I was checking under the hood today as I'm preparing to replace the fuel filter. The engine is idling and a particular ticking noise caught my attention. It's probably been there all this time but I just never picked up on it til today. The ticking noise occurs in 1 second intervals. When I rev the engine up, the ticking goes away. It returns when the engine idles back. And its not the ticking or clicking you'd here from the valves. It seems to be coming from the rear towards the firewall. I thought at first it was knock sensor but I don't think the knock sensor makes any ticking noise. Perhaps this is just the EGR valve working, or some kind of solenoid or something. Does anyone have any idea what this could be? I'm pretty sure its not a knocking from the engine.

 

Valves, perfectly normal.......

 

does it tick with the engine off and key forward too.?

 

If it does, it is a relay, but I do not know which one....

 

You've got rats in there.

 

Idle Air Control Valve. It is behind the throttle body. You can hear it open and close (ticking). Only operational during idle, which explains why you only hear it ticking then. Completely normal.

Dave

 

 

Thanks for the reassurance guys!

 

its the brake booster lines.... nissan had two different designs of the hoses that came off the brake booster. If you have a long ? shape hose coming off the booster then thats the right one , if you have a little hose going to the other connector of the hose, that will cause a rattle/ticking noise at idle.