2003 Jdm GT 2.0 Spec B Mechanical Ticking only when fully warm

[4mythica]

I am having some issue with my engine ticking/knocking when warm and am looking to see if anyone know what the issue could be. I drive a 2003 JDM Legacy GT spec.b with the EJ20Y engine. I dont know much of the history of the car as its a recent import from Japan, but oil (5w30) has been changed in the last 2 months. This noise has existed ever since i have started driving it about a month ago.

It is not making the noise when cold or warming up. It only begins to make the noise when its fully warm ( i.e >80°C), and only if it warms by driving, not if it warms up just by idling. The noise seems to match the rhythm and speed of the injectors. It audible at idle, getting louder/quicker upon acceleration to about 2k-2.5k rpm, then it either stops or the engine noise drowns it out. It hard to exactly hear where its coming from, but it seems to come from the back of the engine. Maybe over towards the right (Cylinder 4) but its hard to quite pin point it. I can also hear it while driving, but only if i am next to a curb for the noise to re bound off of, not if i am in the middle lane and away from the curb. 

The car has some aftermarket gauges, and typical warm oil pressure is ~20psi at idle, and around ~45 psi at 3000 rpm. After driving for 1/2 hour oil temp never goes much above 87°C. I have also religiously checked the oil after each time i drive it, and the levels are fine, and i havent seen any flecks of metal in the oil yet. I also havent noticed any power loss, and the car runs pretty smoothly. The ticking noise doesnt cause the engine to jump around or anything. I could probably have a coin standing up on the engine and it wouldnt fall over when it excelerates. 

Its more of a ticking noise than a rattling or knocking noise ive heard from rod knock before. Could this be from the Valve train maybe? I have also smelt a little exhaust in the cabin when its colder, though it goes away when its warm, but could it potentially be an exhaust leak?

Any help would be appreciated and if needed, I can try and get a video with the noise.

Edited October 1, 2022 by 4mythica

[KZJonny]

I’ve had this happen on my motorcycle. The culprut was an exhaust leak where one of the pipes meets the head.

I had reverse symptoms in that is was bad at idle, but went away after warming up. It definitely was a ‘ticking’ noise, and kept time with engine rpm for obvios reasons.

Might not be your problem, but it’s at least a reasonably easy thing to rule out. If you’ve got some ramps, or a tall curb you can drive two wheels up on, you’d probably be able to figure out where it is.

For the few dollars, a mechanics stethescope is pretty handy to help track down noises lie this.

https://www.amazon.ca/Lisle-52750-Stethoscope-Kit/dp/B0015DLMOO/ref=asc_df_B0015DLMOO/?tag=googlemobshop-20&linkCode=df0&hvadid=293006272454&hvpos=&hvnetw=g&hvrand=13570374708858711911&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9000774&hvtargid=pla-569409355664&psc=1