i35 Engine Trouble - Loud Tapping/Knocking

[DK SPL Audio]

Hi guys, this is on my gf's 02 i35 with 201,000 miles.

Went to start it this weekend and at idle had a loud ticking/tapping/knocking. It is not a equally timed sound but happens often (2-3 times a second maybe). I have done a lot of reading this weekend and found when the timing chain tensioner goes the chain can slap against the cover, it sounds similar to the youtube videos that show that. I left the car sitting because I was busy until today.

Now, I checked the oil today and it was low, just at the bottom of the dip stick! I poured in almost about ~3/4 of a qt and the car wouldn't start. I went to the store and got another qt and poured in another ~3/4. I tried starting the car and cranked for a long time (15 seconds or so) and then finally started but the clicking is still there and the gas pedal was unresponsive. I did not even take the care out of park, it was running rough.

Any ideas here? My gf said the last time she drove it she did not notice anything but who knows, she doesn't pay attention to vehicle issues. I know the 3.5's eat oil so I often checked it and topped it off but this time it was low, I believe I just put a qt in about 1.5 months ago. I always used Amsoil 5W-30, perhaps too thin for a engine that is known to burn oil and with this many miles.

[NutriaforBreakfast]

Oil at bottom of dipstick is not too bad-the oil viscosity you are using seems ok too.

Based on my experience when you start the car up and you hear a timing chain, the noise
MIGHT go away after it warms up (usually the tensioner pressures up enough for the
tensioner piston and spring to push against the slack arm guide) OR if the chain is really loose
it will continue to make noise hot or cold.

Generally speaking a bad valve, lifter, or other deeper engine component will make a noise hot or cold

[DK SPL Audio]

Thanks for the reply. So you are recommending I let it warm up a bit and see what happens? Weird part was it was running fine the last time we drove it. The next time I started it there was a loud clicking (imagine a big screwdriver hitting a thick aluminum cover type of sound). I don't understand this happening unless the tensioner gave out completely all of a sudden.

I have read about newer 3.5's having the chain guard break and slide down which allows the plunger on the tensioner to extend fully. However, this does not seem like an issue on 02 3.5's.

Not even really sure where to start here...

[ThePirate]

I recently took possession of my dad's '02 I35, and recently noticed a similar noise. I don't remember hearing it initially, and only noticed it after I had some unrelated work done - a new battery at a Sears Auto Center.

A very definit ticking sound, but it seems to only appear at idle. Any amount of throttle and it is not noticeable. Car has been driving well, but not used too often. Car is just coming up on 80k and was very lightly used past 4-5 years.

Is your noise only audible at idle? Would this do any harm?

[DK SPL Audio]

Don't get me wrong, mine is very loud, not a slight ticking or anything. I haven't started the car in awhile due to fear of damage, but last time I did my gas pedal wasn't even responsive. I think we may be referring to different issues. Before this all started the car was driving fine however.

[ThePirate]

Best of luck with it.

[NutriaforBreakfast]

Since it is really loud and the noise is not going away the timing chain might jump off or onto another tooth
I would fix this-you might just need another tensioner OR more parts/service
I have put a new tensioner on through the "hatch" before
if it is not starting then the chain may have already jumped
If the car is smoking black smoke or white smoke and burning oil there might be engine damage
First thing is to check and see if the crank pulley top dead center mark and #1 piston position agree
You might use the FSM or Chiltons procedures to verify

[Humpty]

Is the check engine light not on? I would imagine if it was an oil viscosity issue the light would be on. The loud knocking could be a connecting rod and for your gf's sake I hope it's not.