I have a toyota vitz 2002.I run my car on CNG. Recently my car has started vibrating in the morning or when the car is cold on CNG.I took it to the mechanic and he said that your engine head has tappets which are jamed so he made them free. Car was ok for a week only and again started vibrating.I start my car on petrol when cold and convert to cng while the car is running. Doing this my car work. My question is will this damage my valves or engine.
LPG or CNG is a very dry fuel and if not used with an upper cylinder lube you can hammer out vale seats, normally harder stellite valves and seats are used to lessen the effect, I would look at getting a drip system of upper cylinder lube fitted.