I've read a handful of threads on the subject and I am just wanting some clarification.

I recently got my 99 3.0 Mazda b3000 2wd road ready and notice some engine noise. It kind of sounds like a tapping noise. The noise sounds more like it's coming from the top end.


Usually it doesn't start until after a few seconds of the truck being on.


If I'm driving the truck and let off the gas the noise lessens, same as down hill.
I've ran about half a tank of 89 octane now and I can't tell if the noise is quieter or not. No real noticeable change.

Just wondering where I should start, 91 octane to see if it is ping, seafoam/other additive, valve adjustment, egr etc.

I'm probably going to see if I can get a decent recording of the sound at idle and under some load on my driveway.

 

try using zmax micro lube. it's a 2 part that goes in your oil as well as your gas. if it's an injector this will clean it or help it a bit and if you have a stuck lifter it'll help free it. could be an exhaust leak also

 

Tapping description wouldn't be octane related.

With engine idling, use a rubber hose on your ear and then place it around where you think noise is loudest, yes like a stethoscope.
See if you can localize it.

Yes, valve train or exhaust manifold leak are most likely sources
Fuel Injectors noise would most likely be described as a ticking noise.

If you can localize it then shut off engine, unhook one spark plug wire on closest cylinder.
Start engine, yes it will miss, but listen for tapping, if it is still there shut off engine hook spark plug wire back up and unhook next closest.

If tapping does go away with one spark plug unhooked then it is either an exhaust manifold leak or a Connecting Rod bearing starting to fail.

If tapping stays no matter what it is valve train issue

 

Good info Ron, I'll try those tomorrow if I get a chance and post back.