How to Fix a Primary Oil Leak on a Harleyby Kyle McBride
Harley-Davidson motorcycles use a chain-driven primary system to transmit power from the engine sprocket to the clutch housing. Drive plates in the clutch pack engage the plates in the clutch pack to drive the primary shaft in the transmission. The primary chain case cover contains Harley primary chain case lubricant which lubricates the clutch pack and primary chain. Failure of the primary chain case cover gasket or either of the two inspection cover gaskets will result in a leak and need to be replaced.
Draining the Chain Case
Start the motorcycle and drive it until it is up to operating temperature. Park the bike on level ground. Remove the battery's negative cable bolt with a 10 mm wrench. Pull the battery's negative cable off of the battery post.
Place a catch pan under the primary chain case drain plug. Remove the five clutch inspection cover retaining screws with a ratchet and Allen driver and pull the cover off of the primary case.
Remove the primary chain case drain plug. Allow the lubricant to drain fully from the chain case. Remove any debris or metal salt from the drain plug magnet. Inspect the drain plug O-ring for signs of wear or damage and replace if necessary.
Install the drain plug. Torque the drain plug to 14 to 21 foot-pounds with a 3/8-inch torque wrench and socket.
Removing the Cover
Remove the rider and passenger floorboard mounting bolts from the frame with a ratchet and Allen driver. Pull the floorboards off of the vehicle.
Remove the jiffy stand bolts with a ratchet and socket. Remove the jiffy stand. Loosen and remove the shift lever screw with a ratchet and Allen driver. Slide the shift lever and rubber spacer off of the shifter shaft.
Remove all of the primary chain case cover bolts with a ratchet and Allen driver. Pull out on the cover to separate it from the inner chain case.
Scrape the old gasket material off of the gasket surfaces with a gasket scraper. Wipe the inside of the cover clean with a shop rag.
Lift the primary cover and the new gasket into position. Loosely install all of the cover bolts. Torque the cover bolts to 108 to 120 inch-pounds with a 1/4-inch torque wrench and Allen driver using a star pattern.
Install the shift lever and lever screw. Torque the lever screw to 18 to 22 foot-pounds with a 3/8-inch torque wrench. Install the floorboards and floorboard mounting bolts. Torque the bolts to 30 to 35 foot-pounds with a 3/8-inch torque wrench and Allen driver. Install the jiffy stand and jiffy stand mounting bolts. Torque the bolts to 15 to 20 foot-pounds with a 3/8-inch torque wrench and Allen driver.
Add 38 fluid ounces of Harley primary chain case lubricant to the primary through the clutch inspection hole. Install a new clutch inspection cover O-ring onto the cover and position the cover over its hole. Torque the inspection cover bolts to 108 inch-pounds with a 1/4-inch torque wrench and Allen driver using a star pattern.
Install the battery's negative cable onto the battery negative post. Install the battery bolt and tighten it securely with a 10 mm wrench. Start the vehicle and check for leaks around the primary and clutch covers.
- The torque specifications given are for a late-model FLT. Check the torque specs for your year and model bike.
Things You'll Need
- 10 mm wrench
- Allen driver set
- Catch pan
- Wrench set
- Gasket scraper
- Shop rag
- New primary gasket
- 1/4-inch torque wrench
- 3/8-inch torque wrench
- Harley-Davidson primary chain case lubricant, 38 fluid ounces