M20J won't start and my mechanic is stumped

[pfactor]

When I ordered the factory remanufactured engine in 2007, I don't think I was given a choice about what type of mags to get. So if Lycoming normally ships with Slick mags, that's what I've got. I'm not actually sure but I'll find out when I talk to my mechanic tomorrow.

Based on this thread, here's my current plan.

1) Change out the spark plugs for Tempest ones. I haven't decided on massive or fine wire yet.
2) Send the mags back to the overhaul shop for inspection/repair. Test with a known good mag while waiting for that.
3) See if http://www.mooney.com/en/si/M20-59A.pdf was previously done, and if so undo it for my two-mag engine.
4) Check that the fuel drain tubes are not blocked.
5) Maybe install a SlickStart

Thanks to everyone for the suggestions and help!

[Guest]

3 hours ago, DaV8or said:

Why does everyone in this thread seem to assume the OP has Slick mags?? I couldn't find anywhere he says that. He may have Bendix mags for all we know. He does mention the Slick Start system, but that is not a mag and he doesn't currently have it. Slick Start works with Bendix as well, you don't need to have Slick mags.

You're right it is an assumption but is based on what the Lycoming factory generally supplies with their engines.

Way back in history before TMC acquired Bendix magneto, Lycoming used a lot of Bendix mags.  Lycoming reduced their dependency on their competitor by switching many engines to Slick magnetos, which Champion has since turned into junk.

Clarence

[jetdriven]

Before I spent 1000$-1500$  on two mag inspections (which often turns into new mags), slick start, and another 500$ in labor, I'd dump the slicks and put on Bendix 1200s. While you're at it, undo The SI 1625 and get your 25 degrees timing back. There's 3 knots back that the engine and airplane were designed for. 

Continental takes slicks for cores, the only extra you are out is the cost of the harness. But the slick harness can be sold to an RV guy.   In fact i did do all this to an 88 hour factory engine. 

Edited September 5, 2016 by jetdriven

[pfactor]

1 hour ago, jetdriven said:

While you're at it, undo The SI 1625 and get your 25 degrees timing back.

What's this? I tried searching for it and couldn't find SI 1625. Do you have a link? I'd like to get 3 knots back.

The shop that overhauled the magnetos last time said they would inspect and repair for free (since it's been less than a year since mag overhaul). But I take your point -- it may not even be worth doing that, and just pre-emptively switch over to Bendix mags if Slicks can have the terrible failure modes you described.

[Jeev]

On September 4, 2016 at 2:48 PM, Mooneymite said:

It does sound like a lack of ignition.  Since you have an impulse mag instead of shower of sparks, I suspect the impulse mag.  If you plug(s) were bad, it would run badly.  Since it seems to be a starting issue, and the impulse mag only affects starting, it seems there might be a connection.

Just a guess.

I had a very similar problem.  Was hard to start hot or cold then randomly fired right up.  It was the impulse coupling on the left mag, it was "catching" sometimes and then her times it would not.  I have the A3B6 too with only 350hrs and 3 years on the new motor & Mags.   We put on an new impulse coupling ($400 for the part!!!) and she immediately started on two blades.

[jetdriven]

6 hours ago, Mooneymite said:

Strange.  When I ordered my factory reman LYC 180, I was given the choice of Bendix, or Slick.  I went with the Bendix.  I didn't suspect that a new engine would have had no choice!

as of at least, 2012, only Slicks are an option.

[jetdriven]

16 minutes ago, pfactor said:

What's this? I tried searching for it and couldn't find SI 1625. Do you have a link? I'd like to get 3 knots back.

The shop that overhauled the magnetos last time said they would inspect and repair for free (since it's been less than a year since mag overhaul). But I take your point -- it may not even be worth doing that, and just pre-emptively switch over to Bendix mags if Slicks can have the terrible failure modes you described.

Sorry its SI1325C.  MORE HERE. 

 

[N601RX]

Slick has had a problem with their cam and points not initially wearing correctly for a few years now. When they don't each wear at the same rate it causes the E-Gap to shift and results in a weak spark and hard starting. This usually shows up in the 1st 75 hrs or less after replacement or overhaul. If the e-gap is reset after the initial wear, it is usually good until the next inspection.  

[buddy]

This sounds like an impulse coupling problem. I had the same problem for months only mine had the problem with a hot start in the beginning and later with a cold start. My mechanic sent the mags out to get cheched and the shop said they were fine. After several more months with this problem it became apparent that the only way the engine would start was when the battery was just about dead and was cracking very slowly. The problem was that the impulse coupling was hanging up when the engine was cranking over fast. A new impulse coupling solved the problem. Believe it or not this also happened with my friends 201 also and he had a new impulse coupling installed and it solved his problem.

