Perform a compression test on all cylinders, but it sounds like you have a bad valve (not closing completely). A compression test will tell you.
Bent valves will generally cause valve guide damage, were they replaced? It can also cause small cracks in the head.
As a general rule, if you lose a timing belt on an interference engine, you replace the head (if you are lucky) it can also cause piston/ring/cylinder wall damage.
Tuesday, December 30th, 2008 AT 6:40 AM