Hey guys I'm having a bit of trouble with my rear main seal on my 98 sidekick sport 4x4 with a manual trans (USA).  When I got the sport it had a slight oil leak, not severe enough to leave puddles but enough to coat the whole transmission, driveshaft, and  cross member.  The leak slowly got worse over a year of driving the trucklet, to the point where a decent size oil spot developed where ever i parked.  After talking to a friend of mine he suggested the rear main.  I picked up a replacement seal and we got to pulling the tranny and replacing the seal.  Needles to say this job was not thrilling took about 4 hours more then it should do to a pesky wire preventing the engine and trans from connecting. Thought this would be the end of my troubles but after a few thousand miles, good wheeling, and a vaccation trip the seal is now pouring worse then it ever has. 

Any how this brings me to my first question.  I recently read that there is the seal AND a gasket on something that mates near the seal?  We only replaced the seal and didn't see any old gasketing. After we removed the clutch, flywheel, and pressed in a new pilot bearing it was time for the seal.  Took the old seal out and used it to tap the new one in and put Cooper rtv to seal it.

Is this mystery gasket I read about what we missed, in addition to the seal it self?  I've been desperately trying to find an answer as the leak is now the worst its ever been; can loose a whole quart over a small trip.  I wish it was as easy as a distributor o ring but the sport model does not have one? 

Are there any locations on the back of the engine that are notorious for leaks?  I've cleaned the engine/ tranny to see the leak after a drive and only ever see it pissing from the bell housing after shutting the engine off.  Is there a way the engine has some deformity in the seal hole?  In desperate need of some advice or help.

Thanks for any advice or help guys- Mark

I'm pretty sure the 1.8 does have the equivalent of a "distributor O-ring" - in the base of the cam position sensor - I can check the parts manual in the morning, but I don't think that's the source of your leak - if it was you'd see the trail of oil above the bell housing also. 

Really? Hmm I'll probly replace that as well just to be sure and im sure its not to glourious after 10+ years.  I have a friend who has been building open wheel modified race cars for years.  Im going to ask his opinion and any one on here with some knowledge of it. 
Is there any kind of race product or mabey just at the regulars (autozone n such) that is an rtv or some kind of silicone that could withstand the conditions under there?  At this point im thinking I should get the new seal, press it in and then use enough of a very high grade rtv to cover the entire face of the seal?  And i mean really covered so there is no question.
If I go this route after finding the right type of sealer anyone think this will interfere with any thing?  From my last look there should be some space in there between the block and clutch where the rtv cld rest with out being sheared off by the clutch.
Does that seem correct to any one about the amount of room i have for rtv?

I took a look at the parts catalog, there definitely is an O-ring on the cam position sensor, I also didn't see anything else in behind there (other than the rear main seal) that would leak the volume of oil you seem to be describing.

Regarding RTV on the seal - it would depend on where it's leaking from, and you'll have to drop the transmission and do a thorough clean & inspection to determine that - the seal works by having a thin lip constantly rubbing against the rotating crankshaft, with a circular spring behind the lip to maintains the required contact - if that spring becomes dislodged or the lip damaged (both fairly easy to do during installation) or the sealing surface of the crankshaft scored - you will get a leak through there - RTV will not help.  It is also possible to have oil leak past the outer edge of the seal and a thin smear of RTV on the outside of the seal when installing it can help with a leak here.

Did you use a tool to get the correct depth of the seal? Does anyone know about this mystery gasket I've heard about?
As in not the seal itself but some type of gasket for around the seal, believe its a 2 peice gasket.  Im really trying to avoid doing this ever again let alone a few thousand miles after changing it again.  Now that i know the seal should not be pressed all the way in makes me feel the correct tool is almost a nessicity.

Are you sure this "mystery gasket" applies to your engine?  The G16 engines used in the base SideKick have an oil seal housing with a gasket, that the rear main seal fits into, the J18 engine used in the SideKick Sport, does not.

I've never changed the rear main on my engine, although I may do that next week - I have to change the clutch, and I picked up the seal this morning along with the rest of the parts I need, but Wether or not it gets changed depends on what I see when I get in there - the FSM does show two special tools to be used to install the seal but I have no idea how necessary they actually are.