98 F-150, V8 4.6L, 112k miles

This has been a normal occurrence for the past few years. Every time I performed an oil change (10w40), I would hear a tapping noise from the passenger side of my engine. At times I would add an oil conditioner (STP Blue Bottle - really thick-type oil), and after a good 20 minute drive the noise would go away until the next oil change.

Well, the tapping noise is back. Very rapid tapping noise, speeds up as RPM's increase, does not go away as engine is driven. Odd...I'm not due for an oil change for the next 2k miles. At idle, it's like 4 taps/second. Very loud. It does it when the A/C is off, the noise drowns out or the tapping decreases as speed increases.

What can cause this? Any hinters/pointers/advice on what to look for. Please remember, I am not an Expert on engine rebuilding. Links are good. Pictures are nice.

Much appreciation. This website freaking rocks!

 

The timing chain on the motor that controls the opening and closing of the valves utilizes a guide/tensioner. I am not sure how many there are but they tend wear out over time and using the heavier than recommended oil is not helping the situation. As the guides wear you get a chattering sound that will occur and correspondingly increase in frequency as the RPMs increase. These are locates on the front of the block. They are expensive to replace because it requires a special tool and some serious labor. Hearing the noise on the passenger side may indicate it is the tensioner on that side of the motor.

 

There are two chain tensioners one for the right side chain and one for the left. While the engine is running and making the noise pull the injector wire off of each injector one at a time reconnecting the wire each time before removing the next. Start on the side where the noise seems the loudest. If it is a rod bearing then the noise should decrease about 50- 70 percent when the injector wire on that particular cyl is removed. The fact that it sounds like second order (double engine rpm) and comes and goes very well could be the tensioners. The chain tensioners,chains and guides should last a couple hundred thousand miles at least if the engine has been maintained properly. Sometimes sludge will build up and partially block the oil supply hole behind the tensioners starving them and generating a noise as the tensioner oscillates from loss of oil volumn and pressure. Good luck.

 

Awesome replies, guys. I know exactly what you're talking about now. I was afraid it may have been my valves tapping due to new/thinner oil or the oil not bonding to some parts. The hard question now is if anyone has had this repair done in the past, can anyone guesstimate how much damage it will do to my pocketbook? I doubt I can fix it myself. OR...can I add anything into my oil that would help the oil supply move around easier (like Marvel Mystery Oil, etc.)?

 

I dunno about oil additives but you could try one of the engine oil flush solvents. I don't know how much it would work or even if it is safe for the engine. Wonder what the reviews are about them on here.

 

The cam covers and front cover have to be removed to replace a tensioner and timing chain. It can get a little confusing when it comes to setting the timing on these engines and the valves can end up getting bent. Use a short piece of hose ( heater hose will work) as a stethescope and listen to various areas of the engine while it is making the noise, cam covers, front cover, etc. If it is a tensioner you should hear it real loud at the front cover about 4-5 inches down from the cam cover base. Likewise a valve train noise should be noticed under a cam cover. Also listen at the oil pan (rod bearing).You may want to remove the serpentine belt (only for a short time or you'll toast the engine)) and listen for the noise to go away. It may be a front end accessory such as A/C, p/s or belt pully or tensioner. Just some ideas here. With out hearing it it's hard for me to make an accurate call on this. Good luck.

 

Gotcha. I'll look into it a little further if I can. Appreciate all of the advice.