Forum Discussion

Snowman9000's avatar
Snowman9000
Explorer
Nov 06, 2016

SOLVED: look at your Onan 4K genset for me?

EDIT: Never mind my request for you to report the orientation of the part described below. I now believe it does not matter. I will continue to update the thread re my troubleshooting findings.

FINAL EDIT: Solved. It was adjusted too lean from the factory. In this condition, the coil will hang/stick until you pull on the rod by hand. Once I adjusted the setting per the manual, it works fine.

ORIGINAL POST:

If you have modern Onan 4KY gas genset, can you look at the choke adjustment disk as shown in the photo below, and report if the adjustment lines are on the left side of the circle, or on the right side like mine in the photo?

I'm having a problem with something inside that housing hanging up. And it's not the rod hanging up on the hole. It's something inside. Both the service and parts manuals show the notches on the left side. So I would like to hear where your lines are. Maybe my disk is installed 180 degrees off, and maybe that is causing the sticking. When you read the adjustment procedure, it makes NO sense that the holding nut would be covering several of the lines. Thanks!


  • Snowman9000's avatar
    Snowman9000
    Explorer
    Nov 07, 2016
    Linkage was free this morning. Yesterday afternoon an hour after the run, it was sticking lightly. So it released overnight.

    I think because the factory setting was too lean (too far clockwise), it let the end of the coil element get too long and it wrapped down around the coil and got stuck behind it. I am going to try it again. If it works the next time, I'm done messing with it.
  • CloudDriver's avatar
    CloudDriver
    Explorer
    Nov 07, 2016
    Snowman, Since you asked for a picture, here is one I took a few years ago for a post. The setting of the disc is about the same as yours and is as set by the factory since I have never made any adjustments or taken it apart. Our RV is in the driveway, so I went out to take a fresh look. Still the same as the picture. I moved the rod from the choke end and noticed no binding. I did notice that when I pull the rod toward the choke the rod moves from the center to the top of the hole. From your picture, the rod is at the top of the hole when cold. Just a guess, but perhaps that is the cause of the binding.


    In case it helps, here's a picture of the choke end that shows both a side view and a reflected top view in an inspection mirror.
  • j-d's avatar
    j-d
    Explorer II
    Nov 07, 2016
    I went out and looked at ours. The right hand edge of that notch in the disc is close to lined up with that little hole. This puts the pinch nut over the second mark from the left hand edge of the range of marks. Yours looks to be pinched at about the third mark from the right.

    Might be only how your picture is taken, but it looks possible to me that the linkage rod could be rubbing inside that fluted guide. Ours appeared to be above the center of the hole, but not as high as yours.
  • Snowman9000's avatar
    Snowman9000
    Explorer
    Nov 07, 2016
    Harvard,
    I'm still tinkering, which includes more run cycles because it only binds after it gets hot. Preliminarily, I feel that adjusting it richer (CCW- counter clockwise) will lessen and maybe cure the problem. But I should have something to report before you use your MH again.

    You are supposed to set it by loosening the disk, then rotating it till you see the linkage in the view hole. (Which is darn hard to see.) Then turn it one mark CW for every 10 degrees you are above 70 degrees, or CCW for every 10 degrees you are below 70. Then tighten it back up. I set mine today; it was about 2 marks too lean from the factory. With the richer setting the post-cool down binding did not seem as tight. I'm going to see if the shaking from cranking the engine is enough to knock it loose now that it is adjusted properly. If not, I'll go one mark richer and then see. I also plan to call Onan.
  • Harvard's avatar
    Harvard
    Explorer
    Nov 06, 2016
    The way I adjusted my thermal spring was to set the choke just closed at a normal summer day (about 60F) with the spring at OAT. The choke still locked up choke open when full hot after it cooled down.
  • Harvard's avatar
    Harvard
    Explorer
    Nov 06, 2016
    Sorry, my unit is at a remote storage facility so it will be awhile for me to make/capture any observations.
  • Snowman9000's avatar
    Snowman9000
    Explorer
    Nov 06, 2016
    I believe the metal coil element is going overcenter as it lengthens.

    Here is the inside of the adjuster, from an ebay listing. The orientation of the prongs is not going to affect anything.



    Here is a picture of the element.



    I rotated it and added a line to mimic the rod going to the choke lever. The coil expands as it warms up. It lengthens, and the end of it moves to the left in the photo, pulling the choke rod. So that end is either continuing to wrap around the circle and then getting stuck as it cools, or the tab sticking up is catching something. Or the little cover no. 11 shown in the parts drawing is catching something.

    I'm going to get my MH into my workshop later this week. The choke is stuck open now. I will get something figured out.
  • Snowman9000's avatar
    Snowman9000
    Explorer
    Nov 06, 2016
    That is exactly what is happening with mine. I intend to get to the bottom of it.

    The way my previous Onan acted, it may have had the same problem.



    Looking at the tab or tabs on the center of the disk, there could be some directionality problem if it is installed 180 degrees off. So Harvard, which side are the adjustment lines on on yours?
  • Harvard's avatar
    Harvard
    Explorer
    Nov 06, 2016
    That housing contains the thermal spring for setting the choke based on the temperature.

    In my case, this thermal spring goes to a full hot position when the gen warms up to operating temperature AND THEN HANGS UP there. So during the next cold start cycle the choke is stuck in the full open (non choke) position and the gen set will not fire up.

    I have fiddled with this for years to no avail. So, I have just gotten used to manually dislodging the stuck spring when cold so I have some choke applied before I try to crank it over.

    I too will be very interested if someone knows the secret to this problem.

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