Oil Leak in 1996 GTX

[Lothsahn]

Still chasing the oil leak(s) in my 1996 GTX.

After I run the ski and let it sit in my garage, it leaks about 1/8 of a cup of oil into the hull. I've chased and fixed the following leaks:
Gasket at the bottom of the oil tank (the red plastic fitting is now dry and paper towel shows no oil on the black mat beneath the fitting on the hull.
Gasket at the top of the oil tank (it used to have dried oil residue all over the oil tank. Replaced the gasket around the oil return and now the top of the tank is dry and clean
Crankcase oil fitting - The screw clamp fitting on the oil line where it goes into the engine block behind the starter was loose and could be spun by hand. Found oil leaking from around the hose. Tightened the fitting and leak seems to have stopped and I can no longer spin the fitting.

I've checked the lines and I don't see any cracks or leaks in the oil lines themselves anywhere. The oil line rubber is pliable and in good shape. The top and sides of the oil pump look fine, and the two small lines from the oil pump to the cylinders look intact and in good shape.

At this point, I'm thinking there's either a leak in the tank I can't see (but it should be one piece, given it's a 1996, right?) or a leak from the block or the oil return line from the block. Unfortunately, the exhaust piping completely blocks any ability for me to see any of that.

How should I proceed? How do you get to the oil return line without pulling the exhaust or the engine?

 

[etemplet]

Clean the entire bilge. Get white paper towels and fold them at least double. Place them under the leak paths. You'll be able to locate the source. Place one under the oil tank and along the oil pump feed line and under the oil pump. Place one under the rotary valve where the oil lines connect to the rotay valve chamber. Place a towel on the left side of the engine where the high level oil line comes out of the engine. Wipe down the oil tank as best you can, get it really clean and dry. I think you'll find your leak. Good Luck !!

 

[Lothsahn]

Good feedback, but I already kinda did this. The oil just keeps coming back, invisibly. No oil under tank or oil pump feed line. Will do what you suggested with the rotary valve and the high level oil line.

I'm afraid it's from the return side connect to the block but there's no clearance to work on that side at all...

 

[etemplet]

I had a problem oil leak when I used a non-standard oil line as a return. No matter how much I tightened the clamp it still leaked but it was difficult to detect. One drop every 10 minutes can add up over time for sure. leaks are generally where you can't see them or are difficult to get to.

Check this one out that i found on a ski I was working on. I noticed a valve on the oil feed line to the rotary valve which usually means the crank seal is leaking. After looking inside the engine I didn't see any visable oil which is a good sign, I did a pressure test.

Rotary Valve Parting Leak Video