Tacoma Tick -- but not? (solved I think)

Hey Folks,

I will try and get a recording of this soon and post for you. However, I wanted to throw this out there incase anybody has experiences similar.

I have always had the classic tacoma tick at idle. However, recently, I've noticed it gets louder while driving. It seems to be at its loudest about 2000-2500rpm, especially under load driving. However, if I am parked, and revving the engine in neutral to 2000rpm, I cannot reproduce the sound. It also seems to disappear above 3000rpm.

It's not a nocking noise, its just a tick tick that matches engine rpm. Everything seems to run smooth, no CEL/codes. It just seemed to develop over the past couple weeks. It's loud enough that you can hear it in the truck with the windows up. That never used to be the case for me.

I am tempted to try the seafoam treatment to see if it helps, but i'll run through this tank of gas first and see if maybe I just got a bad fill up.

Otherwise I can only think of a few things.

Injector noise?
Lifter/valve noise?
Manifold leak/crack?

PS. My Truck is a 2010 with ~200,000km on it.

 

First suspect would be an exhaust leak.
Is it louder when the engine is cold?

 

Good point, I forgot to mention that in my post. Doesn't seem to change as engine warms up. Cold/warm it's the same volume.

 

Noises are one of those things that are very difficult to diagnose remotely, they can even be hard to diagnose in person at times.

Manifold leaks typically seal up somewhat as the exhaust heats up, that doesn't mean you don't have an exhauat leak but it puts it lower in the list especially since you say you can't hear it at idle.

It could also be detonation, there was a TSB for some year model trucks to update the PCM calibration to correct it. It typically would occur on hot days pulling a slight grade at lower RPM.

I would think valvetrain noise would be evident at all RPMs.

I don't suspect injector noise as that's typically not an issue with port injected engines like the 4.0l.

 

Detonation could potentially be a factor. I wonder if a higher octane fuel may help.... should be a slower burn if I remember correctly? Might be a quick an easy way to test that theory.

 

Yea I forgot to mention to try running a higher octane fuel to rule out or confirm detonation.

 

Well, upon further digging:

1. I used higher octane fuel to r/o ping or detonation. Sound Still present.

2. I heard of a trick where you put some positive pressure in the tail pipe using a shopvac in reverse and use soapy water to look for leaks. As I suspected I found a leak in my manifold on the side I felt was the loudest. See attached video.

https://youtube.com/shorts/sRGOkxSWGO0?feature=share

Truck is going in for a frame replacement in a few months. I may use High Heat JB weld or similar to try and patch until then and ask if I buy they parts if they might be willing to replace both manifolds while the engine is out.

 

Bummer, but at least you found it.
Thanks for the update.