Or so it may seem.

A few days ago, a clicking noise developed under the hood, at the time I was uncertain where it was coming from. Yesterday I changed my oil and filter, and upon starting the car again, the clicking noise sounded more like a rattling noise, the engine was idling very rough and any acceleration made it hesitate. In removing the oil fill cap, not only was the rattling heard better but one could feel "wind" blowing out of the oil fill hole (the engine idled even rougher when the oil fill cap was off). I installed new spark plugs but the problem wasn't reduced. This morning, the car idled even rougher, finally just breaking down. The engine could be started but then it stalls within 5 seconds.

I really don't think that the oil change had anything to do with this breakdown. It was probably just a coincidence, as there was some noise heard before the oil change indicating that something was wrong.

I read elsewhere that it could be the timing chain tensioner side guide. A Nissan Technical Service Bulletin (NTB 98055) on Nov 1988 on "Engine - Timing Chain Noise" for the 96's shows the abstract below. I read elsewhere the guides tend to break and ride around on the chain.

It is an Altima GXE with 131,000 miles. The amber "Check Engine" light was on for a few months, but a code analysis indicated that it was only a knock sensor and O2 sensor malfunction. I don't think that temporarily ignoring these sensor malfunctions for a few months contributed to the problem, but I could be wrong. The red "Check Oil" light never came on, which I assume means that the oil level wasn't low and there wasn't an oil pressure problem. I believe I have the DOHC KA24DE engine as opposed to the SOHC KA24E as shown with good photos here = http://jadcock.oldsgmail.com/nissan/valvetrain.html

Is the timing off here? Are things majorly messed up, like bent valves or something else? Again, the car starts but then stalls. Is this what the "blow by" coming out of the oil fill hole indicates, gasses blowing from the cylinders past damaged valves? If I just installed a tensioner side guide, could this solve the problem? What more might be necessary? Where does one get this tensioner side guide from? A general parts store, dealer, or other? I was wondering if it was worth trying to fix, if not much damage was done. Is it normal for air/gasses to blow-by through the oil fill hole?


from Nissan tech bulletin https://www.nissan-techinfo.com/nissan/TSB/Nissan_new/14431.asp
If a 1993-98 Altima exhibits excessive timing chain noise, the cause may be a broken tension-side timing chain guide on the lower timing chain. A new, metal-backed tension-side timing chain guide is available to resolve this incident. For any reason whenver this guide is replaced, use the new C/M parts listed on page 3. The new guide along with the two bolts that secure it must be installed as a set.