pbuenafama, you are going to have to physically check clunk and tank for leaks, once satisfied everything is ok, tune engine like you normally do, then richen engine 2 clicks. You should be able to tell pretty fast if engine is going to stay running. If not land and richen 2 more clicks or untill engine stays running. If you don't have a tach, get one and this will help you determine how your engine is running. Top of high pitch whine is not always best tuning point.