Renault opel camper van

The van has knocking in the engine . But it going with no problem other than the knock .we we in kerry last week and all over in it i have tested it twice. With out any problems. The van is tested to 2 .27 .tax is up at the end of aug. The van camper is too and a half years old with 4 beds out side shower and gas + power out let .up front it's got double reverse seats..satellite. Ac cruise control. In the back composting toilet.diseal heater..too agm. Leisure battery. 450 solar..epever mppt soler control. Fridge freezer. Too ring cooker with oven. Loads more ..ring and I can tell you all about it . And I have the extra high roof .if needed. Loads more . Easy taxed