Oil leak 2004 R1150RT

My 2004 R1150RT has 30K miles with good care and modest riding. Synthetic oil was first used at 8K miles and continued to present. A very small oil leak was discovered at 28.5K, estimated at one drop every three days while parked and now about two or three drops per day. The oil is running down onto the bottom of the exhaust assembly chambers where it drips into my small cup. With panels removed, I see oil wetness above the exhaust assembly and some forward of this. Both cylinder heads are dry all around. No oil around filter cavity or on filter. No oil around oil drain plug. No oil around left cylinder or fill plug. Most, if not all, oil wetness is on right side of engine, even on fuel lines/connectors above intake injectors. Leaked oil color and viscosity appear to be engine oil. A leaking/seeping rear main seal comes to mind. Any other ideas much appreciated before I take the bike to a new dealer I've not traded with before. Many thanks. Dick Francis.

It does sound like a crankshaft main seal to me. Clean around the round hole in the bottom of the bellhousing and see if that isn't where it is dripping from.

A rear main seal leak will go into the bell housing and then drip from this drain hole.

Could it be the donut that seals the spark plug?

There is a "home brew" method to finding leaks.

Lots of auto tranny fluids have dyes in them already. A blacklight, the kind kids used while smoking the other leaf, lights the dye up pretty damn good.

My only caution is to find tranny fluid with the dye and then change the oil right after, usually when you do the repair.

PAS said:

Could it be the donut that seals the spark plug?

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not very likely.
those donuts tend to leak profusely when they do.
OP indicated no oil around are of heads- a leaking donut would leave residue all over heads, barrels, etc.

dieselyoda said:

Lots of auto tranny fluids have dyes in them already. A blacklight, the kind kids used while smoking the other leaf, lights the dye up pretty damn good.

My only caution is to find tranny fluid with the dye and then change the oil right after, usually when you do the repair.

Click to expand...

This will help differentiate between engine and transmission oil.

My tried and true method for oil leaks doesn't do that differentiation very well but it does find leaks. I clean every suspect source thoroughly and then spray the area with anti-perspirent - the white powdery kind. When oil again seeps it turns the powder brown, and fans out. It leaves a little arrow shaped marker aimed right at the leak.

If you have oil dripping from the bellhousing drain hole and then remove the transmission, it is usually very easy to tell if it is coming from the transmission or engine.

Transmission oil will leave streaks on the back side of the clutch cover. Engine oil will leave traces on the front face of the clutch housing (flywheel) or running down the engine case.