Engine starting problem

[Guest]

I don’t have the 1967 ignition schematic handy, but I’m sure they’re all the same.

 

[Shadrach]

Interesting thread. You’re not alone.

 

 

 

 

 

 

Edited March 15, 2019 by Shadrach

[Andy95W]

1 hour ago, Shadrach said:

What you describe is not stock. I have never met an SOS system that didn’t have the six position switch. I look forward to finding out which switch was actually used.

M20s before mid1963 did not have the push to start function, and they did have SoS.  They are the ones that have the extra switch to disable the starter relay.

I modified my M20C to use the ACS switch without push-to-start, fully documented on a 337, and submitted to the FAA.  My basis for approval was that the switch is PMA'ed for other aircraft and that I placed the aircraft into a configuration previously approved by the manufacturer. I added the switch to disable the starter IAW previous serial numbers.

The way I rationalized this mod could only apply to the M20C and M20D, both of which have this configuration shown in the electrical schematic in the service manual.  The M20E and up do not.

 

[Shadrach]

8 hours ago, Andy95W said:

M20s before mid1963 did not have the push to start function, and they did have SoS.  They are the ones that have the extra switch to disable the starter relay.

I modified my M20C to use the ACS switch without push-to-start, fully documented on a 337, and submitted to the FAA.  My basis for approval was that the switch is PMA'ed for other aircraft and that I placed the aircraft into a configuration previously approved by the manufacturer. I added the switch to disable the starter IAW previous serial numbers.

The way I rationalized this mod could only apply to the M20C and M20D, both of which have this configuration shown in the electrical schematic in the service manual.  The M20E and up do not.

 

That’s an excellent solution. A similar argument might be made for later models. The OPs plane is a 67F model and the push to start is the only approved switch I know of.

I’ve my doubts that the OP’s switch is an approved installation.  What’s more, is that it seems that it was installed without verifying functionality. What a pity it would be to have to pull that starter because of a needless kickback.

I think that paying $600 for an ignition switch is ridiculous but it’s the only “turn key” ()solution. 

Edited March 16, 2019 by Shadrach

[skydvrboy]

1 hour ago, Shadrach said:

I’ve my doubts that the OP’s switch is an approved installation.  What’s more, is that it seems that it was installed without verifying functionality.

I suspect you are probably right.

@Andy95W  Thanks for posting the schematic.  I have printed that out and will take it with me when I go see the mechanic tomorrow.  

[skydvrboy]

Ok got to talk with the mechanic today. They are going check it out but weren’t able to today.

The part number for the kit was A3650-2.

[SheryLoewen]

Its trying to start on the right Mag as you relax the key.  Something in the the Left mag starting points is not right. Trust me I've been there.

[skydvrboy]

Well, the mechanic had a chance to look this over.  Said the first time they tried, it started perfectly.  They checked wiring of the recently installed ignition and everything matched their schematic and the one that I proved that was posted above.  They then tried starting it again and it did just what I had described, wouldn't start until releasing the key and then fired immediately.  They tried a few more times with varying degrees of success by moving the throttle, getting it to start without releasing the key.

They now think it is fuel related since they were able to get it to start a few times without releasing the key.  I've flown it once since.  The first start happened relatively easily, right as I let go of the key.  I let it set for about an hour at my destination and then had some difficulty starting it, but it did start and NOT when I let go of the key.  I think I'm more confused than when I started!

[Guest]

How did it go from starting OK to a switch repair and now it’s the fuel system?  If they removed the wires from the back of the switch, they may have something crossed, and if they replaced the internal contacts, they may have one of the triangular contacts in the wrong hole.  I’ve seen this before.

I have the TCM ignition switch manual if you need it.

Clarence

[skydvrboy]

16 hours ago, M20Doc said:

How did it go from starting OK to a switch repair and now it’s the fuel system?

That's a great question.  It used to start perfectly when the engine turned over.  They added a new starter and it still wouldn't turn over.  That's when they found the switch contacts were arcing.  Replaced the switch and now I have a fuel problem?  It makes no sense, but I think the only way to get to the bottom of this is going to be to take it to another shop. GRRR!

[MIm20c]

The first thing I would do is disconnect the signal wire from the starter relay and make sure the sos runs every time you turn the key. From there move to the mag. Just my opinion. 

[ArtVandelay]

I’m curious, where are the starter relays located?


Tom

[Shadrach]

3 hours ago, ArtVandelay said:

I’m curious, where are the starter relays located?


Tom

For an F model of this vintage, It should be on the left side of the outside of the firewall. Very easy to access.

[skydvrboy]

16 hours ago, MIm20c said:

The first thing I would do is disconnect the signal wire from the starter relay and make sure the sos runs every time you turn the key. From there move to the mag. Just my opinion. 

According to the mechanic they did this and the SOS runs.

Per DMax publication referenced earlier in the thread I may just verify for myself by following these steps:

4. Remove the spark plug leads and top plugs of all cylinders. Remove the bottom spark plug leads.

5. Rotate the prop, by hand, until the number one cylinder is at Top Dead Center, TDC on the compression stroke.

6. Make certain that the starter has been disabled and cannot be activated by the ignition switch. Some early Mooneys (M20B and M20C) have a starter disengage switch located beside the starter vibrator switch. This switch was installed so that the starter relay could be disengaged to allow hand propping. NOTE: Whenever hand propping a Mooney or any aircraft with Shower of Sparks system, be sure and disconnect the starter relay. The SOS must be activated during the hand propping and you don’t want the starter to engage while someone is near the prop.

