Antique Engines and Old Iron
[Home] - [HELP] - [Forums] - [Library] - [Photo Gallery] - [Groups] - [Classified Ads] - [Subscribe] - [Links] - [Books] - [Sponsors] -

Go Back   SmokStak > SmokStak® Antique Engine Community > Magnetos, Ignition Coils and Spark Plugs
Forgot Password? Join Us!

Notices

Magnetos, Ignition Coils and Spark Plugs Discussion about magnetos, buzz coils, spark plugs, ignitors and low tension coils.

Magnetos, Ignition Coils and Spark Plugs

Help with Magneto Diagnosis - John Deere Type E, 3hp


this thread has 18 replies and has been viewed 11624 times

Reply
 
Thread Tools Display Modes
  #1  
Old 07-22-2011, 08:06:41 AM
nforrester nforrester is offline
Registered
 
Join Date: Jul 2011
Location: Woods Hole, Massachusetts
Posts: 4
Thanks: 0
Thanked 0 Times in 0 Posts
Default Help with Magneto Diagnosis - John Deere Type E, 3hp

I'm trying to help some folks with a new magneto on their John Deere Type E, 3hp stationary engine. History:

The engine was restored to operating condition 20 years ago. Since then it has operated weekly during the summer using a battery and coil for ignition. They recently purchased a magneto from Hit & Miss Ent., to simplify the operation (eliminate the battery and coil). The engine starts and runs without problem using the battery and coil. The ignitor was recently overhauled when the head gasket was replaced.

Here's what we've done so far:

1. Timing appears to be set correctly. The "L" button on the magneto drops into the detent when the ignitor trips, and this corresponds to the alignment of the "spark" mark on the flywheel with the exhaust push rod.

2. With the engine is running on battery and coil, probably at 550RPM but I didn't have a way to measure that, there is only a very faint yellow spark if the magneto wire is scraped across the ignitor spring or bare metal on the engine.

3. With the engine running, my DVM reads about 14-15V RMS/AC. I wish I had brought a Simpson meter, as the DVM is only specified down to 20Hz, and the mag output is less than 10Hz at 550RPM. HIt & Miss says that this is a good voltage.

4. With the engine running, the same DVM shows 0.3A RMS AC current when the meter is used to short the mag output to the engine frame.

5. I am aware of two other tests that I can perform: (a) attach and light a 12V automotive bulb (I assume that I should use a tail light, not a head light), and (b) with the mag removed from the engine, short the output to frame and feel for strong resistance during rotation of the shaft. I have NOT performed either of these tests, yet.

6. The DC resistance to ground from the output terminal measures about 17 ohms.

This is my first experience with a low-tension magneto, though I am very familiar with motors, magnetics and electrical systems. It seems to me that while the open-circuit output voltage (14V) is in the right range, that the magneto should be generating much higher current, probably amps, not tenths of amps.

Can anyone offer advice? Hit & Miss thinks the problem is with the ignitor, not the mag, but I am doubtful because the engine operates fine with battery and coil.

Thanks.
Reply With Quote
Sponsored Links
  #2  
Old 07-22-2011, 08:49:59 AM
Elden DuRand's Avatar
Elden DuRand Elden DuRand is offline
In Memory Of
 
Join Date: Nov 2004
Location: Port St. Joe, Florida, USA
Posts: 7,833
Thanks: 13,116
Thanked 7,895 Times in 2,966 Posts
Images: 11
Default Re: Help with magneto diagnosis - John Deere Type E, 3hp

Hit & Miss is pretty good with diagnoses so I'd suspect the ignitor. With battery and coil, you get a hotter spark and, if there's some electrical leakage in the micas, it could overcome the weaker output from the mag.

Things to do to isolate the problem. Get the engine running and, by quickly disconnecting the coil from the ignitor, and connecting the magneto (do NOT parallel them!), see if the engine will run on the mag when it's up to speed. If it runs, I'd suspect any of the following:

- Make sure the magneto frame is solidly grounded to the engine frame.

- Make sure the mag is actually timed correctly to the engine.

- If the magneto was accidentally connected to the battery, that could have partially discharged the magnet. In that case, recharging the magnet would probably fix the problem.

