Car & History:
- 99 Jetta, 2.0 AEG engine, manual. 86,000 miles. Bought at 70,000 miles 3 years ago.
- low oil warning once in 2013 maybe. since been using 5w-40 synthetic and used Ceratec additive once. Been doing regular oil changes.
- replaced original fuel filter at 80,000 mi
- gaskets have been going. Replaced thermostat and gasket. Replaced leaking oil cooler gasket. Valve cover gasket has been leaking for at least 1 year. Will replace.
- Replaced timing belt, tensioner, water pump, and serpentine belt at 84,000 miles.
- Flushed radiator at 84,000 miles.
- All break rotors and pads at 80,000 miles
- Replaced battery at 75,000 miles
- Gas mileage: 26mpg
- the sound is similar to a tapping. This has been going on for a year or more.
- very noticeable and loudest when cold
- worse in the lower gears
- diminishes once warmed up (5 minutes)
- happens only under load - so 5th gear and letting off the gas pedal (coasting) it’s not noticeable.
- JUST TODAY: 20 degrees F, and wouldn’t start on first try. Cranked for 6 seconds probably. Second time I turned the key, it started no problem.
Things of note:
- By peaking behind the engine, it looks as though the oxygen sensor wire covering (pre cat) is getting a little frayed at one spot.
- When I bought it I noticed new spark plug wires.
- Exhaust manifold gasket (to the head) is bad. So when it gets warm the bad gasket expands and stops the noise.
- It’s not the valve lifters because the noise goes away when warm and not really heard when gas pedal isn’t engaged.
- Replace the O2 sensor?
- 3 audio files. I put my car under my hood and went for a drive. You can hear when I engage the clutch, the ticking sort of goes away.
- Pictures of the frayed O2 sensor wire
Thank you for bearing through this and I appreciate all ideas!