The Stovebolt Site Forums The Shop Area Driveline ? Gearbox leaking into torque tube

Hi folks,

Is there any external indications which would show the gearbox is leaking into the rear differential

I ask as I am chasing lots of oil leaks but biggest one was I found my 3spd synchro gbox was empty of oil, well it was level with the drain hole, got some oil leaks around front carrier gasket in the diff but the oil level was pretty close to full

Sorry forgot,

216 engine
3spd synchro box
Torque tube rear differential

If the driveshaft seal behind the gearbox is leaking, the rear axle will eventually be overfull, and the transmission low.

Most likely the axle seals will leak when this happens and your brake shoes will get soaked if left to long

Nice, thanks for that, want sure if it was a possibility or not

Simso - You mentioned when you checked your transmission fluid level it was at the bottom of the "drain hole". Did you mean the bottom of the fill plug hole, located on the side of the main case???

If in fact your checking the fluid level from the side of main case fill hole, and the fluid is even with the bottom of the hole, it's exactly were it's supposed to be and you have all the lube you need in there and haven't had any migrate anywhere else.

Perhaps you could post some pictures of your 3 speed and the "hole" you are getting you fluid level from so we can offer better answers to your question please?

Check the rear axle gear oil level. You may find where all of your transmission gear oil went. There is a seal in the torque tube to prevent this, and an Okie bushing/seal to fix it.

Not my photo, grabbed it from eBay but I circled the drain hole where the oil level was just below

Yes, that's the drain hole and if the level was below it, then the tranny fluid is empty. It should be just below the upper plug in the photo when full.

Yeh I filled it up yesterday, going to take it for a short drive tomoz and start trying to find the oil leaks.

Dont get me wrong long term swapping it out, but have not been able to find a Saginaw pattern t5 here in Australia

I have a transmission bellhousing that will fit up to the 216
I have a 57 chev rear end open drive sitting in the shed, pretty much straight bolt in
I have a 57 Chev tailshaft will need to be shortened to fit t5
Just need the box, clutch, and everything else

Wow, I don't see how the gearbox could still be running if the oil level is below or anywhere near the (circled) drain plug. When I check mine, I stick my finger into the upper plug hole and bend the finger downward to touch the oil. This would be about 1/2" below the upper plug hole.

So cleaned my gearbox down spotlessly after filling, let it sit for two days on the hoist, have found a static leak, just above the drain plug, looks like I may have a cracked box

Someone may have overtightened the drain plug. It's got tapered threads and could crack the case if overtightened. It may be possible to stop drill the crack and braze it shut. Or maybe seal it up with JB Weld. To do that you'd need to completely disassemble it and clean it, but the best bet would be to replace the transmission. Might be a little difficult to come by in Austrailia.
If you can, clean the outside of the transmission with brake clean and take a photo, so we can see how serious it might be.