M20J won't start and my mechanic is stumped

[pfactor]

I've got a 1977 J model with a Lycoming IO-360-A3B6. The other day I couldn't get it to cold start. Those have never been a problem for me. The prop turned, but there was no sputter or any a hint of combustion. I deliberately flooded the engine and tried a flood start, same deal -- no sputter.

My local mechanic took a look, and couldn't figure out what was wrong. The spark plugs are firing, the P-lead is good, he checked the ignition switch and even tried bypassing the switch to see if that would help. Finally he put everything back together and gave it one last try and managed to get it started. He said the engine ran poorly after that start, but it may have had too much fuel after all the previous attempts. But he did get it started, and he told me to try it and see it would start for me.

Last Saturday, it started immediately on my first cold start attempt. The runup was perfect, and engine operation was smooth for the 1.5 hour flight, with a good in-flight mag check. Went back to fly last Sunday and I was back to the original no start problem. No sputters, nothing. Flooded start didn't work either. Grrrrrr!

So it's back in the shop and my mechanic is stumped. He says he's checked everything he can think of. The spark plugs are firing, the timing is within 2 degrees (he's going to adjust that). The ignition switch seems to work correctly, and bypassing it doesn't help.

He mentioned that he's a big fan of SlickStart and has one in his airplane. He's not positive it will fix my problem, but it could help. I've seen mixed reviews in searching.

I've been reading some threads that mention switching to Tempest fine wire plugs has helped some people with starting issues. I'm wondering if I should try those over the SlickStart.

Other items of note:

• The magnetos were overhauled last November at annual. I've flown about 60 hours since then.
• The engine is a factory reman with about 1000 hours on it
• The spark plugs are REM38E (looking at my logbook -- it doesn't say the brand, but I think they are Champion). They have about 600 hours on them. My mechanic says they tested good. I don't know if he's tested the resistance (I just read up on that this weekend).
• The plane has an impulse coupling, not a shower of sparks.
• At my request, my local mechanic has talked with Mark Rouch at Top Gun Aviation. Mark is equally stumped about what's going on.

Any ideas or suggestions would be appreciated.

Edited September 4, 2016 by pfactor
Added note about impulse coupling

[takair]

Do you have shower of sparks?  If so, contacts may need resurface or replacement or it's simply not coming on line.  Let us know if it's this or impulse coupling.

[pfactor]

I have an impulse coupling. I updated the original post with that now.

[jetdriven]

We've had many airplanes that may show a spark, will not start because the Slick mag degrades to the point it won't light of the fuel.  We changed about 12 in one year because of this, one airplane had both fail within about 10 hours of each other, and the mags had about 250 hours.   

Find a known good mag and try it. One board member here had a new Slick put on and the #4 CHt was very hot. After several grand in diagnosis and replacing parts, he even overhauled he engine.  The hot #4 persisted.  It was the new slick mag he had just installed. 

Edited September 4, 2016 by jetdriven

[Rustler]

Long shot but one that worked for me on my '78J: check the ignition switch. I changed mine when I began to get very sporadic starting, and it solved the problem.

[Bob_Belville]

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.

[Guest]

I agree with Byron, it's most likely the magnetos. The engine needs fuel, air and sparks to run.  Champion/ Slick mags are famous for crappy parts.

Not sure if you have dual impulse mags? But early J models had a wiring error on the ignition switch when using D3000 mags look into SI M20-59.

Clarence

[ArtVandelay]

Make sure your drain tubes aren't blocked, one allows fuel to drain out and if block will cause your problem, ask me how I know. Mine are underneath left cowling flap, 3 cable tied together.

[pfactor]

13 hours ago, M20Doc said:

Not sure if you have dual impulse mags? But early J models had a wiring error on the ignition switch when using D3000 mags look into SI M20-59.

I think I've only got the impulse coupling on the left mag. I found this SI M20-59, but that's about the landing gear. Did you mean a different one?

[pfactor]

8 hours ago, teejayevans said:

Make sure your drain tubes aren't blocked, one allows fuel to drain out and if block will cause your problem, ask me how I know. Mine are underneath left cowling flap, 3 cable tied together.

Good idea. This isn't a conclusive indication, but when I deliberately flooded the engine to try to start, I had fuel coming out the drain tubes (as I was pushing the plane back in after giving up).

I was wondering if there could be a problem like too much fuel at start time causing the behavior we're seeing. I'll ask the mechanic to check out the drain tubes.

[pfactor]

14 hours ago, 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.

I think I'm going to have to decide between spending around the same amount of money for either a SlickStart or new Tempest fine wires. I'm leaning towards the new spark plugs since I haven't seen any support for the SlickStart idea.

Oh, and the shop that overhauled the magnetos last year says they'll re-inspect and fix them for free. So we're going to do that as well.

