notherjones

Driving home last week I started hearing a soft tapping from under the hood of my 94 4x4 (3VZE + auto). I was close to home and kept going, and by the time I got there the noise was significantly louder. Not like an engine about to sieze, but very easily heard over the other noises under the hood. The obvious thought is something serious in the heads or block. I parked it and haven't driven it since. Oil level was fine and the oil was recently changed. No coolant in the oil or oil in the coolant, near as I could tell.

I started it last night and used a stethoscope to try to isolate the source and was surprised by two things. First, it was barely there until the engine warmed up a bit, and second, I heard little from the heads or block. The noise was very loud when I touched the probe to the right fuel rail or the front fuel connector line. The sound is sort of like normal injector ticking, but lower in pitch and *really* loud compared to what I'm used to.

Does anyone know of an injector failure that would make the thing hammer? I emphasize that this came out of the blue within about 3 miles of driving at maybe 40 miles per hour.

keithguts

Well it sounds to me that you might have a bad injector. They do tap like a bad valve as I went through this as well. I would try some injector cleaner, of the sea foam treatment to see if this will help.