[bradp]

Fast lightweight starters don't help impulse couplings.  At some point you will gain enough RPM to retract the pawls and you will be back to advance timing.  One symptom of the impulse coupling pawls retracting is that there will be no indication of catching until you release the start on the ignition switch.  As the engine slows it will catch.  

You should be able hear an audible click with each turn of the blade.  

Call lycoming technical support with your A&P- they will give you the proper "air gap" that the spark must jump to be able to fire the AF mixture.  3/8" rings a bell.   To test disconnect your top spark plug leads.  Mixture to idle cutoff / fuel selector off.  Stay away from prop arc as per usual precaution.   Set ignition to either left or both.  Take spark plug lead spring and measure off different lengths to a good ground (alligator clip to engine works well) while passing the prop blade by hand.  

This will indicate strength of spark to the plug and verify that the impulse coupling is working at low RPM.  I.e. it will tell you whether you might have a $hitty $lick mag  or not.  

If its hot starts only that are problematic this is where fine breaks in the secondary coil of the L mag can be an issue.  To test you should have the mag in question baked in an oven - increasing resistance and expanding the material in the coil- and then bench tested for voltage drop.  

 

[pfactor]

Success!

It was pretty much what bradp said above. The magneto overhaul shop found and fixed a break in the secondary coil (they did this for free, since they had just recently done the overhaul). They said that would cause poor spark at low RPMs for start, but would be ok at higher RPMs after starting. Now that's fixed and I also installed Tempest fine wire spark plugs. The plane started right up for my mechanic today. Oh, and we decided not to install the Slick Start.

I'm looking forward to flying tomorrow!

[carusoam]

The power of MS!

Nice follow-up PFactor.

[StevenL757]

On 9/3/2016 at 11:55 PM, Bob_Belville said:

The REM38E is a Champion "massive". If they have really do have 600 hours on them that's a lot. Changing to Tempest fine wires will cost you $650+ but would be recommended by many here including me. It does not seem that that should be the problem but is could be contributing and you probably are near or past the useful life of what's in the engine now.

Seconded.  I'm on my third set of iridium fine wires across 2 engines, and will probably never use massives.  Your mileage may vary, but for me with ~1600 hours on 2 different engines so far, glad you (and PFACTOR) spent the money on the iridium fine wires.

[bradp]

I've been struggling with hot starts ever since I had my mags overhauled.  I had them re-IRANed and still have not had a great experience.  I just installed 4 additional fine wires and I'm getting acceptable hot starts.  YMMV but these things will likely pay for themselves by emptying the "piggy bank of frustration" 

[Dood]

Hie,

 

I experienced the same problem on a M20J @2100 hours, OH@1850. 

After a Mag (bendix) OH, a new starter, an injection OH, it was the same thing...

when the engine was started, there was no problem, but the start was random or impossible; first hot and then cold with time.

I started to suspect the mechanism that delays the ignition timing at the start; and I was right : the spring were at fault, despite the mag overhaul...

Now, cold and hot start are very very easy

 

[Skybrd]

On 9/9/2016 at 6:14 PM, pfactor said:

Success!

It was pretty much what bradp said above. The magneto overhaul shop found and fixed a break in the secondary coil (they did this for free, since they had just recently done the overhaul). They said that would cause poor spark at low RPMs for start, but would be ok at higher RPMs after starting. Now that's fixed and I also installed Tempest fine wire spark plugs. The plane started right up for my mechanic today. Oh, and we decided not to install the Slick Start.

I'm looking forward to flying tomorrow!

I have had the same starting problems and it turned out to be the same as yours, bad coil in the slick mag. When the mag shop checked it the left impulse mag wouldnt spark until about 2000 rpms. Mine has the same engine a3b6 with slick mags. It seemed to run ok but the starts gave me problems especially hot starts. I had about 480 hours on the factory rebuilt engine and mags. Too bad Lycoming went ro Slick mags instead of Bendix. Recently, I had to get my airplane towed back to the hanger from the gas pumps since it wouldn’t start what a humbling experience being towed with a truck and a rope. Btw, I have fine wire tempest plugs in the lower cylinders and tempest massive on the tops. 

[pfactor]

Here's an update from a couple of years after fixing the broken wire in the magneto secondary coil and switching to Tempest fine wire spark plugs. I have had zero starting problems since doing those things. Hot starts, cold starts, warm starts. It's all great now.

