Intake valve stem seals for Onan P216, P218 and P220 twin cylinder engines, replacing part number 509-0210 which is superseded to 509-0289. Two seals per order, which is a complete set for one engine. These engines fit a stem seal to the intake valve only, one per cylinder, and the exhaust valves are designed to run without one. Also fits the later replacement engines OL16, OL18, OL20, LX720, LX770 and LX790. Does not fit the Onan B43, B43M, B48 or B48M, or the P224, all of which use a different seal. Hardened valve seals cause blue smoke on startup and after extended idling. Inspect the valve guides at the same time, because a worn guide allows the valve to rock and will quickly destroy a new seal.
- FITS ONAN P216, P218 AND P220 TWIN CYLINDER ENGINES, and the later replacement engines OL16, OL18, OL20, LX720, LX770 and LX790. Replaces Onan 509-0210, superseded to 509-0289. Hardened valve seals are what put blue smoke out the exhaust on startup and after a long idle, and they cost nothing to replace next to the damage oil-fouled plugs and carbon do over time.
- TWO SEALS, ONE ENGINE. These engines use a stem seal on the intake valve only, one per cylinder, so two seals does a complete twin. The exhaust valves run without a stem seal by design. That is not an omission, it is how Onan built them.
- 509-0289 SUPERSEDES 509-0210. If your parts list or old invoice shows the -0210 number, this is the current part that replaces it. Both numbers describe the same seal.
- DOES NOT FIT THE B SERIES. The B43, B43M, B48 and B48M use a different intake valve seal, and so does the P224. Check the model tag before ordering. The P-series and B-series look alike on the bench and the seals are not interchangeable.
- WHILE THE HEADS ARE OFF. Seals are a symptom, not the whole story. Look at the valve guides, because a worn guide lets the valve rock and will chew up a new seal quickly. Check the seats for recession, replace the head gaskets, and set valve lash to your engine manual on reassembly.