So i got this noise commin from the engine. I have narrowed it down to exhaust side of cylinder #4 (next to distributor). It sounds like there is a marble attached to a rocker and it is slapping something. Can’t really hear it at idle, gets real noticable between 2000-3000rpm, then other noises begin to obscure it at higher rpms (just the usual induction howl and so on).
I pulled the plug wire from that cylinder and ran it at that speed and the noise is still there (from what i’ve seen in the archives this is a ghetto check for spun bearing) so i assume i am clear of that known problem.
Did a compression test, 176, 174, 185 and 170psi cyls 1-4. While #4 is low it is closer to the average than #3. Variance goes like this -1.3, -0.1, 5 and -3.5%. The difference between 3 and 4 (the bad/ugly whatever) isn’t even 10% so i’m assuming my combustion chambers seal OK and i don’t have a burnt valve.
Recently at the Chicagoland Dyno day he posted a 113hp and change.
So whaddaya think.
My guess at the moment is a blown lifter or messed rocker (shims maybe). I am ready to pull the valve cover off. Lookin at my Chiltons *flamesuit on* i see that replacing any of these components will require pullin the cams. Since i don’t want to mess anything up and see no need to dissasemble more than i have to, can i just pull the exhaust cam or do i need to pull both as a pair. Priority #1 will be to secure the timing chain to the sprockets not to lose timin (zip ties i assume).
Also would anyone from the Chicagoland area be willin to visit and lend a hand, some moral support and/or some expertise?
This weekend?
Finally does anyone in the area have any of these parts lyin round? I can order them no problem (cash wise) but i am assuming it will take some time to get here.
TIA

Paul,

Nice to see another forum member from Chi-town. Born and raised there myself on the southside... Anyways, have you done a leakdown test yet? Compression looks ok, but maybe it's a valve seat going bad? I don't think you'll be able to see that with just the VC and cams off. Or maybe you got something rattling around in there, eek! Or maybe it's something simple as a lifter not getting pumped up. Try driving on the highway in 4th gear for 10 minutes or so and see if the noise goes away. I had a loud ticking sound coming from my motor once and this ended up being the problem. A good romp on the freeway and the noise never came back.

Oh and have you ghetto-tested all cylinders for spun bearings? #4 usually doesn't go, it's usually #2 or #3 for some reason. It's really hard to pinpoint funky noises without a stethoscope.

Just some thoughts, hope that helps.

paul,
i had some weird ticking sound from my car after i replaced the *intake* cam - it was very noticeable and did not go away or get drowned out at high rpms. it turned out, i displaced one of the shims (cylinder #1) when working on the camshaft. i'm not sure from what you've described that it is a shim problem, but if you do take decide to remove the cam shaft, be very careful with using the zip tie method. for one, the shafts are a bitch to take off - they're torqued on pretty tight. and once the shaft finally decides give way, the sprockets can easily be moved in a way as to cause a skip in the timing chain. i would suggest both the white out and zip tie method. also, make sure that you count exactly timing 20 rollers between the two markers on hte sprockets (assuing you're talking about an sr20de engine). anyways, hope this helps and good luck!

Thanx for the suggestions w/ my noise. I got lucky and was able to score a valve cover gasket on Sat @ a $tealer 15min from home.
This allowed me to get the cover off for a look see and put it back together w/o worrying bout the old gasket causing the almost inevitable leaks.
Didn't look pretty under there. The oil had obviously been cooked at some point. Everything was dark brown if not black (yuk), well except for the camshaft lobes (whew). While they may have suffered some xtra wear at some point they seem to have been lubricated well lately. No scratches or rough spots, very shiny. The rest of the valve train looked as it should; all the shims, rockers and v springs in place and taut. The chain looked ok as did the guides and tensioner (it should, i replaced the original a year ago) AND at TDC the timing marks were in place. Not having an FSM or the time to whip out a feeler gauge and seeing nothing obvious i just cleaned up the cover (all this werk and no improvement? no way) and popped it back on. For good measure i did poke out the cam spray bar holes w/ a bent safety pin and then bathed the lobes, rockers and lifter wells in fresh Mob1 10w/30.
BTW, i threw a vacuum guage on a month or two ago. Forget the exact numbers but the results were generally acceptable. Oh well. Now that i'm relpying i do realize that i have yet to ghetto test for spun bearings on 1-3, first thing i will do when i get a few minutes.
Unless it gets noticably worse, i am goin to let it be. But, i will put S3ish cams w/ new lifters and spray bars on the front burner. More bench/non-invasive-test trouble shooting is on the way, but that's gonna be another set of posts.
Also my experience w/ a Place Racing WAI (CAI ordered but i only did a partial install) that night is another post. The install didn't go smoothly, but it was worth doing it. Did i mention i finally finished @ 2am, THEN go to AutoX school w/ das BimmerNuts the next morning. Ok maybe a few more posts.
Thanx again for the help guys.

The G20 i got has the same problem, i have to get it register. Flush the oil. SEe if the problem goes away

Paul, you got rod knock. It happens to ALL of us at one point. I think almost everyone on the forum spun a bearing and fixed it or went 10:1.

My friend just spun a bearing this weekend. Guess who he is calling. 800-598-3535 (yall know the number) :)

I think almost everyone on the forum spun a bearing and fixed it or went 10:1.

Ya mean Swap in a JDM or euro Primera?
I may still play w/ the oil, changing again very soon. Maybe up visc to 10w/40 allowing for the engines age. Start seriously thinkin bout what i may want to swap in all the same. I wanna stay all motor ***. Hey, i may have time to get it built.
Anyone goin to the Chi-town picnic on Sat can take a listen.

Paul

Oh my face is sooooo red now. At the all out Nissan chi-town picnic, Steve (aka blackb13) and others were pokin round my engine bay. He noticed that my AIV (?) bracket was a little loose allowing it to slap into the valve cover. Held steady my very worrisome clackin went away. WHEW.
Then i turn around and diagnose Ryan’s (aka RySE-R) blown starter as a broken alternator bolt, the one that holds it to the adjusting bracket.
The lesson keeps being relearned: Step away take a deep breath or two and check the basics, Again.

Paul