Oil leak on bottom side of bellhousing

[aeontony]

I figure I should probably get some advice on what it might be before I rip the transmission off..

On the bottom of the bellhousing where it connects to the engine, there is a little rectangular hole. I figure it's either to release pressure, or to drain oil if there's a buildup. Mine is leaking oil out the hole. I can't tell if it's engine oil or transmission oil. It doesn't quite behave like engine oil..if engine oil leaks onto the ground slowly there would be a tendency for it to pool and spread in a circle. It almost looks like water, the way it's spreading and attaching itself to the ground, but I'm sure it's oil.

If it's engine oil, that would mean my rear mailn seals are going..they are brand new since the engine was rebuilt, but there's always the possibility that they were not installed correctly. What are the symptoms if the engine is leaking oil out the rear main seals? Would there be a difference in clutch engagement, for example?

Or my transmission could be leaking oil out the area near the connecting shaft. I have no idea if this is possible.

Does anyone have any idea what it may be/what I may do to fix it?

(ps: I think the transmissions/engines layouts are pretty much the same with regard to seals, etc. Let's just say that it's an sr20 layout.)

[bshotts]

If the substance you are leaking is indeed oil, which if it's brown and thick it most likely is, then it could either be your valve cover, factory oil cooler (where your oil filter screws on), oil pan, front or rear mail oil seals in increasing order of difficulty to diagnose IMO.

I am guessing you have an SR maybe Redtop because I have read these are notorious for leaks from the front main seal. At any rate, I would clean all the oil off the block you can, then run the engine for a couple minutes to allow some oil movement. Just make sure you let it cool down some before you touch the block or oil!

Check all the way around your valve cover especially near the firewall. It's basically impossible to see how the half-moon shaped area of the valve cover gasket is sitting on the head at the firewall, but you should be able to feel how it's seated and if any oil is leaking. If it is, you need a new valve cover gasket if worn down, or to adjust the one you have so it sits properly.

Also, look around your oil pan and oil pan plug as those leaks can be pretty obvious. Pan might be dented, cracked, plug might be tweaked in the threads of the pan.

Next, look around where you oil filter is to make sure it's not dripping from there. Be sure to look around the front cover of the engine and see if your block is getting oil on it. If it is, you most likely need to reseal it (per FSM) using lots of blue RTV or possibly even install a new front main seal (per FSM). My money says it might be this if not the simpler reasons as I have had to deal with a leaking front cover before. Just make sure to let the RTV set long enough to withstand the oil and to torque front cover bolts per FSM.

You have to remove the transmission from the block to actually get to the rear main seal, so hopefully you will have found it before then. Also, I had a small drip from the back of my Redtop where the OEM oil catch can oil/air separator is from the inlet hose. Make sure your connections there are good if you do have this setup. Good luck, and have patience!

[aznpoopy]

dip your finger in the oil
smell it

tranny oil smells horrendously bad. if its leaking from the bellhousing, you need to pull the tranny off and redo the front seals and gaskets on the trans.

if its engine oil, you need to pull the tranny and flywheel off and redo the rear main seal.

[ManoNegra]

I can't tell if it's engine oil or transmission oil. It doesn't quite behave like engine oil..if engine oil leaks onto the ground slowly there would be a tendency for it to pool and spread in a circle. It almost looks like water, the way it's spreading and attaching itself to the ground, but I'm sure it's oil.

Check you brake and clutch master cylinders aswell, they could be leaking and brake fluid has that watery consistency.