All, The boat is a 1989 17' Sunbird with the 4 cyl. inboard engine. All maintenance has been pretty well kept up. We went out on Wednesday and everything was fine. My buddy took the boat out On Sunday and came back with problems. We checked the oil before he left and it was fine. He got the the water, put the boat in and pulled out away from the pier about 200 yards. Turned on the bilge(sainity check) to make sure the plug was fine. Said it spit a tiny bit of white stuff out. Mind you that the boat had been running less than 5 minutes. He did not think anything of it. Drove the boat for about 2 hours before hitting the bilge again. This time there was alot of the white stuff. He brought the boat home. It seems that water had gotten into the engine and when he was running it the foam was coming out of the engine where on cars there would be a PCV valve. The first two things that come to mind are a cracked block/head or a blown head gasket. The reason I am having trouble with accepting these are that the boat had not been running long for so much water to get in the engine. I am not familer with how marine engines(cooling and hooking to the outdrive) work. Does anyone else have any idea's such as maybe a seal to check or something or do you know a easy way to narrow down just what the problem is. Thanks for the time and help.