I recently had my camshaft and an oil leak supposedly fixed and new oxygen sensor. I then drove 250 miles and felt the car almost breaking down. Had to put it into a different garage. They have told me there's a hole in a valve and lack of compression in a cylinder. Is this something that should have been originally spotted by the first mechanic when their was symptoms of an oil leak which then persisted and after they fixed it had to fix it again adding a new oxygen sensor - should they have spotted that there was a hole in the valve and it was a cylinder problem?
My car has 61000 miles.
My car has a manual transmission.
It would really be difficult to determine what happened or should have been seen at what point. The only thing I can say with certainty is that if a valve had a "hole" in it, the vehicle would not have run 250 miles before running poorly. It would have been running poorly immediately. The engine would have been running on 3 cylinders the entire time. Also, a bad oxygen sensor would not be the cause of an oil leak. Oxygen sensors are placed in the exhaust system, one before the catalytic converter and one after. The engine control unit uses these sensors to read the amount of unburned air and fuel in the exhaust. Then the ecu uses other sensors like coolant and air temperature sensors to add or remove fuel from the air/fuel mixture. An oxygen sensor can be damaged by an oil leak but would not be the cause of an oil leak.
I wish I could give you a better answer but without physically seeing what was done and what happened, I can only guess.
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