John Deere JS38 push mower

dannac

Member
Joined
Mar 18, 2023
Threads
2
Messages
36
Grab a good business card, loosen the coil and pull it back and tighten down. Rotate the flywheel until both magnets are across from the two legs of the coil. Insert business card into the gap, and loosen the coil, it should snap tight to the magnets. Tighten the coil down and rotate the flywheel to remove the business card. Test for spark.
Would the spacing condition of the coil now stop the mower from starting ?

The spark plug against engine did have spark.

Thanks for reply
 

woodstover

Active Member
Joined
Sep 30, 2022
Threads
3
Messages
75
Thanks for the reply Freddie21.

Thanks for that info tomw0 ... your explanation makes sense to me.

I took cover off and not sure if I want to try this with the cutting season starting.
May have to wait, as this would take me quite awhile not being familiar with this.

Did notice a little liquid at bottom of air filter frame, gas I think.
You can handle this, adjusting the valves is a 30 min job for beginners. I wouldn't get carried away with Grumpyunk's suggestion just yet, just set your clearances to .007". Make sure your valve cover gasket is in good condition or better yet replace it so you don't end up with oil leaks.
 

dannac

Member
Joined
Mar 18, 2023
Threads
2
Messages
36
You can handle this, adjusting the valves is a 30 min job for beginners. I wouldn't get carried away with Grumpyunk's suggestion just yet, just set your clearances to .007". Make sure your valve cover gasket is in good condition or better yet replace it so you don't end up with oil leaks.

Seems the valve cover gasket is in good shape and stayed intact.

Sure does not look like some of the YT videos I've watched on adjusting valves.
Not seeing how to make valve adjustments yet.

The cover I took off is where the spark plug was ... is this the wrong spot ?
 

Attachments

  • gasket.jpg
    gasket.jpg
    245.2 KB · Views: 8
  • v1.jpg
    v1.jpg
    180.9 KB · Views: 9
  • v2.jpg
    v2.jpg
    195.4 KB · Views: 8
Last edited:

Rivets

Lawn Royalty
Joined
Mar 11, 2012
Threads
60
Messages
15,357
Dannac, you are giving us bad info which is not helping your case. First you tell us you have an engine with a model number of 128M02-0423-F1. This number, when looked up is an L-head engine. In your last post your show us pictures of an OHV engine. Either you are trying to pull a fast one on us or someone has switched shrouds on your engine. This has caused a MAJOR problem for those who are trying to help you, as we have no idea of what you have, so some members are posting troubleshooting procedures for an L-head engine and others are post troubleshooting procedures for an OHV engine. That is the reason for all the conflicting posts. You need to clear this up, before you will get any good help. No need for anyone to post here any more until you tell us what is going on.
 

dannac

Member
Joined
Mar 18, 2023
Threads
2
Messages
36
Dannac, you are giving us bad info which is not helping your case. First you tell us you have an engine with a model number of 128M02-0423-F1. This number, when looked up is an L-head engine. In your last post your show us pictures of an OHV engine. Either you are trying to pull a fast one on us or someone has switched shrouds on your engine. This has caused a MAJOR problem for those who are trying to help you, as we have no idea of what you have, so some members are posting troubleshooting procedures for an L-head engine and others are post troubleshooting procedures for an OHV engine. That is the reason for all the conflicting posts. You need to clear this up, before you will get any good help. No need for anyone to post here any more until you tell us what is going on.
Thanks for the reply Rivets .... maybe we can get it cleared up.

I’ll be 70 yr old next month ... and beleive it or not, I got much better things to do than run around in circles on an internet lawn mower forum. Pull a fast one ... never.

I’m relaying info and answering questions best I can with something I’m not very familair with.

The only reason I posted the last picture ( from my riding mower, not the probllem push mower ) with the OHV cover, was to show what I see on youtube when looking for “how to adjust the valves” ... and to relay that ... my engine DOES NOT have that.
( I removed that image if causing confusion )

All the other images I’ve posted are directly from the problem engine. ( I’ll post the 1st 2 again )

Again, thanks for the reply.
 

Attachments

  • JD_JS38.jpg
    JD_JS38.jpg
    192.2 KB · Views: 0
  • JDengine01.jpg
    JDengine01.jpg
    271 KB · Views: 0
Last edited:

Rivets

Lawn Royalty
Joined
Mar 11, 2012
Threads
60
Messages
15,357
Well that does clear some things up, but does creat other problems. First I’m well north of 70 so age has nothing to do with it. How well you understand the operation of a small engine means everything in this case. Your first mistake was watching boobtube videos and believing that the person who posted knew what they were doing. Second, you didn’t know there was a difference between L-head and OHV engines which greatly contributed to the problem. Checking and adjusting valve clearance on an L-head engine is about 50 times harder for a DIY guy, than an OHV engine. That is why I never recommend the DIY guy’s attempt this, as you can cause expensive problems very quickly.
At this point I don’t know how to help you in this thread, because it has become so confusing with correct and misleading information. Trying to figure out which posts are good and which ones are bad is not something I want to attempt. Maybe someone else would like to try to tackle it. You’ll have to decide how you want to proceed, but as you said earlier, you might be over your head.
 

dannac

Member
Joined
Mar 18, 2023
Threads
2
Messages
36
Now that you explained ... I must have the L-head engine.
When I remove the cover where the spark plug is, I only see the piston and 2 valves ... nothing to adjust. ( images above )

I would be over my head if I have to go deeper into the engine.

Thanks for reply.
 

Rivets

Lawn Royalty
Joined
Mar 11, 2012
Threads
60
Messages
15,357
From rereading this thread I personally doubt that your problem is valve clearance. If it had come to me I would have suspected an ignition or fuel problem. I would have started with checking for spark when hot restarting and if I had spark, I would have gone after a fuel problem. Just my opinion, but read my signature.
 

dannac

Member
Joined
Mar 18, 2023
Threads
2
Messages
36
From rereading this thread I personally doubt that your problem is valve clearance. If it had come to me I would have suspected an ignition or fuel problem. I would have started with checking for spark when hot restarting and if I had spark, I would have gone after a fuel problem. Just my opinion, but read my signature.
Haha .... your opinion on this issue is light years better than mine.

At this point guess I'll put it back together and give it another try.

The coil spacing was not equal ... would that have caused a starting problem ?
 

Rivets

Lawn Royalty
Joined
Mar 11, 2012
Threads
60
Messages
15,357
Yes. Did you read and follow post #30?
 
Top