[DonMuncy]

Very good news. I wish everyone's problem ended up as well.

[MisfitSELF]

On 9/5/2016 at 4:27 AM, M20Doc said:

You are understanding it correctly. It can be tested easily by disconnecting the P leads from the mags and connecting an Easter mag synchronizer the the P leads.  Turn on the synchrizer and then cycle the mag switch the lights on the synchrizer should follow switch position.  In the start position the right light will tell the configuration of the switch and ground strap.

Clarence

I happen to have a A3B6 like the OP and it would appear my ignition switch is modified per M20-59A.  What you are saying makes sense but can you tell me where it is "officially" documented that M20-59A needs to be reversed if you have the dual mag? 

Unfortunately all the service instruction says it's "to improve starting characteristics" but it doesn't say why so I can't say for sure that if you have one mag configuration you should have apply M20-59A and if you have another you shouldn't.  Please don't get me wrong, I'm not questioning your knowledge.  I just want the bulletin or instruction I can show my A&P as to why the reversal needs to be done.

[Guest]

5 hours ago, MisfitSELF said:

I happen to have a A3B6 like the OP and it would appear my ignition switch is modified per M20-59A.  What you are saying makes sense but can you tell me where it is "officially" documented that M20-59A needs to be reversed if you have the dual mag? 

Unfortunately all the service instruction says it's "to improve starting characteristics" but it doesn't say why so I can't say for sure that if you have one mag configuration you should have apply M20-59A and if you have another you shouldn't.  Please don't get me wrong, I'm not questioning your knowledge.  I just want the bulletin or instruction I can show my A&P as to why the reversal needs to be done.

If your engine is equipped with 2 impulse couplings, then removal of the grounding link at the switch is correct.  However if you have only 1 impulse coupling on the left magneto the grounding link is required to ground the right magneto while the ignition switch is in the start position.  Without the ground link the right magneto will be live and firing in the full dvanced position, while the left magneto will be delayed by the impulse coupling.  Firing the right magneto in the advanced position can damage the starter by kick back.

Clarence

[MisfitSELF]

Clarence,

Again, that makes sense but where is this documented?  The service instruction says to remove the grounding link, but doesn't say if and when you should leave it or reinstall it.  I'm looking for an official service bulletin or instruction.

Bruce

[PT20J]

On 6/11/2019 at 6:06 AM, MisfitSELF said:

Clarence,

Again, that makes sense but where is this documented?  The service instruction says to remove the grounding link, but doesn't say if and when you should leave it or reinstall it.  I'm looking for an official service bulletin or instruction.

Bruce

This is just one of those cases where it helps to understand how the systems work and how Service Instructions are created. Clarence's description of the system is correct. Knowing whether to remove or install the strap comes from understanding the ignition switch or reading the Bendix manual for the switch. The ignition switches come with the strap installed as the most common configuration is a single impulse coupling-equipped magneto. Way back in 1982 when SI M20-59A was written, Mooney realized that for the serial number ranges listed the link was installed and could be removed. That's all the SI covers. Later models (my 1994 M20J, for instance) were built with the strap removed. It was up to me and my A&P to figure out that we needed to install the strap when changing the engine from an IO-360-A3B6D to an IO-360-A3B6. Although Mooney shipped M20Js with both engines, it never produced a document detailing a procedure to change from one engine model to the other. The IPC does correctly lists the parts for both engines, but there are no drawings or instructions.

Skip

Edited June 13, 2019 by PT20J

[Guest]

On 6/11/2019 at 9:06 AM, MisfitSELF said:

Clarence,

Again, that makes sense but where is this documented?  The service instruction says to remove the grounding link, but doesn't say if and when you should leave it or reinstall it.  I'm looking for an official service bulletin or instruction.

Bruce

I don’t know of anything official other than my understanding of how the switch works.  If you need clarification you could contact Mooney for guidance.

Clarence

[Guest]

On 6/11/2019 at 9:06 AM, MisfitSELF said:

Clarence,

Again, that makes sense but where is this documented?  The service instruction says to remove the grounding link, but doesn't say if and when you should leave it or reinstall it.  I'm looking for an official service bulletin or instruction.

Bruce

I don’t know of anything official other than my understanding of how the switch works.  If you need clarification you could contact Mooney for guidance.

Clarence

[MisfitSELF]

I’ve kept on digging and what I’ve managed to find is that my A3B6 may be properly configured with the jumper removed.  The Champion/Slick site isn’t really clear but my right Mag (different model number than my left mag) may not have the impulse coupler.