Hey friends, Happy New Year to all. Need some help!!! A friend has an 05 Road King with an oil leak at the outer primary cover right below the drain plug. The first thing we did was replace the gasket, but it didn't help. Next, we cleaned the gasket and the cover, and used silicone sealer on both sides of the gasket, and it still leaked. Finally we removed the gasket again cleaned it again with carb cleaner and used shellac to glue the gasket to the inner and outer primary covers. We let it dry for three days before adding oil to the primary, and it still leaks a little bit. Maybe three or four drops a day. The only place where it's wet is a two inch spot right under the drain plug. We checked the drain plug and it's not leaking there. I even torqued the primary bolts by the book. Hope someone has a suggestion because this is driving me nuts. Thanks

 

Sounds like an inner primary bearing seal leak.

That often runs down the back of the inner primary, and runs to the low point to drip, and looks like a leak from the outer primary.

 

If the leak is not from another location & is flowing to the lowest point which is at the drain plug. It's possible that an internal crack has developed in the drain plug boss. Sometimes this crack will only leak when the drain screw is installed and the fluids are hot, due to thermo expansion of the crack.

You'll have to remove the primary cover & clean it to inspect for a crack like this. A magnifying glass is very helpfull. No easy detectiion or fix and often only something like JB Weld or epoxy will fix it.

You could try a new drain screw with plumbers paste as well.

 

you can track a leak by spraying the area with drugstore foot powder.

the leak will wash away the powder at the source.


2.) the modern HD primary gasket is thin and barely compressable -
If the covers are warped ( like by not "I even torqued the primary bolts by the book", it is more than possibly to warp the covers by unevenly tightening the bolts) you'll have leak problems. -esp if the owner has not paid attention to torque specs in the past

the aftermarket still sells the "paper" type primary gasket which has the ability to conform to irregularities- that's what is used on the Evos ( evo castings were not near as accurate as the twin cam era)

swap to one of these if the powder test shows that is the problem, your local indy will have one, Harley will not, they only carry the thin ones.

Mike

 

Good point except I can't find any oil running down the back of the inner primary. Also when I glued the gasket with shellac the leak slowed considerably. Also, the surfaces of the inner and outer primary covers, where they make contact with the gasket, look and feel smooth.

 

I would double check to make sure the leak isnt coming from behind the primary and dripping down, if you are positive it isnt then +1 for the aftermarket paper gasket, only thing that ever stopped my 1990 from leaking.

 

I had this issue and it was from the transmission main shaft. The oil would run down the back of the primary and drip off the primary drain plug.

 

I just had a similar problem fixed. The oil was leaking from the shifter arm which made it look like it was coming from the primary. This is a very common leak.

 

My 06 Road King had the same symptoms. Ended up being the inner primary seal. Was able to do it myself (replace all three seals) last winter. Good news is seals are cheap. If the dealership does it ouch.

 

+1 on shifter shaft seal.