I bought an NOS 684089 muffler kit on Ebay not too long ago, and when I went to install it, I realized that the holes for the short bolts have no threads. The bolts are not self tapping, either, so they wouldn't even begin to go in. Are there supposed to be threads in the holes? Being an NOS kit, all the hardware is original, so I'm lost. I guess I'll have to tap the holes to make it work. Has anyone else had this problem?
That's one strange Lawn-Boy muffler. Could we get a model off the mower or engine type. It doesn't look like a D series muffler or even an F series muffler.
The D and F mufflers were donut shaped, actually round.
The mower in question is in my signature. The muffler shown is a late-model part used with F Series engines and BBCs, just like mine has. I'm replacing the original circular steel muffler, what I commonly call the donut.
Everything goes together from the bottom, under the deck. I'll grab a tap at work and take care of it. I don't know if it was a QC slip up or if this is actually how they came. I just find it hard to believe that this kit would be sold this way.
The muffler for your engine is no longer available and has not been superseded. I don’t know if the one you bought off evil bay will fit. My guess is no, without seeing your entire unit. I suggest you contact Lawn Boy with your problem either by phone or email and see if they can help. This website might help. https://www.lawnboy.com/en/customer-support/customer-inquiry
The muffler fits my mower as I've already bolted it on. The issue is that, per the instructions, there's no way to assemble the gaskets, heat shield, and cover because there are no threads in the bolt holes. I was just wondering if anyone else has ever had this problem. I find it hard to believe that Lawn Boy would have sold a part that missed a vital machining step, but anything's possible.
I'm pretty sure your muffler assembly was designed to use self-tapping bolts. I think you did fine by tapping the holes and installing regular machine bolts. I'm not a fan of those self-tapping bolts anyway. I would strongly recommend a good thread locker for those bolts though. I was looking at the IPC for your model from around 1984, and wow what a machine! I bet that mower cost a pretty penny back then.
