cowled mooney, it's probably just going to get hot. Step climbing and cruise climbs are probably all that's going to keep you cool.

How are the CHT's?

 

[Michael]

118 degrees f ambient, tightly cowled mooney, it's probably just going to get hot. Step climbing and cruise climbs are probably all that's going to keep you cool.
How are the CHT's?

I can keep the CHT temps under controll with mixture. they dont get too hot. Its the oil temps thats been the problem..I found out yesterday, my mechanic replaced the #2? PLUG, said it was flouled again, and he said that possibly the mechanic out in sante fe didnt clean out the housing very thougholy, which just deposited more carbon onto the plug.
So good news is, I think, i am just getting away with a cleaning.
Ill let ya all know how it works out.

Michael

 

[Tom-D]

The mag problem has been addressed very well, but give the condenser a change. They are cheap enough to try a replacement. And check internal timing of both mags.

Are you aware that checking/changing the internal timing of a magneto requires some very special tooling/fixtures? and how many A&Ps will even open a mag, and repair anything?

 

[Let'sgoflying!]

and how many A&Ps will even open a mag, and repair anything?

And this is a tragedy. I suppose its linked to what is easy, most lucrative, least liability for the A&P - but it is a sad loss of expertise. A&P shouldn't mean 'parts swapper'.
The parts people themselves do not promote repairing either. Everything is disposable in their view, 'you need a new one'.

 

[FLYJAGUAR]

Are you aware that checking/changing the internal timing of a magneto requires some very special tooling/fixtures? and how many A&Ps will even open a mag, and repair anything?

If you take your aircraft to an A&P who does not know how to, or have the tools to set the internal timing on a mag, find an A&P with a license!!!!!!

 

[Tom-D]

How many A&Ps do you know who have a overhaul manual for a Slick/Unison mag?

The tools and test equipment to repair and return to service a single Bendix mag are well over 5k.

Yes I know many A&Ps dissasemble mags, but few do it properly.

 

[Stache]

"I have noticed that after an oil change, within 5 hours the oil is getting dark. This could be from the heat? or compression?."



The dark oil is from combustion, a little carbon get past the rings and discolors the oil this is normal. The oil filter cleans the big stuff so it okay. However if the oil is real hot it will coke and cause the oil to turn even darker.



For the foul the plugs, there are several checks that can and should be performed.

First let me explain what the deposits are on the plugs. Aviation fuel has lead in it for many reasons, but I will not go into it now, when combustion happens the lead is atomized and if the combustion camber is not hot enough the lead forms little balls. It is these little balls of lead you see on your plugs. As long a the fuel/air mixture is leaned properly the cylinder stays hot enough for the lead to be atomized and flow out through the exhaust pipe as designed. If the cylinder is cool the balls form causing fouled plugs.


As mentioned there is several things to check. One, is using a high-tension tester check the plug wire for resistance they should be with in limits as stated in the maintenance manual. Two, check the plugs them self in a plug tester box to make sure they are firing under compression some don’t very well even new ones. And third, check the magnetos. Magnetos will work fine at lower speeds and at high speed the points will float causing miss fires to the plugs. The only way to check the mags is to pull them off and send to a Repair Station and have them tested on the bench. Testing is very cheap. I have seen bad points show up at high speed on the bench many times and a A&P does not have the equipment to perform this test. At he repair station the shop may check the coil in the mags, some are weak coil and he same for the internal magnet as it will cause the same effect.



Just one A&P/IA opinion.


Stache

 

[gismo]

I can keep the CHT temps under controll with mixture. they dont get too hot. Its the oil temps thats been the problem.

Excessively high oil temps will cause the oil to darken rapidly as will blowby. BTW excessive blowby causes high oil temps! If you cannot get the oil temps down, a semi-synthetic might be desireable from an engine longevity perspective.

 

[Tom-D]

And this is a tragedy. I suppose its linked to what is easy, most lucrative, least liability for the A&P - but it is a sad loss of expertise. A&P shouldn't mean 'parts swapper'.
The parts people themselves do not promote repairing either. Everything is disposable in their view, 'you need a new one'.

On the mags that your every day common flying machines use, the sum of all the repair parts are more than the cost of a new mag. So besides the libility thing, it is not cost effective.

But if you have an old Bendix DF7 mag. You couldn't buy a new one for all the tea in china. So, you find an old mech that has the parts in his 40 year box. and see if they will "repair as required" to return to service

 

[PoAdeleted5]

I can keep the CHT temps under controll with mixture. they dont get too hot. Its the oil temps thats been the problem..Michael

Check your maintenance logs and see if you can find the last time your oil cooler was off and sent out for a thorough cleaning.

Most of the cooler makers recommend about 500 hours, pull it off, clean it and reinstall. Some mechanics just rinse them with solvent, but that may not clean out all the goo and varnish from the inside. A place like Pacific Oil coolers can overhaul yours to like new condition for pretty reasonable money. On my Cherokee, a brand new oil cooler wasn't that expensive, so I just replaced the 40 year old Harrison cooler with a brand new Aero Classics. Even in it hot weather and climbing, I've not seen more than 200 degrees since the engine overhaul.

At the very least, get a look at it and see if the fins are clogged up with bugs and dirt and stuff. Clean em out carefully, make sure any duct work or scat tubing is in good shape so that the cooler gets a good strong blast of air.

Then there's always the vernatherm, or viscosity valve if your engine is old enough and not converted to the thermostatic vernatherm valve (like my old Cherokee). If it isn't working correctly, it may be letting to much oil bypass the cooler.

If the problem is blow-by, there's not much you can do about it except repair or replace the offending cylinder(s).

 

[Let'sgoflying!]

On the mags that your every day common flying machines use, the sum of all the repair parts are more than the cost of a new mag.

That's what I mean by the companies not helping people to repair them anymore, they are pushing for replace the whole thing. It's getting to be a lost skill.

So besides the libility thing, it is not cost effective.

try Spruce, Tom - I recently bought a repair kit with everything I needed for a Bendix - it was under $70. They are going new for $1300.00 although I spose you could buy a reman for less.
Certainly there is a point where they are beyond economic repair... although I did have a cracked case and my local mech *gave* me a spare he had.

 

[Tom-D]

That's what I mean by the companies not helping people to repair them anymore, they are pushing for replace the whole thing. It's getting to be a lost skill.



try Spruce, Tom - I recently bought a repair kit with everything I needed for a Bendix - it was under $70. They are going new for $1300.00 although I spose you could buy a reman for less.
Certainly there is a point where they are beyond economic repair... although I did have a cracked case and my local mech *gave* me a spare he had.

What was in your repair kit?

The coil alone is a $100 +-
Distriburator block was 150 last I checked.
I don't see a price or listing for a magnet rotor. Last I bought I felt ripped off.

 

[wsuffa]

What was in your repair kit?

The coil alone is a $100 +-
Distriburator block was 150 last I checked.
I don't see a price or listing for a magnet rotor. Last I bought I felt ripped off.

Just got out of annual. IA had to replace the distributor block and rotors. (see picture)

He never would have opened it, except that we did the impulse AD since it will be due in less than 100 hours.

The dist block alone was well over $150.