I have an Onan genset (HDKAU), with an isolator bolt problem. One of bolts keeps falling out - it can't be tightened anymore, as it's skipping in whatever it's supposed to be screwed into.

Based on the parts manual, and visually inspecting what I could see (last time I had it out), the bolts are screwed into the flywheel housing (2) and into the oil pan (1). I ordered replacement for both, but as they have arrived, I see there are no threads at all in any of the holes that the bolts are supposed to go into.

I would really like to avoid having to remove the genset from the van it's in just to figure out what am I missing. And to figure out what's up with the female part, whatever it might be, I'd have also at least lift the engine block up (hence I don't have any actual pictures). All of this isn't at all a quick job, so I'm trying to have all the parts I might need on hand once I go in.

Here is the picture of the (bolts 3 go through isolators 2 and then would screw into oil pan and flywheel): isolators and the bolts

And neither the oil pan (the ear on the front left side):

oil pan

Nor the flywheel casing (12): flywheel casing

show any parts that would receive the bolts.

So, what exactly are those bolts supposed to be screwed into?

  • 1
    Could you provide photos?
    – Martin
    Aug 31 at 7:25
  • A guess; those three bolts thread into the engine case and bottom out while allowing the rubber isolators to absorb engine vibrations. Wear and tear stripped threads in one hole of the engine body. This may present a problem of whether or not a heli coil can replace stripped threads. Unfortunately, removing the engine would be required for access to the stripped threaded hole unless the rubber isolator is removed to view the area with a mechanics mirror to determine if repair is possible.
    – F Dryer
    Aug 31 at 22:52
  • @FDryer Yeah, the problem is that the replacement parts have no threads. The bolts haven't come yet. Once they do, maybe I'll see that I have to cut the threads in myself, that'd be fine. Aug 31 at 23:19


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