have an Lreg discovery, started hearing "tutting/popping" noise from top of engine, removing filler cap produces exhaust fumes. had 1 guy tell me valves are gone, another says head gasket. can anyone throw a little light on the subject,,, any help greatly appreciated.
thank you

mdfnick, May 2009

Measuring the compression will be helpful. If all cylinders are not the same, then there's a problem. Two adjacent cylinders low is usually a heat gasket, one low could be valve/s

trover, October 2009

There will always be a certain amount of fumes chuffing out of the oil filler cap when its removed - this is largely dependant on engine condition. If the head gasket has gone, there will be oil emulsion in the radiator fill bottle, maybe water in the sump, together with expulsion of coolant, more than likely. If there is valve failure, the engine will be misfiring. You may well need a second opinion here, but check that the exhaust manifold gasket isn't blowing.

John, May 2009