- If, during shipment, the magneto was exposed to a strong magnetic field, the magnet could have been partially discharged. Recharge the magnet.

Good luck and let us know what the problem was.

Take care - Elden
http://www.oldengine.org/members/durand
__________________
[SIGPIC][/SIGPIC]
Take care - Elden
http://www.eldensengines.com
Reply With Quote
  #3  
Old 07-22-2011, 09:18:41 AM
nforrester nforrester is offline
Registered
 
Join Date: Jul 2011
Location: Woods Hole, Massachusetts
Posts: 4
Thanks: 0
Thanked 0 Times in 0 Posts
Default Re: Help with magneto diagnosis - John Deere Type E, 3hp

Update:

We found a marker light for a trailer. The bulb draws 0.3A from a 12V battery, and lights brightly. On the magneto, with the engine running at speed, it lights only dimly.

---------- Post added at 09:13 AM ---------- Previous post was at 08:57 AM ----------

Quote:
Originally Posted by Elden DuRand View Post
Hit & Miss is pretty good with diagnoses so I'd suspect the ignitor. With battery and coil, you get a hotter spark and, if there's some electrical leakage in the micas, it could overcome the weaker output from the mag.
OK, on the mag being weaker. I wasn't sure what to expect.

Quote:
Things to do to isolate the problem. Get the engine running and, by quickly disconnecting the coil from the ignitor, and connecting the magneto (do NOT parallel them!), see if the engine will run on the mag when it's up to speed.
I forgot to mention that we tried that test yesterday. On the mag, the engine had no ignition, but resumed operation, from coasting, when the battery/coil was reattached. We were careful not to connect both at once.

Quote:
If it runs, I'd suspect any of the following:

- Make sure the magneto frame is solidly grounded to the engine frame.
I verified all the grounds with an ohmmeter. Fixed one bad one related to the battery setup, but that would not have affected the mag connection.

Quote:
- Make sure the mag is actually timed correctly to the engine.
Yes, we checked that by the rivet/detent on the mag.

Quote:
- If the magneto was accidentally connected to the battery, that could have partially discharged the magnet. In that case, recharging the magnet would probably fix the problem.

- If, during shipment, the magneto was exposed to a strong magnetic field, the magnet could have been partially discharged. Recharge the magnet.
I'll look into that and see if we have the means to do that. I think I saw instructions on this site. I'll look, or a link might be helpful.

Quote:
Good luck and let us know what the problem was.
Will do, if we ever get it working. Thanks for the quick reply.

Quote:
Take care - Elden
http://www.oldengine.org/members/durand


---------- Post added at 09:18 AM ---------- Previous post was at 09:13 AM ----------

Update:

We found a marker light for a trailer. It draws 0.3A from a 12V battery and lights brigtly. Connected to the mag, with the engine running at speed, it lights only dimly.
Reply With Quote
  #4  
Old 07-22-2011, 01:32:37 PM
Andrew Mackey Andrew Mackey is offline
Sponsor
 
Join Date: Nov 2004
Location: Rockaway, New Jersey USA
Posts: 14,023
Thanks: 1,983
Thanked 6,591 Times in 4,245 Posts
Exclamation Re: Help with magneto diagnosis - John Deere Type E, 3hp

A yellowish spark indicates either a bad coil or poor ground. The coil must be grounded at one end to the case of the mag. the other end must go to the output post. Check the output post for degradation of the isolation material, and that the grounding point for the coil is clean and shiny. Corrosion between the copper coil wire and the zinc case is possible. What is your mag power lead made of? It should be 10 or 12 guage single strand wire, not multistrand. Try dragging the output wire across the mag case, on a clean bright metal spot, and see if spark quality improves. Where the mag mounts to the engine, it should be shiny metal clean, free of corrosion and debris. Even on the underside, where the bolt heads contact. Look carefully at the mag base, as the surface is often corroded and pitted. If still no spark, check the following:

Carefully note whe location of the mag and engine shafts, and remove the mag. Spin the mag over, and note the resistance to turning. You should feel resistance as the armature cuts the magnetic lines of force. NOW - ground the lead out wire to the mag case. You chould feel a marked difference in rotation, rhe mag may even stop turning momentarily. If it does not, then recharge of the magnets is warrented. If I remember right, this mag has brushes. While you have the mag off, you might pull the brush mountcovers off, and see if there is oil on the brushes. Oil contamination will definately affect spark. The oil would come from over oiling or if the mag was tipped during transport (common occurance). Again, while the mag is off, make sure that the armature is not touching the poles within the core, as contact will temporarily magnetize the armature, rendering it inneffective. If you attempt to dis-assemble the mag, you must remove the brushes, or the armature may be damaged.

