And first off I'm stoked. Its a 1973 CJ5 with an AMC I6 258 Dana twin stick and the PO was an engineer who just wanted something to tinker on, barely even drove it. Whole laundry list of new parts, etc.

So we hook it up with a tow bar and drive it 80ish miles home, made sure it was in neutral and both sticks were also in neutral. I get home and take it out for a spin, drives great. Pick up my brother, he drives it for about 15 minutes, we park it back at his place and check it out, pop the hood, looking at everything and he says "hey you have a hole in your motor." Sh*t. Sure enough, theres a golf ball sized hole in the bell housing just behind and above the starter. I crawl underneath and the front plate is also bent out, but the fluid buildup on the bottom of the housing is definitely not new, and not splattered everywhere. It was most definitely not there when I inspected and drove it in Denver, must have happened when we were towing.

Can anyone tell me what I'm looking at here? It looks like it was blown from the inside, but it drove fine despite the hole and lack of fluid. Did a bump in the road pop it into gear and shred something? Is this a patch and fill job or do I need to start looking for new parts?

Attached Images

     

Time for a 350/sm420!!!! But I guess take the transmission off, find a new bellhousing, front plate and whatever else. Hopefully nothing internal in the tranny got messed up. Start by taking it apart and go from there.

Cool project. Don't get discouraged, it will be well worth it in the end. As said, take it apart and see what is needed, replace as necessary. They are pretty straight forward to work on. Looks like a really neat Jeep.

Thanks for the quick replies. I've never dropped a transmission before but thankfully on this old Jeep it doesn't look like anything too crazy. Only one way to find out!

There shouldn't be any fluid lost from the bell housing since there isn't any fluid in the bell housing itself, the old fluid/oil on the bottom is from either the rear crank seal, rear oil pan seal, or gear oil from the front transmission seal, it could even be from valve cover leaking and running down to the bottom, my guess is it's oil from one of the first seals I mentioned.

The hole is a mystery until you get it apart, the only things inside the bell housing are flywheel, clutch and pressure plate, and throwout bearing and the fork that holds the throwout bearing, it's possible that a pressure plate bolt came lose while driving it, or a bolt from the front of the transmission input shaft housing and slung outwards and smashed the hole in the bell housing, the only other bolts in there would be the flywheel bolts but they are behind the clutch plate and it would be hard for one of those the get slung outward and cause such damage.

The engine should be fine other than a possible oil seal as mentioned.

If you do find that a bolt came lose just replace it with a proper replacement, the hole in the bell housing will not affect anything and you should be able to run it with the hole with no problems after the repair/replacement to whatever caused the hole.

Thank you this is exactly what I needed. Do you think I can get that sucker down with a regular floor jack or should I shell out for a transmission jack?

Transmission jacks are nice to have but with a manual transmission a floor jack will work, just a bit harder to keep it balanced on the plate of the jack and moving the jack the way you want it to go trying to get straight in at the back of the engine, transmission jacks have a large plate with chains to secure the load on them and casters wheels on all 4 corner so it can move easily in all directions.

That being said in my younger days every manual transmission I ever removed or installed I didn't even use a jack, never had a transmission jack or a floor jack for that matter back then, I always just use my arms and just sorta bench pressed them in and out, lower it down on my chest and then slide off to the side, most manuals don't weight all that much compared to a automatic.

I'm not as young as I was once was but I have no doubt I could still remove and install one without a jack but a floor jack will make it much easier if you keep the balance correct.

Thinking a bit more on the hole you have it could also be other parts of the pressure plate as they have springs in the pressure plate but I would still think a bolt most likely could be the what cause the hole, it could also have been cause by a rock or similar being throw at the bell housing by a tire,

Thank you AuSeeker great info! I had time to pull the starter today and found the gear had split in half, only found one half and some shavings, so I'm thinking the other half might be behind the hole in the bell housing. Prepping to drop the transmission and get this patched.

Yes that half of the gear would for sure being banged around from the pressure plate and flywheel rotating at high speed be the cause of that hole, I wouldn't be so worried about the hole and you could leave it as is if you so choose and have no issues at all...but I definitely inspect the back of the engine block, pressure plate, clutch, throw out bearing and transmission input shaft housing for damage from the piece of gear being banged around in there, this would be my biggest concern, the hole not so much!!

Wouldn't it be bad to get trail debris or moisture in there? I might just cover it with some metal duct tape if thats the case for now. Although I do have a friend who can weld aluminum so patching would be easy.

Yes stuff could get in the bell housing when off roading, but unless you find what appears to be a structural issue at the hole I would just use JB Weld or similar metal epoxy to fill the hole.

Some JB weld or similar would easily plug the hole for you. It's not really a structural spot, so real strength isn't an issue. Or a decent welding shop could plug it, but its cast, so welding is a bit more difficult.

Thanks for all the help, hole is patched and she's running great!