yesterday afternoon i got in my car to go to a friend's place and when i started the car i heard a loud, constant clicking noise coming from the engine bay. i got out to listen and it sounded like it was coming from the back side of the block.

i turned the car off and strarted it up again. it seemed to struggle slightly when i started it and the clicking noise was still there. my idle was at about 1200 and when i tried to back the car up a little the clicking noise got faster as RPMs got faster.

i shut it off and started it a couple more times and on the last time the sound didnt come back. everything seems to be fine since then. idle is back to normal at about 700 RPMs.

any suggestestions on what it may have been?

 

Dirty IACV. Check the write up in the 4th gen section. It is located in a sticky at the top labled How To.

 

you're sure that's what it is?

im under warranty so ill most likely try to have the dealer do it.

 

If it isn't the IACV, it could also be a lack of oil in the valvetrain. If the car sits too long, oil drains down from the heads. This causes the valvetrain and such to start tapping loudly at startup until oil pressure is high enough to supply the heads. Check to see if you have the O.E.M (Nissan) oil filter, Bosch is good too. They both have anti-drainback designs, but that doesn't mean it won't happen. Don't think anything like "but it's a brand new car!" it doesn't matter. If the car sits for awhile, it happens, cuz oil is fluid and fluid drains. It's just doin' what it's supposed to do.

note: Low oil pressure and temp is the reason for a 1200-1500 RPM idle at startup, to get oil flowing. That's why you're supposed to let the car warm up some, and why the IACV uses fast-idle at startup. I always at least wait for the idle to drop to ~1000 RPM or just drive between 1500 and 2500 RPM for the first ten minutes or so. It could very easily be either one.

 

The IACV is located at the backside of the block where you said the noise is coming from. A dirty IACV or stuck IACV has been known to cause complicated start ups.

It does seem odd that it would be dirty since your driving such a new car but from the symptoms that's what it sounds like to me. Either way it is under warranty so you should be fine. When did you get the car, how many miles? Was it from a dealer?

If the clicking only lasts for a few seconds then I would go with Badaxx's answer. If you are using a thin oil like 5w-30, and let the car sit for a while you could get clicking from the valves until pressure builds up, this should only last a couple of seconds at the most though.

 

i got the car new back in february of last year.
the clicking lasted for about 4 or 5 minutes.
and yes i am using 5W-30 and i believe the car may have been sitting for about 24 hours before this happened.

 

4 or 5 minutes is definitely not oil pressure. Reeper's right, it should only last 3-6 seconds on a warm day, but never more than 8 or 9.
Take that thing in to the dealer (stealer) and get that thing out. Tell 'em to get a new thing and to put the new thing where the old thing was. Then the whole thing should be good to go!










I do not in any way, attribute this to Yogi Berra, this, well, that, was, um, is, uhh mine.

 

mine does this too but not on startup. It in fact does it way after the car is warm, And been running. I think its the IACV and have cleaned it. But the noise persists. WTF could it be?> Could i just need a new one?

 

That's the power brake check valve. There was a TSB back in 1998 regarding the noise. When I first heard it, my car had less than 10k on it so I freaked out. The dealer performed the TSB and it was no different. I'm not sure if I can find the paperwork it will probably show the part #.....

dang I have all my paperwork and I found 4 occasions where I complained about the ticking sound. EAch dealer response was can not duplicate customer concerns etc. BUT I remember on the old forum someone scanned the TSB and it was called power brake check valve. Don't worry about it, I've driven my car for 5 1/2 years with the tick. If you really listen carefully, as your rpms go up, the sound goes away. When your motor goes back to idle, the tick slowly comes back.

 

car is a 2002. but i noticed that when i gave the car gas and the RPMs got higher, the clicking noise was just as loud but it begin clicking faster. it sounded like whatever was making the noise was in some way connected to a belt or something else that turns with the crank.