As for the ignitor - check the fixed post for carbon deposits, and clean off the Mica isolation. A battery and coil puts out a lot of current, and at low speed, a mag does not. The mag may fire while under battery and coil, but will short out enough to not fire on the mag. Also, make sure that the movable point shaft is free of paint and combustion residue. Over ioling the shaft may cause resistive gunk to build up under the tapered gas seal on the shaft. All metal surfaces on the ignitor springs and shaft should be clean and shiny bright
Andrew
Reply With Quote
  #5  
Old 07-22-2011, 03:06:14 PM
nforrester nforrester is offline
Registered
 
Join Date: Jul 2011
Location: Woods Hole, Massachusetts
Posts: 4
Thanks: 0
Thanked 0 Times in 0 Posts
Default Re: Help with magneto diagnosis - John Deere Type E, 3hp

Quote:
Originally Posted by Andrew Mackey View Post
A yellowish spark indicates either a bad coil or poor ground. The coil must be grounded at one end to the case of the mag.
I presume the grounded end of the coil must be attached to the shaft. None of the drawings or parts lists I have seen indicate a second brush for the grounded end. I assume the ground connection is made through the bearings and gears.

Quote:
the other end must go to the output post. Check the output post for degradation of the isolation material, and that the grounding point for the coil is clean and shiny. Corrosion between the copper coil wire and the zinc case is possible.
This is a new, or newly overhauled, mag. The output post looks new. I have removed it and cleaned the slip ring per the John Deere manual (cloth held against the ring with a pencil while slowly rotating the engine).

Quote:
What is your mag power lead made of? It should be 10 or 12 guage single strand wire, not multistrand.
The wire appears to be AWG 12 of the sort that can be extracted from ROMEX.

Quote:
Try dragging the output wire across the mag case, on a clean bright metal spot, and see if spark quality improves.
I will try that. It's a bit tricky because the mag is behind the flywheel and I wish to keep all my fingers.

Quote:
Where the mag mounts to the engine, it should be shiny metal clean, free of corrosion and debris. Even on the underside, where the bolt heads contact. Look carefully at the mag base, as the surface is often corroded and pitted.
I was not present when the mag was installed, so we'll have to disassemble to verify. An ohmmeter confirms a connection of less than 0.5ohms, but I realize that that may not be good enough.

Quote:
If still no spark, check the following:

Carefully note the location of the mag and engine shafts, and remove the mag. Spin the mag over, and note the resistance to turning. You should feel resistance as the armature cuts the magnetic lines of force. NOW - ground the lead out wire to the mag case. You should feel a marked difference in rotation, the mag may even stop turning momentarily. If it does not, then recharge of the magnets is warranted.
I want to do this test, which also calls for disassembly of the mag from the engine. Standby.

Quote:
If I remember right, this mag has brushes. While you have the mag off, you might pull the brush mountcovers off, and see if there is oil on the brushes. Oil contamination will definately affect spark. The oil would come from over oiling or if the mag was tipped during transport (common occurance).
I think there is only one brush for the output lead. If I disassemble the mag, I will check it all carefully.

Quote:
Again, while the mag is off, make sure that the armature is not touching the poles within the core, as contact will temporarily magnetize the armature, rendering it ineffective. If you attempt to dis-assemble the mag, you must remove the brushes, or the armature may be damaged.
This is a new mag, not owned by me. I am thus hesitant to disassemble it, but I would really like to, so that I can verify that it is assembled correctly. Standby on that, too.

