Hummer engine knocking?

Hi I have a 2003 Hummer H2 and it has 108,000 miles on it and when you start up the engine it starts a knocking sound. It comes and goes while the engine is running. What could it be and how to fix it. It has plenty of oil also. Thanks in advance.Hummer engine knocking?It could be one of many possible things:



1. The valves in your engine need to be adjusted: Adjust valves or replace hydraulic lifters as required.



2. There is a lot of sludge in your engine that is stopping oil from circulating properly: Flush engine and replace oil and oil filter.



3. The engine's valve lifters are collapsed: Replace valve lifters.



4. One or more of the engine's valves are stuck: Remove valves and repair or replace valve guides and/or valves as required.



If you know how to check for these things on your own then do it if not, take it to a mechanic.



Good Luck.Hummer engine knocking?add a heavyier weight oil like 20/w50,, and sell it fast as possibleHummer engine knocking?Engine knocks usually (but not always) indicate a bearing is failing. If so you're in for a major overhaul, perhaps $3,000.