A loud ticking noise...

[poleclimber63]

In the last month I've noticed a loud ticking noise which became noticeable on positive throttle, above 3K RPM. As I havent been driving it much recently and I've been busy, I havent had much time to investigate. However, yesterday I had it out towing my utility trailer and after climbing a hill near my home, The tick got louder and subsequently, the ticking now becomes loud above 1.8K RPM. This afternoon I checked for some OBD2 codes--- nothing. It doesn't appear to have lost any power or throttle response---- and the ticking is loud enough that its not really possible to identify a location.

I have some ideas: collapsed valve lifter, timing belt/tensioner, or an engine control issue ie. a sensor or device controlled by the ECM.

I want to try some things before I start taking things apart...
I was thinking of doing a compression test and vaccuum test, maybe this will indicate whether I have a lifter problem. The timming belt was changed 60000km ago in a shop (I have records) so I'm not really thinking its that. Also, I have checked for codes, as I mentioned before so I'm not convinced it has to do with engine control...
If anyone has any comments or advice wrt to the next step, I'm open to any suggestions! Thanks, ahead of time!!!

 

[t4r4life]

these trucks tend to have loud injectors as they get older.

 

[98OzarksRunner]

Mine has a loud ticking at 2K underload, then again at 3K. It's been doing that for 20K miles, usually worse in the cold. Several threads about this, so it's pretty common. Guesses are loose heat shields (though mine don't appear to be), exhaust leaks (though mine doesn't). My guess is the guts of my cat are about to break loose (happened on my 95). It used to worry me but after 20K miles I just ignore it.

 

[slapdappy]

you can figure if it's engine or drivetrain. ask a friend to slowly increase rpm's while you look and listen under the hood.

 

[poleclimber63]

When I rotate the throttle....

I can hear the REALLY loud tick on throttle up, with the hood open. It sounds like its engine. Definitely not sheet metal/heat shield rattle.

 

[poleclimber63]

Oh Crap!!

I've consulted a local Toyota mechanic and he has given me a couple of ideas as to going about diagnosing my problem, however, after telling him what I'd done so far, he was of the opinion I had a broken valve spring. He was concerned that running it in this condition may bend a valve if I leave it much longer--- if I haven't done it already. He suggested I pull the wire to the coils one at a time --- I should notice a sharpe change in the noise when I find the correct cylinder....

 

[trdrun]

hey poleclimber63, did you ever figure out the source of your ticking noise? I also get a ticking noise somewhere between 2-3k rpm under load.

 

[poleclimber63]

Yup, Rod knock=con rod failure

hey poleclimber63, did you ever figure out the source of your ticking noise? I also get a ticking noise somewhere between 2-3k rpm under load.

Yup, Rod knock=con rod failure! I ended up doing a JDM engine swap!!

Link: http://www.toyota-4runner.org/3rd-gen-t4rs/167172-my-engine-swap-progress.html

Take a look at what I found in the oil pan: