Ticking engine noise (diesel?) when accel from 60 to 80 km/h

[gta_driver]

I am having a bizarre engine noise. It's ticking, almost like a hole in the exhaust manifold or a bad bearing, and only happens when accelerating in 4th gear from 60 to 80 or 90 km/h, under moderate to severe load.

It's a 2005 Mazda 3 GT (2.3L, manual 5-speed) with 60,500 kms. Bought the car in November, and since then replaced alternator and #3 coil and spark plug.

Right now it's running strong and great, but does have this weird noise. I heard the noise on Friday and I can reproduce it every time.

Interesting point: Westowne mazda performed oil change 2 weeks ago, and they put way too much oil. It goes about 1 cm above the MAX line on the dipstick. Could be too much oil creates too much pressure and messing with the valves?

Or is this the beginning of the infamous "sounds-like-diesel" clatter that I keep reading about?

Thanks!

[gta_driver]

Fixed.

Turns out it was the rubber mount for the Fujita intake. It broke in two, almost sliced in half. Very strange, it has been on the car for only 4 months and less than 5000 kms.

POS engineering.

[Blue_Jinnee]

good :)

[gta_driver]

false alarm!

not fixed... the noise is still there :(

Does 2.3L have VCTS? If so, I can try unplugging the sensor to see what happens without it.

[gta_driver]

Disconnected both sensors to VCTS, no difference noted. Interestingly enough, no CEL either.

Anyway, the more I listen to the noise, the more it sounds like an exhaust leak in the manifold, although it's not exactly the same noise.

Since the car runs fine, I will see what happens with time. Sigh...

[sas]

Hard to diagnose thru internet.
From my experience 80 percents of sounds are coming from exhaust. The last time I was certain in engine noise and again it was the shield of catalytic converter. Sound was just reflecting from ground.

[gta_driver]

I think you're right, sas, that it's exhaust. My CEL eventually came on, then I connected VCTS back, and the light still stayed on until it eventually cleared on its own after several small trips.

Anyway, the more I drive the more I'm convinced the sound is from a leaky exhaust.

What's interesting, I was thinking the other day, nearly all 4-cylinder cars sound like they have a leaky exhaust manifold. I don't know whether that's due to the thin materials used in the construction of the manifold/exhaust system or due to the firing order of only 4 cylinders, though i'm nearly 100 % positive it's strictly exhaust.

I don't hear V6 or V8 engines make the same sounds, especially not V8s. Is there such a difference in exhausts for the two engine types?

I keep thinking that all 4-cylinder econoboxes use thinner materials precisely because they're econoboxes.

Some exceptions are the quieter exhausts of 4-cylinder Mercedes or Audi, although Audi has a turbo which might quiet the exhaust somewhat.

Anyhow, just an observation I made several years ago.

[sas]

You have this sound under loads, when the exhaust pressure is maximal and the engine moving on the engine mounts. I think the most expectable things are: something hitting or crack in exhaust. Every time these causes are different.
As for materials, yeah, to compare with my 323 , the manifold is from stainless steel now, but so thin that I don’t know what is the better.