Small chunk missing in SM465 case
 

Hi SM465 Experts,

I picked up a used SM465 transmission and NP205 transfer case to rebuild and install in my 72 K20. My currently installed transmission and transfer case are leaking, so my thought was to rebuild the recently purchased transmission/transfer case and just swap them out.

When I began to take off the items to gain access to the rear output bearing, I noticed a small chunk (less than a size of a dime) missing from case surrounding the bearing (see attached photo). No cracks noticed. I let out a string of curse words, but then paused to think maybe its still salvageable.

1. The chunk is high up in the case - well above the fluid level.
2. The transfer case housing surrounds the case at that point protecting it from the elements.

My biggest concern is that a crack may form causing the housing to fail.

Any thoughts on the matter?

Thanks!

Re: Small chunk missing in SM465 case
 

I think that's a bad thing. Oil will sling and it'll leak into the adapter.

Re: Small chunk missing in SM465 case
 

If there are no surrounding cracks I wouldn't worry about it as long as it seals up. Oil is going to get into the adapter regardless through the bearings themselves.

Re: Small chunk missing in SM465 case
 

I'd run it.

Re: Small chunk missing in SM465 case
 

I think it will be fine as long as it doesn’t crack out. The seal is on the input shaft of the transfer case so any oil that leaks will still be sealed from the transfer case and run back into the transmission. It’s certainly not ideal but it’ll probably be fine.

Re: Small chunk missing in SM465 case
 

Why not rebuild the current one you're running. I know it would be more work, but you could swap in the broke one for a short term fix while you rebuild/seal up the original. I wouldn't sleep well at night knowing I was running a broke trans., but that's just me.

Re: Small chunk missing in SM465 case
 

I'd fix it. Take the thing apart and tape off the inside then JB weld it up. Let it sit a few days to dry good. Put it back together and run it.:chevy:

Re: Small chunk missing in SM465 case
 

I agree with Tinman I would feel better rebuilding the current tranny in your truck and use the one you just bought to keep it running in the mean time

I tend to drive my 4x4 trucks hard I would be concerned about that break in the case leaving me stranded in the far back 40 or deeper could be a long walk home

Re: Small chunk missing in SM465 case
 

From the looks of that break the chunks inside , I'd toss it on the parts heap . :smoke:

Re: Small chunk missing in SM465 case
 

That bearing is no longer being held securely in place. That means the shaft is going to walk around causing extra wear.
If I were in your shoes, I would clean the area up around the hole including the outer race of the bearing. Then use JB weld (or other quality epoxy) to fill the hole and epoxy completely around the bearing to try to lock it in place. Once that is done i would swap the gear boxes and rebuild the one you're currently using and then do the swap again. Having the rebuild kits in hand before doing the first swap should reduce how long you have to use the damaged transmission.
Once that is done you might be able to sell the broken one for parts.

Re: Small chunk missing in SM465 case
 

For what it’s worth I did a complete rebuild on my 465 including vating and painting the case in 3 days time. You could easily do the same if you’ve got the parts on hand, the tools to do it( it does require some things not everyone has on hand, and the time to do it) by all means Id run your original transmission long term. That was what I assumed your original intent was.
You probably want to Get the gear bushings, they don’t come with most rebuild kits FYI.

Re: Small chunk missing in SM465 case
 

I would feel comfortable grinding the sharpest points off that, and using some kneedable epoxy to rebuild it.

It's not "load bearing" it's just a cast wall that keeps oil in its hole. Rebuild the wall and good to go. Would I do it on my truck? No, I'd get a new casting, but with a different budgets and time requirements, I would feel fine doing it if i had to.

Re: Small chunk missing in SM465 case
 

IMO, it's a bad casting. Like HO455 says, it's going to work until more metal breaks off. Toss it, that's my advice.

Re: Small chunk missing in SM465 case
 

I would not put a trans casting with a hole back in my truck unless it was survival related. I might of when I was much younger and needed date money, however!