Hey guys, I normally hang out in the 80-86 F100-F150 section however I have a 98 Ranger 2.5L 5 speed as my DD. It has 165K on it and within the last 6K it has started to get a bit of a ticking noise. The only time I get this noise is when the motor is under load, I don't hear any of it when I'm idling or revving the motor. I've got a buddy of mine that is a mechanic and he listened to it and he and I both agree it's we don't think its a valve train issue. I was wondering if you guys have any insight on this at all? Thanks

 

Your description as "a bit of a ticking" would first lead me to take a close look at the exhaust. A tiny leak where the manifold mates to the head would be impossible to hear until a load was placed on the engine. Try listining with a stethoscope around the manifold flanges. With the scope, you will probably be able to hear something even at idle.

 

I will give that a shot and see what I come up with, we were both thinking it might be an exhaust leak possibly. Thanks

 

Under load engine noise could be spark knock & with the mileage you have on this puppy a lot of things belong on your suspect list.

If your exhaust stethoscope inspection doesn't bring joy, look to bringing your ride up to date on All past & present due scheduled maintenance items, like using the Specified heat range & design type plugs, wires, O2 sensors & filters. Make sure the PCV valve has been replaced, as if it's sticking open, or its rubber connecting hose is dryrotted & leaking, it can cause a lean mixture & spark knock.
If the engine temp is on the high side, suspect a sticking thermostat, or clogged cooling system, as that can cause under load detonation.

Make sure you don't have any other vacuum leaks, the MAF sensor is clean & your up stream O2 sensors switching speed is up to snuff, of if they have over 75-100K on them, their switcing speed likely belongs on your suspect list, as it'll get slow with age & mess with fuel trim causing it to be on the lean side & can cause under load spark knock.

With the mileage you have, carbon deposits should also be on your suspect list & can cause under load spark knock mischief. So you could try a tank of higher octane fuel to see if things get better & if so, suspect combustion chamber carbon deposit buildup.

So if carbon deposits are high up on your suspect list, consider trying a 20oz bottle of Techron Concentrate Plus in the tank at the pump before fill up, so you get good mixing & using Chevron, Texaco, CalTex gas, which have Techron in them, or Shell gas which now has PEA in it, will raise the treat rate 10X above that of the pump gas alone & will usually tidy up the fuel injectors, intake valves, piston crowns & combustion chamber of deposits in one treated tank.

Do some spirited driving durning the treated tank, with daily rpm above 3600 for 2-3 miles as Ford calls for in their 4.0L decarb proceedure & run most of the treated tank out before refilling.
Then regular use of a Top Tier fuel will usually keep things clean.

More thoughts for consideration, let us know how your trouble shoot goes.