[kevinw]

+1 to Bobs post. I just installed tempest fine wire plugs and my engine has never started better. Plenty of other benefits but suffice it say the new plugs are one of the best upgrades I did. On a side note, I have the electroair ignition system and they recently began offering fine wire plugs. I did all 8 with two different type of plugs.

Sent from my iPhone using Tapatalk

[Oldguy]

I switched over to Tempest massives two annuals ago and have had no problems with hot or cold starts. As Bob said earlier, 600 hours on the Champions are a lot. Massive or fine wire - the Tempest plugs appear to have a better reputation than the Champion ones.

[DaV8or]

Change the plugs. Get the Tempest ones either massive, or fine wire. I have the Slick Start and it might help you, but start with the plugs. Plugs are relatively cheap and easy and very well might solve your problem.

The Slick Start is basically a solid state version of the shower of sparks system. I have read that most believe the SOS to be superior to impulse coupling. The Slick Start will provide the hottest spark of all, but unfortunately it's power is lost on the narrow gap our plugs have to run properly on the magnetos. I have often thought that what our engines need is a special "starter plug" that works in conjunction with the Slick Start and has a nice big gap to really get a massive spark. Once the engine starts and you release the ignition key, the starter plug would go off along with the Slick Start.

[Mooneymite]

18 hours ago, pfactor said:

I have an impulse coupling. I updated the original post with that now.

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.

[Piloto]

I had a similar problem in cold weather. It turn out that the electric fuel pump need to deliver at least 20 psi for a successful painless start. I replaced the pump and problem solved. The old and new pump sounded exactly the same but pressure was substantially lower on the old pump.

José 

[Guest]

7 hours ago, pfactor said:

I think I've only got the impulse coupling on the left mag. I found this SI M20-59, but that's about the landing gear. Did you mean a different one?

Here is the SI I'm referring to.

http://www.mooney.com/en/si/M20-59A.pdf

Early J models with the D 3000 magnetos used a single impulse coupling.  The magneto switch for these was spec'd out like the E and F models before, meaning there was a grounding jumper to ground the right magneto during start.  If your switch was modified per the SI, it should be returned to original with a single impulse on the left mag in your new engine.  Failure to install the ground strap will allow your right magneto to fire in the full advanced position while starting.

It is not the cause of your current difficulties, but should be checked.

Clarence

[bradp]

So Clarence if i understand correctly :

-E/F models were configured with impulse and right mag (non-impulse) was grounded out 

-A3B6D with the D3000 mag had both mags using a single impulse so both could be used for starting.   But the switch was still configured to ground out the right Mag during starts.

- the SB removes the ground jumper

- if the engine is converted back to 2x mags (A3B6), like the OP, then the switch should be examined to make sure that the SB has been undone as to avoid backfires with advance timing of the right Mag during starting   

 

Back to OP:

- it's most likely an ignition problem.

- rule out plugs 

- less likely but rule out leads

- slicks have problems with wire breaks in the secondary coil.  That will produce ineffective voltage drop.  The fact the the mags were recently overhauled points to your most likely culprit.   Try a known decent mag on and then.m see if symptoms persist.  

[Guest]

9 hours ago, bradp said:

So Clarence if i understand correctly :

-E/F models were configured with impulse and right mag (non-impulse) was grounded out 

-A3B6D with the D3000 mag had both mags using a single impulse so both could be used for starting.   But the switch was still configured to ground out the right Mag during starts.

- the SB removes the ground jumper

- if the engine is converted back to 2x mags (A3B6), like the OP, then the switch should be examined to make sure that the SB has been undone as to avoid backfires with advance timing of the right Mag during starting   

 

Back to OP:

- it's most likely an ignition problem.

- rule out plugs 

- less likely but rule out leads

- slicks have problems with wire breaks in the secondary coil.  That will produce ineffective voltage drop.  The fact the the mags were recently overhauled points to your most likely culprit.   Try a known decent mag on and then.m see if symptoms persist.  

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

[carusoam]

Clarence, this thing?

http://www.aircraftspruce.com/catalog/topages/magneto_timlt.php

Best regards,

-a-

[bradp]

Also if you end up having the mags be the issue, consider what Byron did and convert to Bendix mags.  I wish I had before I was three mags in and hard starting / no starting for Way too many months while troubleshooting. 

[DaV8or]

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.

[Mooneymite]

Just now, DaV8or said:

Why does everyone in this thread seem to assume the OP has Slick mags??

Not everyone did make that assumption!  

However.....the reason should be obvious.  

[jetdriven]

26 minutes 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.

Because the only way to get Bendix mags was convert to them, Lycoming refuses to ship new engines with anything but slicks, and then warranty on those is one year. 

[Mooneymite]

35 minutes ago, jetdriven said:

Because the only way to get Bendix mags was convert to them, Lycoming refuses to ship new engines with anything but slicks, and then warranty on those is one year. 

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!