I started the car last night to take the wife for dinner and it started making a knocking sound from the engine. The knock did not change in frequency when the rpms changed. There was a little oil in the air breather tube and on the block behind where the air breather tube attaches to the engine and an oily black soot on the back bumper above the left exhaust pipe. The car has the Mina exhaust so both sides are separate. I couldn't see any oil on the driveway or anywhere else on the engine. The car gave me no codes or warning lights. The car was going to the mechanic on Wednesday to get it ready for winter storage so he's going to fix what ever is wrong but I was wondering if you folks could give me the heads up on what to expect. I'm not mechanically inclined so I'm pretty clueless. Thanks in advance for any insight.

 

I can't think of any engine related sound that does not change with revs.

 

Can you make a sound recording and post it?

 

RJ237 - the car didn't run for very long, less than 2 minutes. I started the car, got out, heard the knocking, went into "oh sh*t" mode and shut it off. When I first started the car it reved up to 1200 rpm and went down to 600 rpm as normal but I didn't notice any change in the frequency of the knock so this could be a false diagnosis. I didn't rev the engine or anything.

Michaelh - to be honest I don't want to start the car for fear of doing more damage. What ever it is it's over my head to repair anyway. I thought someone might have some ideas. I was hoping to avoid the heart attack factor when I get the news from the mechanic. What ever it is the car will get fixed.

 

Sorry - that was a dumb suggestion for an engine knock, although I can't think of a non-rpm-related one either.

Fingers crossed it's something trivial.

 

There is a difference between a knock and a tap. Knock usually from low down and a tap from the valve gear.
Let us know what you find as I have a tap on occasions.