Hi All,
I’m hoping you can help me with an oil leak problem on a K Model I recently got from my brother. My experience with Harleys has been on a 1954 Panhead I have owned since 1969. The K engine was built up by my brother from a mix of parts. From my brother’s notes and my inspection, it has left side 53 K case (belly number 553-1219), right side case is a KR (belly number 223), with KH flywheels, pistons, cylinders, and heads. I have only recently gotten it running, and it has a steady oil leak from the small vent hole in the center of the primary filler cap. There is no oil leaking from the timing case breather tube. As best I can tell, it has no breather valve between the crankcase and the primary case. From searches on this forum, a 53 K should have 25100-53A Crankcase Oil Syphon Tube Assembly. This K has what appears to be the 58-69 XL/XLH primary chain tensioner. Where the lower hole should have the syphon tube assembly, this K has a solid bolt.
I initially thought that without a crankcase to primary case vent, there would be no path from the crankcase to the primary case to pressurize the primary volume, but then I thought there might be a path past the flywheel sprocket shaft and into the primary case. I don’t know what flywheel sprocket shaft and seal system is on this K motor. If crankcase pressure is getting past the flywheel sprocket shaft and into the primary case, with no crankcase to primary vent, there would be no way to relieve this pressure except out the primary filler cap vent hole.
If this is a plausible theory for my oil leak, do you experts have any suggestions for adding a crankcase to primary case vent in this motor? I have found the 25350-37 breather valve on eBay, but haven’t found the 25111-53 crankcase oil syphon tube screw or the 25101-53A crankcase oil syphon tube. Since I don’t appear to have any crankcase wet sumping, would it be a reasonable solution to machine a screw that would accept the breather valve and forgo the syphon tube? Another alternative I have considered is plugging the primary filler cap hole, drilling thru the tool box mounting hole on top of the primary case, and adding a vent fitting and hose.
Any suggestions you experts might have would be appreciated.
Thanks, Dennis