I'd be very suspect of the oil filter side intake valve seat. Evidently it's been run hard without the gasket to seal the shroud and oil filter ( Gasket, Oil Filter Onan PN: 122-0502, Onan Parts Catalog, Page 47, Item 15) They will deteriorate over time, that's why I keep extras on hand. NOPE! I don't think so, I've been down that trail with my 4018 that the previous owner neglected. Fortunately I found a very good machine shop to repair the seat groove and install a new seat for me. I NEVER run my P218 without that gasket in place.