Missing drain plug?

[snowsurfer56]

[IMG][/IMG]1999 Monaco Diplomat, Allison 6 speed auto trans.
Had my oil changed recently, was under the MH and noticed this threaded opening.
What is it? What drained out of there? Why does the MH seem to drive ok?

[Old Scout]

...its most likely the drain hole for the tranny bell housing--no plug required!!!! if you had a main seal engine leak or a tranny input shaft leak, or perhaps a converter leak, this is where you would see the leak....

[snowsurfer56]

It is on the bell housing. Why is it threaded?

I posted pics. Not showing in post.

[snowsurfer56]

Thank you

[Gary RVRoamer]

There doesn't appear to be any image source referenced in the IMG tag in your message. At a guess, you may have tried to use an image that was not somewhere that the IRV2 editor could link to for a reference. That's what the image icon on the Quick Reply screen does. If you want to include an image from your own pc or phone, use Advanced rather than Quick Reply and Attach the image (paperclip icon).

[twinboat]

Its threaded for other applications, like deep water driving and construction equipment use.

[YC1]

I panicked a bit years ago when I first discovered the threaded hole. Normal setup.

[Old Scout]

...some applications for diesel engines require a remote or isolated drain for the bell housing --like maybe a stationary generator in a eco-sensitive area....so you would attach a threaded pipe to the bell housing to divert any fluid leaks to a safe or more visible/accessible location--but that's only a guess.....

[Mr_D]

Worried me years ago when I discovered it. I happend to be at an Allison shop to get a rear main seal done on the trans under warranty. They assured me it was normal.