Topic: Engine tapping?

[Wainiha]

Do all 4.0L motors sound like they're tapping?  It sounds like it is on my 2012.  I've heard other 4.0L doing it as well.  I have no loss of power when I stop it on an incline even at 80 MPH.

My 2000 3.4L never had this sound.  My 2012 Tacoma has 78,000 miles...

[Gnarly4X]

It wasn't making a tapping sound when it left the factory floor.

Something is not right.

Gnarls.

[05sport4x4]

Is it on the drivers side of the engine, near the outer edge of the plastic cover?  A mechanic told me it was a valve (I don't remember possible emission maybe VSV for EVAP) and is fairly normal to make that noise.  I'll see if I can take a picture of the area tomorrow.

[Gnarly4X]

Do all 4.0L motors sound like they're tapping?  It sounds like it is on my 2012.  I've heard other 4.0L doing it as well.  I have no loss of power when I stop it on an incline even at 80 MPH.

My 2000 3.4L never had this sound.  My 2012 Tacoma has 78,000 miles...

These automotive forums are notorious for describing sounds and then starting a discussion.  Then it goes into a long discussion of the noise, isolating or locating the source, then analyzing the cause.

If someone posts a comment or question about a “tapping” sound in an engine that has 78,000 miles on it and the owner is just now asking a question about the sound, my first thought is this sound is new. 

In this case, W.. may be asking a general question about the difference sound that this engine makes, and whether it is inherent in the type of engine, or particular to this engine.

A tapping sound in an engine to me means metal on metal and a singular sound, not balanced.  The rocker tick of a well-tuned and well-adjusted valve lash of 22 is balanced, meaning that all 8 rockers appear to make a very similar ticking sound in loudness.  The sound of a timing chain slapping against the timing cover is a distinct tapping sound.  The sound of my failing mechanical fuel pump made on my 1985 22R is a similar sound. The sound that my header or exhaust manifold makes when there is a gasket leak is a similar sound - not exactly the same, but similar enough that is causes me to think of several known causes that I have experienced.

In the 4.0L Toyota engine, like other direct injection engines, there can be a “tickiness”, similar to the sound that a diesel engine makes.

Describing sounds with words like tapping, ticking, clicking, squeaking, squealing, clunking, knocking all have some conceptual semantic or lexical variances to human cognition.  In other words, if I describe a sound from my engine as a tick, someone listening to the exact same sound might describe it as a tap.

Anyway…. That’s my pomp ‘n stink on the subject.

Gnarls.

[05sport4x4]

I agree it is difficult to describe noises on the internet.  I also did not notice a noise for a number of years.

In my experience which (I don't remember perfectly) I had heard a noise (tick/tap) when I was doing some maintenance years ago.  Later when I was having my smog check done I asked the mechanic (which I have used and trusted for many years) what it was.  I recall him disconnecting a device on the driver side near the engine cover and the sound stopped.  He said it was a normal sound from that device.  With the hood closed and engine running it was not very noticeable unless you were listening for it. 

By the way the 1GR-FE 4.0L engine is not direct injection. 

Background, this is a 2005 4Runner 4.0 purchased new, now with 220k miles.

Anyway that is my 

[Wainiha [OP]]

I need to do the old screwdriver to the ear and cylinder first I guess, and then everywhere else.  I agree with the clicking  or tapping sound treminology.  Hard to diagnose over the internet.

[Wainiha [OP]]

Screwdriver to ear on valve covers and headers all sounds are even and smooth.  I'm looking at the drive belt pulleys after I get home.  Timing chain/belt, I've never checked one. 

Would a motor out of time run like junk?  (Which mine does not)  Or could chain/belt be slapping from being loose?   Seems like at my mileage it wouldn't be likely. 

[Wainiha [OP]]

I found what looks like a vacuum hose that comes out underneath the engine cover.  It has a small black canister inline that then goes down beside the engine.   I can feel the hose pulsing when I put my fingers on it.

I called Toyota.  They don't sell the FSM as a book anymore.  It has to be downloaded.  I need it.

[05sport4x4]

I found what looks like a vacuum hose that comes out underneath the engine cover.  It has a small black canister inline that then goes down beside the engine.   I can feel the hose pulsing when I put my fingers on it.

I called Toyota.  They don't sell the FSM as a book anymore.  It has to be downloaded.  I need it.

Does this help?  The manual is for for a 2003 4Runner but mechanically the Tacoma and 4Runner are similar.

[Wainiha [OP]]

Yes.  Vacuum surge tank line is the one that is pulsing.  Is that normal? I have to get my engine cover off and see how of if I can diagnose the system.

Very top pis shows it exactly.  Thanks for the diagrams.

[Wainiha [OP]]

I guess the VSV solenoid opens and closes when it's energized.  That may account for the noise.  Next I'll figure on testing the solenoid.  I believe it runs on 12v.