I recently swapped my 94 Accord EX Wagon from automatic to manual transmission. Before the swap it was leaking ATF from the passenger axle seal and engine oil from the engine/transmission interface. The engine oil was only a drop or two, so I didn't take much effort to investigate the source.

After the swap the car seemed leak-free for the first couple thousand miles. However things went south and "oil" started leaking out from the engine-transmission interface. There are many threads that point to the rear main seal, but I would like to know if the transmission input shaft seal could be the culprit as well. P. Adams pointed out in a post that the transmission is not pressurized, and that a leak from the input shaft seal could only happen if the transmission was "grossly overfilled."

When i swapped the manual transmission in, I noticed the inside of the clutch housing was caked with grease. The clutch disc and pressure plate were both clean. I figured the grease was from the donor car's rear main seal. I also taped this hole on the transmission, supposedly the breather hole, because I was drilling a new hole onto the transmission mount and didn't want any shavings to go inside the hole. I forgot to take the piece of tape off, and am thinking if THAT could cause MTF to leak.

Is it the rear main?, or the transmission? Any help is appreciated. This project has been quite expensive, and the wagon's at the shop awaiting yet another transmission removal. I thought Hondas were supposed to be trouble-free. Thank you in advance.

 

Honda's are trouble free when you do the required maintenance. That includes changing the rear main seal, and oil seals at the required mileage, or when your car is pulled apart, might as well do it, because it will be just as much work going back to fix something that you could have spent an extra $15 or so in seals and change while it was pulled apart. I do not have in dept knowledge about which seal might be leaking in your case, but I guess it does sound like it could be the rear main seal. I went ahead and changed all my seals accessible when I did my clutch, and also changed all my seals accessible when I changed my timing belt/water pump. I found that my balancer seal was leaking.