Quote:
As for the ignitor - check the fixed post for carbon deposits, and clean off the Mica isolation. A battery and coil puts out a lot of current, and at low speed, a mag does not. The mag may fire while under battery and coil, but will short out enough to not fire on the mag. Also, make sure that the movable point shaft is free of paint and combustion residue. Over oiling the shaft may cause resistive gunk to build up under the tapered gas seal on the shaft. All metal surfaces on the ignitor springs and shaft should be clean and shiny bright
Andrew
OK. I haven't seen the inside of the ignitor, yet. I am told that the mica was all replaced this winter. The outside parts are definitely NOT shiny. Things are starting to point in the direction of the ignitor.

Thanks.
Reply With Quote
  #6  
Old 07-22-2011, 04:43:36 PM
BobRR BobRR is offline
Registered-III
 
Join Date: Oct 2004
Location: Ypsilanti, Michigan, USA
Posts: 3,309
Thanks: 8,444
Thanked 1,391 Times in 944 Posts
Default Re: Help with magneto diagnosis - John Deere Type E, 3hp

I wonder if they moved the ignitor spring so that it holds the points open (to save the battery) instead of closed? Bob
Reply With Quote
  #7  
Old 07-22-2011, 09:18:21 PM
nforrester nforrester is offline
Registered
 
Join Date: Jul 2011
Location: Woods Hole, Massachusetts
Posts: 4
Thanks: 0
Thanked 0 Times in 0 Posts
Default Re: Help with magneto diagnosis - John Deere Type E, 3hp

No, the points stay closed except when tripped. Eats the battery, which is why they want to go to a mag. The battery normally runs with a 0.9ohm coil and a 6.5ohm ballast resistor on a 12V battery. I know they would be better off with 6 or 2V battery, or at least a larger (10-15 ohm) ballast resistor, but that's a different project. I'll suggest that next year if the mag still does not work.

---------- Post added at 09:18 PM ---------- Previous post was at 09:00 PM ----------

A "final" summary, as I will be leaving my hosts in the morning:

We elected not to remove the mag, and thus could not disassemble it or do further tests. The guy who installed the mag assures me that he scraped the mounting surface clean before bolting on the mag.

Dragging the mag wire directly on the mag case, with the engine running as speed, produced the same weak spark (yellow and some blue but small).

I did remove the ignitor. While the micas were all changed recently, and in good shape, the the rest of the ignitor appears not to have had much attention. The ignitor was sooted up, and the points were rough with pits. I cleaned it up a bit, and dressed the points with sand paper, but still no joy.

After they are done making ice cream for the season (Sept.), the plan is to send the ignitor out for service to one of the shops that knows more about this.

What I fail to understand is: if the mag/ignitor combination is so finicky, how did folks keep these things running reliably in the field when they were in regular use?

Thanks to all for the advice and suggestions.
Reply With Quote
  #8  
Old 10-03-2014, 10:02:51 AM
dick vye dick vye is offline
Registered
 
Join Date: Mar 2008
Location: auburn me. usa
Posts: 6
Thanks: 2
Thanked 2 Times in 2 Posts
Default Re: Help with magneto diagnosis - John Deere Type E, 3hp

Should there be continuity between the two slip rings when you have the armiture in hand? Thank you very much. Dick Vye Maine Antique Power Association rvye@roadrunner.com
Reply With Quote
  #9  
Old 10-03-2014, 10:19:18 AM
DieselAddicted DieselAddicted is offline
Subscriber
 
Join Date: Sep 2010
Location: Mount Vernon, Ohio
Posts: 728
Thanks: 113
Thanked 788 Times in 337 Posts
Default Re: Help with magneto diagnosis - John Deere Type E, 3hp

Quote:
Originally Posted by nforrester View Post

What I fail to understand is: if the mag/ignitor combination is so finicky, how did folks keep these things running reliably in the field when they were in regular use?