7. Hold the #1 spark plug lead by the insulation and place the spring at the end of the harness lead, very near the cylinder. Have another party in the plane turn and hold the key to the far right past “both”. The vibrator should be buzzing and a constant arc of electricity, “shower of sparks” should be seen between the tip of the lead spring and the engine cylinder. Sometimes it may be necessary to move the prop back and forth a few degrees to find the exact spot where the “retard points” will open.

I'm not exactly sure how to find TDC, but I think I can drop a rod down the spark plug hole and just feel for it.  If no sparks, I may be on the exhaust stroke, so rotate to the next "TDC" and try again.  If I get no sparks on two successive strokes, then I know I'm not getting my SOS at the cylinder.  Sound like a plan?

[Guest]

1 hour ago, skydvrboy said:

According to the mechanic they did this and the SOS runs.

Per DMax publication referenced earlier in the thread I may just verify for myself by following these steps:

4. Remove the spark plug leads and top plugs of all cylinders. Remove the bottom spark plug leads.

5. Rotate the prop, by hand, until the number one cylinder is at Top Dead Center, TDC on the compression stroke.

6. Make certain that the starter has been disabled and cannot be activated by the ignition switch. Some early Mooneys (M20B and M20C) have a starter disengage switch located beside the starter vibrator switch. This switch was installed so that the starter relay could be disengaged to allow hand propping. NOTE: Whenever hand propping a Mooney or any aircraft with Shower of Sparks system, be sure and disconnect the starter relay. The SOS must be activated during the hand propping and you don’t want the starter to engage while someone is near the prop.

7. Hold the #1 spark plug lead by the insulation and place the spring at the end of the harness lead, very near the cylinder. Have another party in the plane turn and hold the key to the far right past “both”. The vibrator should be buzzing and a constant arc of electricity, “shower of sparks” should be seen between the tip of the lead spring and the engine cylinder. Sometimes it may be necessary to move the prop back and forth a few degrees to find the exact spot where the “retard points” will open.

I'm not exactly sure how to find TDC, but I think I can drop a rod down the spark plug hole and just feel for it.  If no sparks, I may be on the exhaust stroke, so rotate to the next "TDC" and try again.  If I get no sparks on two successive strokes, then I know I'm not getting my SOS at the cylinder.  Sound like a plan?

Hold your thumb on the spark plug hole of cylinder 1(the front right cylinder) Turning the propeller by hand you should feel compression building in the cylinder.  Continue turning slowly, there are timing and TDC marks on the back of the flywheel whic should be at the top, and another set should be aligned with the left side of the starter nose case.

You can also use a a plastic pen to feel the piston crown through the upper plug hole.

Clarence

[skydvrboy]

Now you went and made me feel stupid for not thinking about putting my thumb over the hole to feel the pressure or vacuum.  Such a simple and elegant solution.

I was thinking of a pencil for the rod, but will use a pen per your suggestion.

[Prior owner]

I’m having serious trouble with my bendix switch as well, and found a few good resources to repair it- 

TCM sells a repair kit with new contacts and support plate, and they have a very informational Service Bulletin regarding inspecting and upgrading our switches, as well- it also includes how to conduct a proper continuity test on our “push to start switch”:

 Bendix Service Bulletin No. 583

TCM Bendix switch repair kit, as specified in the SB- $206.95:

 Bendix rebuild kit part No. 10-357515

A good article on Bendix and ACS switch cleaning/repair that recommends Luberex for Bendix switch lubrication, per ACS’s guidance on lubricating their ign switch, which is also affected by AD:

Bendix and ACS Switch cleaning and repair

Edited April 9, 2019 by PilotCoyote

[Buckeyechuck]

Check the bottom right post on the left mag to make certain one of the plug wires isn't shorting it to ground.  I had this problem after my mechanic installed new slicks on my C model. He couldn't figure it out. I did after breaking the nose off the starter and tearing up the ring gear. I have a used switch if you need one. Do not try to start if you don't have it repaired. You will  have a kick back and destroy the starter if it doesn't start. 

[skydvrboy]

I guess I should provide some closure to this thread.  As I mentioned, my mechanic said nothing was wrong with the initial install, but since he looked it over, I haven't had any real issues starting the plane at all.  Either the guy working for him fixed it and didn't own up to the mistake, or it was all in my head or some other unknown quirk.  Anyhow, I'm completely happy with the way it is starting now... and I learned a lot about the plane in the process.

[carusoam]

Closure is good... let us know if anything recurs...

Best regards,

-a-

[SheryLoewen]

It's definitely starting on he Right Mag as you release the switch, so something is amiss with the left mag or switch wiring. --seen this before--

Paul Loewen

[skydvrboy]

It is no longer starting when the switch is released like it was before.  Coincidentally, that stopped when they looked it over and found everything was wired correctly. 

[Buckeyechuck]

The problem I had with starting on the right mag was intermittent. The plug wire wasn't always shorting out the retard breaker terminal. Took a while to figure it out. After re-routing the plug wire and installing rubber boots on every electrical connection under the cowling, problem solved. 

[0TreeLemur]

Question: when starting my '67C, when I get to the checklist item "Open throttle 1/4" and I do that without having headphones on, I hear something click.   What is making that clicking sound?  It sounds like there is some kind of microswitch being actuated by the act of pushing in the throttle., or am I imagining that?   I assumed it had something to do with the starting process...

[jaylw314]

1 minute ago, Fred₂O said:

Question: when starting my '67C, when I get to the checklist item "Open throttle 1/4" and I do that without having headphones on, I hear something click.   What is making that clicking sound?

That's likely to be the throttle alarm microswitch that sets off the alarm when you pull throttle with the gear up.  It's based on throttle position, not MP