Not quite understanding automatic cam adjustment (2003 Pathfinder)?

Question

I have a 2003 Pathfinder. The mechanic discussed with me that there is some sort of hydraulic cam adjuster that is having trouble. I believe the cam basically rotates and has bumps on it that work a lever that open and closes the valves (affects timing of the opening and closing of valves). He said that this cam adjuster is hydraulically controlled by the oil in the car (use normal engine oil?). I also think he mentioned something about the cam adjuster controls the index, which I was interested in roughly how this works. It seems to affect the horsepower and perhaps the timing. Thanks for any insights and corrections in my understanding (autoshop was many years ago).

Answer 1

The timing chain in your car is operated by a hydraulic cylinder that relies on a good clean oil supply to maintain pressure. Oil serves two purposes: to lubricate, and to clean. If you have been using non-synthetic oil and go for prolonged periods without changing, the little oil galleries in your hydraulic tensioner may become clogged up and cuase your timing chain to loosen it's tension. The way to tell if you are having a lubrication problem is to remove your oil filler cap, and look inside the engine and on the back of your oil filler cap. If it is dark, mucky, or coated with goo or powdery brown, then the oil you've been using is probably gooing up the works!!! Make sure that your PCV system is in good working order, and have your engine de-sludged by someone that knows what they're doing. When the oil galleys and internal parts of your tensioner are clean, it should take up the slack in your timing chain. In general, whatever you see on the back of your oil filler cap is what the whole inside of your engine will look like. All engine oils do not have the same ability to keep things clean. Good Luck!!!