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John Deere Engine Miss

Discussion in 'Mechanic and Repair' started by MBDiagMan, Nov 13, 2013.

  1. MBDiagMan

    MBDiagMan LawnSite Senior Member
    Messages: 852

    This is not related to a mower, but given the small engine savvy in this forum, I hope you guys won't mind commenting on the problem I'm having with my John Deere Gator 825i. I have a reasonable amount of experience troubleshooting EFI car and truck engines.

    This buggy has an 825cc. Chery, 3 cylinder EFI engine. It has individual coils on the end of the engine. There is no indication of a code being set, but although my scanner will connect to the connector under the dash, it turns out that John Deere has proprietary software so my scanner won't work.

    One month after the warranty expired, it developed a missing cylinder. I pulled the plugs and found the center one fouled. I cleaned it and the miss went away temporarily.

    I then used a stethoscope while it was missing and could hear all the injectors clicking normally. Although in my fifty years of messing with engines, I've only seen one spark plug that was actually bad, I swapped the number one and two spark plugs and the foul stayed with the center cylinder.

    I then swapped the coils between number one and the center cylinder and gave it a hard run. After it warmed up real good it began missing. I brought it back to let it cool before pulling the plugs and thought sure that I would see the number one plug fouled instead. It had been intermittently running well, and what I found was traces that the center cylinder had tried to foul, but couldn't confirm.

    I plan on giving it another hard run to see if I can get a consistent foul so that I can confirm which cylinder is now fouling, but at this point it appears that the center cylinder is the culprit even with the swapped coil, but remember, I have not totally confirmed this.

    Also, when running it at speed, when the miss develops, I get a popping and snapping from the exhaust, which seems to indicate that unburned fuel is making it into the exhaust and causing this.

    Any experience with a similar situation?

    Thanks for sharing your savvy and experience.
  2. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Think I'd be performing a compression/leakdown test before jump'n into the efi-ign part of it, You could have a tight valve which could cause "popping and snapping" out the exhaust after warmed up...... But adjusting these valves aren't as easy since they use different thickness shims.

    Compression/leakdown test cold then after skipping starts......
  3. MBDiagMan

    MBDiagMan LawnSite Senior Member
    Messages: 852

    Thanks restro.

    I'm taking a short vacation and probably won't get back to it until late next week. I think I might do a cold and hot compression test before running any more. I wouldn't want to toast a valve if it's too tight.

    Do you know a good source for valve adjustment information for these engines?

    Thanks again for your help!
  4. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Sorry...... I sure don't, Deere is kinda hush on what they share openly for free......

    You can check this board out; http://www.johndeeregatorforum.com/forum/forum.php

    I did see a couple Deere techs post'n on there that may be able to help......
  5. herler

    herler LawnSite Fanatic
    Messages: 5,139

    It's not a John Deere engine.
    John Deere doesn't make engines.
    They assemble the machines, I believe they manufacture the frame (which is to say, they weld the individual pieces together and powder coat it), and they might make one or two other bits but for the most part every thing their machines are made out of is manufactured by someone other than John Deere, they simply order it up and when they have all the parts, they run the frame down the assembly line where workers or robots attach all the individual components until they have a complete machine at the end.

    Just for example, the tires are probably made by Kenda.
    And maybe not but I guarantee they're not John Deere tires.
    Because John Deere doesn't make tires.
    And they don't make engines either.

    Hence it's not a John Deere engine.

    That having been said...
    I don't know nothing about this machine you speak of.
    But you brought it in here.
    Last edited: Nov 14, 2013
  6. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Thanks for the school'n herler......

    No one said that was a Deere engine...... :nono:

    Now it's your turn....... When Deere buy's engines from other makers they also buy the rights as well, This makes Deere the sole proprietor for that spec engine. They do this so end users have to go back to them for parts and repairs and why it's hard to find free repair info...... They want to SELL you a service manual, It's all about $$$$$$$$

    To prove the point, I'm a Kawi engine dealer and can look up parts and repair manuals for any engine on my dealer's site......EXCEPT Deere spec engines......

    Also, Deere is known to have engine makers spec engines for them only therefore some parts from a non Deere spec engine will not interchange......
  7. MBDiagMan

    MBDiagMan LawnSite Senior Member
    Messages: 852

    Yes, the engine is made by Chery in China:rolleyes:(explains alot) and is a model number 372.

    Again, I appreciate the help. When I get back from vacation I'm going to do a cold and then hot compression check. If it does indeed have a valve too tight, I don't want to run it much for fear of burning a valve.

    If it does indeed appear that there is a compression problem, I will figure out how to remove the cam cover and check valve adjustment.

    I will post a conclusion whatever it turns out to be so that maybe it can help someone else along the way.
  8. MBDiagMan

    MBDiagMan LawnSite Senior Member
    Messages: 852

    I did a cold comp test this morning. Got up to 190 on all cylinders. Ran it a few miles, the miss developed. Checked while hot and got about 180 on one and three, but only a little over 150 on number two.

    I guess it's time to find valve adjustment specs.

    Thanks very much for putting me onto this Restro!
  9. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    I get lucky sometimes...... ;)

    I've seen a couple new Chinese single cylinder engines that would shut down a few minutes after starting, I found tight valves......
  10. MBDiagMan

    MBDiagMan LawnSite Senior Member
    Messages: 852

    I can't find any tech info on this engine. I am going to remove the cam cover and see what I find. I should be able to use feeler gauges to determine what the valve clearances on the other two cylinders are and then see if I can set the center cylinder valves to match them.

    I don't know until I look at it, but maybe the adjustment will involve removing a shim rather than adding them. If not, I'll try to find the shims.

    I hope to get to this on the weekend.

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