Thanks to all for the advice and suggestions.
Large numbers of magneto/ignitor engines have been converted to high tension ignition and spark plug and many more still have the ignitor but had battery box and coil hung on them somewhere and the mag is either gone of just there for looks. I guess that they never were the most reliable system to begin with? Even with everything original in place many guys that start on a battery and coil then run on the mag. Although i am far from an expert it would appear that the system is maintenance heavy at the very least.
Reply With Quote
  #10  
Old 10-08-2014, 02:18:56 PM
roosta roosta is offline
Registered
 
Join Date: Nov 2013
Location: Fort Worth, Texas
Posts: 17
Thanks: 0
Thanked 5 Times in 3 Posts
Default Re: Help with magneto diagnosis - John Deere Type E, 3hp

Did you guys ever figure out the issue on this debug? Just curious what the solution was.
Reply With Quote
  #11  
Old 03-29-2015, 07:34:25 PM
guzzi1 guzzi1 is offline
Registered
 
Join Date: Aug 2014
Location: Altona, Manitoba, Canada
Posts: 10
Thanks: 0
Thanked 1 Time in 1 Post
Default Re: Help with magneto diagnosis - John Deere Type E, 3hp

I noticed you said the points were closed, they should be open, closed only when tripped. You're shorting out your ignition system. You ignitor springs are not installed correctly. I have just finished rebuilding the same engine.
Reply With Quote
  #12  
Old 03-29-2015, 08:41:41 PM
FarmSC's Avatar
FarmSC FarmSC is offline
Subscriber
 
Join Date: Sep 2006
Location: Seneca, South Carolina, USA
Posts: 1,092
Thanks: 2,176
Thanked 977 Times in 343 Posts
Default Re: Help with magneto diagnosis - John Deere Type E, 3hp

According to John Deere, you are INCORRECT. JD E's with the rotary mag and ignitor are Normally closed.

See attached photos from JD Service bulletin from 1934
Attached Thumbnails
Click image for larger version

Name:	jd2.jpg
Views:	55
Size:	82.9 KB
ID:	222178   Click image for larger version

Name:	jd1.jpg
Views:	97
Size:	115.8 KB
ID:	222179  
__________________
Kevin Harbin
Seneca, SC
www.snowcreekmills.com
Reply With Quote
The Following 2 Users Say Thank You to FarmSC For This Post:
  #13  
Old 03-31-2015, 12:45:31 AM
guzzi1 guzzi1 is offline
Registered
 
Join Date: Aug 2014
Location: Altona, Manitoba, Canada
Posts: 10
Thanks: 0
Thanked 1 Time in 1 Post
Default Re: Help with magneto diagnosis - John Deere Type E, 3hp

I know what the manual says but it works best with points open, I'm running 1 engine 3hp with mag/ignitor and the other 1.5hp battery/coil with ignitor and they start and run flawless. Try it you'll love it.
Reply With Quote
  #14  
Old 03-31-2015, 02:16:07 AM
Dick Graybill's Avatar
Dick Graybill Dick Graybill is offline
Subscriber
 
Join Date: Nov 2004
Location: McAlisterville, Pennsylvania, USA
Posts: 1,734
Thanks: 1,082
Thanked 690 Times in 500 Posts
Default Re: Help with magneto diagnosis - John Deere Type E, 3hp

As farmsc said,on a J D with mag, points should be closed. When they trip open they make spark. If using a batt and coil points should be adjusted open or you will drain battery very quickly, and if it stops and you don't catch it right away you can fry your coil. Don't ask how I know.
Reply With Quote
  #15  
Old 03-31-2015, 08:27:37 PM
OTTO-Sawyer's Avatar
OTTO-Sawyer OTTO-Sawyer is offline
Subscriber
 
Join Date: Nov 2008
Location: Scioto Mills, Illinois USA
Posts: 9,025
Thanks: 20,560
Thanked 8,037 Times in 3,804 Posts
Default Re: Help with magneto diagnosis - John Deere Type E, 3hp

Right or Wrong, mine ran perfectly fine with the points open.
https://youtu.be/ZUWEXXaJQ0g
Mag only put out about 1 1/2 volts cranking and barely 5 volts when running, but even burning off all the excess oil the previous owner had put in the crankcase it started and ran great with the points set open.

I set them open when I rebuilt the ignitor because I didn't know yet it the mag was any good or not and ran it on battery & coil the first couple times while I checked things out on it.

After getting it running and checking the mag voltage I switched it over from battery to mag while running and then shut it down to see if it would start on 1 1/2 volts cranking. It did so I left the points open.

