I have a 2006 Volvo penta 3.0 GLP-E that has developed an oil leak where the PCV valve goes into the valve cover. Since the last trip I noticed where some oil leaked out and ran down the valve cover onto the block. The oil level on the dipstick looked low, before the level has always been at the full line. The motor has over 1600 hrs. It overheated back in the spring and I replaced a water pump and new head gasket, push rod cover gasket, exhaust manifold and riser gaskets. Changed oil and the boat has run fine since then, probably a total of 40 hrs in 5-6 trips with no oil leaking and oil level normal. When I shake the PCV valve it rattles like normal. I haven't popped the valve cover off to inspect oil drain holes, I did use gasket maker when I put the gaskets on. Any advice on where to focus my energy?