I have a 99 Taco Prerunner w/V6 and 103000 miles. About 2k ago I noticed a tapping sound when the truck warmed up and the idle lowered - Tapping goes away upon acceleration 900+ RPM, but at Idle it taps rather loud most of the time. I switched from 10W-40 to 5W-30 to try and solve the problem - no success.

Any thoughts? Seems to come from the drivers side.

Thanks
Tim

 

Actually, my experience has been that thicker oil reduces tapping, but that was with conventional rocker arm/tappet valvetrains. On these you have to deal with shims to adjust the valves, so I am not sure how much thicker oil would effect things.

Do you track your MPG? If so have you noticed a gradual decrease or anything abnormal that could be associated?

I am guessing it is "just" a noisy valve.

 

Thanks for the reply - MPG has remained steady @ 18isg MPG, however, I do have an O2 sensor that needs to be replaced.

 

Do you know what an exhaust/intake leak sounds like? Sometimes those "dissappear" after the engine heats up because the gasket expands. I would lean more towards exhaust in this case, if anything. Only problem is that the exhaust gasket at the head is layered copper; very rarely do these ever go out. Have you examined the exhaust piping?

Another idea is to get a stethoscope and listen to the engine more intently to narrow down the exact location of the sound.

 

My first thought was a exhaust leak, but it does not start till the engine has warmed up. I also thought about a loose shield.

 

With the engine off and cool, lightly tap around under the truck (where you suspect the noise to be) with a rubber mallet, including the exhaust piping. Listen for rattles, etc.

Is this a timed sound that you hear, or is it sporadic?

 

I have a '98 Taco V6 with 109,000 miles. It makes the same noise. I did have the valves adjusted about a year ago, but that did not get rid of the noise. I have not ruled out an exhaust leak, but I don't think that is it either since, as with yours, it does not occur until the engine is warm. My feeling (and that of my mechanic) is that it is something deeper in the valvetrain, and thus harder to fix, but he told me it was not serious.

Also, these engines do have a reputation for being rather noisy.

 

Nope. It's [probably] not the valves or and exhaust leak, or anything like that.

It's the "Annoying Ticking Device".
It's a little black box on your drivers side of the engine compartment. Has some hoses running into it.
Listen closely.

 

Yes, the charcoal/evap canister makes a timed "hissing" sound, but I was under the assumption that he could distinguish between a valve tap and a "hiss." I know I can tell the difference.

 

Nope, not a hissing - "Annoying Ticking" would be a real close description though - I will check it out

 

Well, maybe it's the sign of a worn out evap canister or something, cause I know mine ticks . . . . only at idle though. It's very annoying, but I can live w/ it....until I find out if it'll hurt anything to rip it out and crush it.

 

mabey its a pilot or throw out bearing,

thats the noise my 86 is making right now, sounds like a ticking, goes away at about 900 or so rpms.

just a thought.

wade

 

my engine makes a slight tap, that only I can hear...or someone with a trained ear....I dont let it bother me. At first I thought it was the valves or something, but when I listen closely it almost sounds like a belt tensioner taping with rotations....I dunno though, I'm not gonna worry about it since I've heard other Tacos in parking lots with the same sound.....