I never tried it with them closed though to see if it ran any better one way or the other so I can't confirm or deny what guzzi1 says about them working "best with points open".

All I know is mine ran great open.

__________________
I just keep coming back again and again like the Evil Twin of a Bad Penny !
http://www.youtube.com/user/oldSawyer?feature=watch
Reply With Quote
The Following User Says Thank You to OTTO-Sawyer For This Post:
  #16  
Old 04-02-2015, 01:23:53 PM
Andrew Mackey Andrew Mackey is offline
Sponsor
 
Join Date: Nov 2004
Location: Rockaway, New Jersey USA
Posts: 14,023
Thanks: 1,983
Thanked 6,591 Times in 4,245 Posts
Exclamation Re: Help with magneto diagnosis - John Deere Type E, 3hp

Timing points opening is critical on a mag fired engine. The points must open at exactly the time of maximum magnetic flux. early or late - no spark. If the mag is off 1 tooth, you may not get spark. JD had a problem with weak coils, that's why you find many E type engines with associated mags. You should get a pretty bright flash, dragging the power output across the case of the mag at speed. If you don't get a good flash, I would suspect bad coils or poor brush connections. Even though the mag has fair voltage, if the current isn't there, you won't get good flash. Only way to tell is to remove the mag from the engine and test as I posted earlier. As an experiment, you might try rotating the mag 180 degrees and re-install. Some IHC M engines I have worked on had batter spark - the timing mark on the mag was slightly off center, enough to make a difference.
Reply With Quote
  #17  
Old 04-04-2015, 02:57:09 PM
guzzi1 guzzi1 is offline
Registered
 
Join Date: Aug 2014
Location: Altona, Manitoba, Canada
Posts: 10
Thanks: 0
Thanked 1 Time in 1 Post
Default Re: Help with magneto diagnosis - John Deere Type E, 3hp

Nforrester makes a great point, time your mag with the "L" rivet. My 3 hp mag timing mark was marked 1 tooth off on the gear which is critical to get the most voltage at the right time for a good spark.
Reply With Quote
  #18  
Old 02-24-2018, 02:05:53 PM
allenrhowe allenrhowe is offline
Registered
 
Join Date: Jan 2016
Location: Waterloo, Wisconsin
Posts: 2
Thanks: 0
Thanked 0 Times in 0 Posts
Default Re: Help with magneto diagnosis - John Deere Type E, 3hp

how do you re energize the magnets on a 1 1/2 hp john deere mag
Reply With Quote
  #19  
Old 02-25-2018, 12:54:34 AM
cobbadog cobbadog is offline
Registered-III
 
Join Date: Aug 2009
Location: Coopernook. N.S.W. Australia
Posts: 1,726
Thanks: 3,138
Thanked 754 Times in 517 Posts
Default Re: Help with magneto diagnosis - John Deere Type E, 3hp

You do need a 'recharger' to re energise your magnets. If you are in a club someone there should be able to help otherwise look in the 'sponsors' page for one near you that can service your magneto.
Or you can get the plans off this site to make your own recharger.
Reply With Quote
Reply

Bookmarks


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

F o r u m Jump

Similar Threads Chosen at Random
Thread Thread Starter F o r u m Replies Last Post
john deere type e mag piciron Magnetos, Ignition Coils and Spark Plugs 1 08-04-2015 09:03:28 AM
John Deere Type E Tom TypeE Hit & Miss Gas Engine Discussion 0 07-27-2015 09:41:26 AM
John Deere Type E 1.5hp Tom TypeE Hit & Miss Gas Engine Discussion 2 04-20-2014 09:00:29 AM
John Deere Type E dhatfiel Hit & Miss Gas Engine Discussion 4 07-21-2007 11:43:35 AM
john deere type E bob adams Antique Engine Archives 1 10-21-1999 07:42:28 PM


Use "Ctrl" mouse wheel to change screen size.
All times are GMT -4. The time now is 12:24:01 PM.

Smokstak and Enginads site search!


All use is subject to our TERMS OF SERVICE
SMOKSTAK® is a Registered Trade Mark - A Community of Antique Engine Enthusiasts
Copyright © 2000 - 2019 by Harry Matthews P.O. Box 5612 - Sarasota, FL 34277