Rattle/Ticking (video inside)

[ForkliftDude]

Here is the basics. 98 Nissan Sentra GXE with the 1.6L GA16DE engine. Computer is throwing code P0110 (Intake air temp sensor) which I highly highly doubt is the problem but we are fully disclosing all problems. There is also an exhaust bracket that broke around the center of the car, a bit past the CAT. It rattles at odd RPMs, but it is a different kind of sound. Again, doubt its the problem, but we are disclosing everything. The car also doesnt seem to have a high idle on start up anymore. Well, it does when it is cold, but it only high idles for maybe 3 or 4 seconds before dropping to normal. There is no high idle at all on a hot start or a warm day (we have seen plenty of 90+ degree days this summer)

When I got the car there was not rattle/tick. About 2 months later I noticed a faint sound with windows up and no radio on. Now it has gotten louder and more noticeable. The sound increases with engine RPM, but not in proportion. No matter how fast you spin the engine, the rattle/tick only gets slightly faster. At high RPM, it almost goes away, but not totally. I noticed at times when the car is idling perfectly (think brand new car type idle) the sound is almost completely gone too... it seems like a vibration thing. The more vibrating, the louder the sound.

[youtube]http://www.youtube.com/watch?v=iIhE36rwOi4[/youtube]

What could that be? Ive heard a lot of things (an no one says the same thing) Its the valves, its the timing chain, its an exhaust leak, its a shield inside the valve cover, its this, its that

[MaximA32]

Can you feel any vibrations through the valve cover? It almost sounds like the oil isn't getting up into the top half of the motor to lubricate the valve train properly. It could also be timing chain guides. What happens is that they wear down and the timing chain starts to slap against the guides.

[ForkliftDude]

Can you feel any vibrations through the valve cover? It almost sounds like the oil isn't getting up into the top half of the motor to lubricate the valve train properly. It could also be timing chain guides. What happens is that they wear down and the timing chain starts to slap against the guides.

There is a fairly general vibration felt through just about every aspect of the car. After it gets nice and warm (20 minutes into a trip) it will either be idling dead still (almost showroom like idle) or it will vibrate enough to see it in the steering wheel and rear view mirror. No idle issues, RPMs are rock steady, just vibration.

I talked to a guy who thought it was the timing chain guides and he said he could fix it for around 200 but he wouldnt know for sure until he actually took apart a bit of the engine, which would be a charge to me regardless of if I had him keep going or not.

What could stop oil from reaching my head? I have no overheating issues at all and all my fluids are clean (so I am positive there is no head gasket issues)

[MaximA32]

Could just be a clogged oil passage. On your next oil change, run a bit of Seafoam through the oil to help break up any deposits that have built up. You can check out the directions and such on the can. Should be available at any parts store and even WalMart iirc.

[chickenflipu]

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