Thread: Transfer case drain bolt

Originally Posted by Bigbjorn

Head size is not how you express fasteners. Diameter and pitch should always be used. Head size is meaningless as manufacturers often have non-standard heads. Toyota, honda, Kawasaki use some almost unavailable threads like 9mm & 11mm & 13mm to lock you into their overpriced parts system.

All very well but the O.P. used the only measurement available, head size. An experienced internet warrior knows this sort of thing automatically.

Originally Posted by poida

That’s right.. probably could have worded it better.
It isn’t a 1/2” square drive, the fill for the transfer case is.
On mine it was a 17mm bolt with a copper washer. And the bolt snapped while removing 🤢

No worries, the few I've worked on were taper thread plugs with a recessed square drive.

I have measured it but can't recall.

If uninformed is back today I'll get him to check as he has a couple on the bench atm.
Nor sure if he has a pitch gauge though?

Probably find the reason it snapped was someone had forced a parallel threaded bolt into a tapered thread hole.
Aren't they a BSP thread?

Originally Posted by donh54

Probably find the reason it snapped was someone had forced a parallel threaded bolt into a tapered thread hole.
Aren't they a BSP thread?

Don, do you reckon it's the same as the diff fill plugs?
If so I have a couple here I can measure.

Originally Posted by bee utey

I'm told you can use a left handed drill bit to pilot drill the plug, and if you're lucky it just unscrews with the drill. Even a right hand drill bit could get it moving, just be careful it doesn't go inside. Not that taking off the bottom cover plate is very hard.

Using a reverse helix drill usually works well. However if it is really jammed in and the drilling thrust does not shift it, do NOT use an Ezy-out as if you break one of these off in the stud then you are in trouble. A HSS drill will not dent an Ezy-out. You can drill out a broken Ezy-out with a solid tungsten carbide drill and these are expensive.

I'm thinking that if a 17mm socket has snapped the damned thing an ezy-out or LH drill bit won't have a chance at moving it.

I haven’t tried yet to get it out.. I do have ezy outs which I was going to try. The bottom cover gasket is weeping anyway so if I have to take that off and replace the gasket it won’t be the end of the world.

Just use the level plug to get your measurement,unless the drain has been re-tapped, they're the same.