Oil Cap

[Barnabyp]

I'm probably being naive, but this morning when doing my rad water level check i decided to check the oil filler cap for any signs of discolouration. The engine was running and i removed the cap, to my surprise there were exhaust fumes blowing out. Is that correct? I didn't think it was a direct link with the engine.
Please put my mind at rest.

[Morr]

I'm probably being naive, but this morning when doing my rad water level check i decided to check the oil filler cap for any signs of discolouration. The engine was running and i removed the cap, to my surprise there were exhaust fumes blowing out. Is that correct? I didn't think it was a direct link with the engine.
Please put my mind at rest.

Getting fumes from the oil cap is not normal. Check if you also have fumes coming from dipstick tube. Fumes from oil cap can indicate worn/burnt valves/valve guides. Fumes from dipstick tube can indicate worn piston rings. It you have such fumes the first thing is to check and clean the breather system to see if it helps before going any further.

[stara]

don't confuse 'exhaust gasses' with normal crankcase pressure, as there will always be a small amount of pressure as an engine is not 100% airtight during combustion. a telltale sign of worn rings/ valveguides/seals is blue smoke from the exhaust. worn valve stem seals will show blue smoke on startup, worn rings will show blue smoke on general driving.