I have a 2007 Sentra 2.0S that I bought new in Nov 2007. Motor makes ticking / knocking noise when it cold and only have 35,000 miles on it yet.

Knocking is most certainly not plugs and wires. A lifter could be it or you could have a broken piston rod/end. Not good and should be looked at by a mechanic.

Your hearing lifter noise common in most cars in cold weather I have a 2001 sc1 same engine as yours here's how to get rid of that ticking sound go buy a quart of Lucas synthetic motor treatment change your oil and leave it 1 quart low add the Lucas synthetic oil stabilizer within 1 week you will not hear the noise agian reason your hearing the noise is there's no oil at the top of the engine on a cold start oil when cold is thicker hints why your noise in your engine what Lucas does is eliminate the dry start by the way my engine has 288,000 and does not use a drop of oil after you use this product you should use it every oil change you will see your car will thank you regards Chris

The ticking may be coming from the valves, and or, the rocker arms, and or, the lifters. I have a 1996 Chevy Cavalier that has valve train noise and has 230,000 miles on it and is still going. If you are taking the oil cap off when the engine is running, you will see oil spitting out of it, since the engine is lubing the top end. Most vehicles have a pressure gauge on the instrument panel, and or, an oil light, which would show pressure problems. Try to isolate where the ticking is coming from by using a mechanics stethoscope, or a screw driver to your ear. The handle part of the screw driver goes to your ear of course. Place the scope or screw driver blade close to where the tick is coming from and you will hear the ticking get louder the closer you get to it.

Have your valve lash adjusted. Overhead cams need the lash done every 25-30K otherwise after some time they make a loud ticking sound. If the motor makes a "Knocking" sound, it may be a lower end noise, and there is no adjustment for that.

If your engine has a rod knock the engine has to be rebuilt or replaced rebuilt is about $2000 to $3000 dollars and a new motor even more.It is unusal for a rod to be out around 60,000 miles unless it was ran real hard or run out of oil or way low on oil.

Sounds like you are describing lifter noise. Go to the car store and buy a pint of Berrymen's Chemtool. Next time the engine is cold, pour the Chemtool into the engine oil. Do your normal driving for the next few days or weeks until you have 150-200 miles (none of them should be highway miles) on the engine, then have the oil changed. Drive for 2000-3000 miles, and do the same thing all over again. Repeat this a couple of times. If the lifter loosens up, your good to go. If it doesn't, then it will have to be repaired by tearing into the engine.

It is probably your lifters sticking. Check your engine oil level and if thats fine, then add some oil detergent/additive that says it will "reduce engine knock and free sticky lifters" run with that additive for a couple hundred miles or until the noise gets better. then replce your oil after that without using the additive

the exhaust was always good for making noises under hard driving as it expands with heat than contracts under cooling but like carlo says more info required

Is there any smoke when you first start it? what is happening is the valve seals are probably worn and letting the oil seep past them. when your engine is first started it has no oil or very little oil at the top of the engine, thus causing the knocking noise. could be more but this is a most likely answer. oh and is you haven't changed your oil every 3,000 miles you had beeter start doing it.... answer knocking sounds usually come from bottom of engine try a better quality and correct viscosity oil

It is part of the waste gate just above the gas tank. It periodically checks for leaks and pressurizes and releases. Gives a ticking noise when it does this. Not a problem and GM is aware of this and said its normal on our cars.