knocking sound coming from head

[mspiegle]

sorry.. i feel rather newbish making this post, but i haven't done much work on engines.

Recently... within the past day, i've noticed this extra sound coming from what appears to be the rearmost portion of the head. It sounds much different than all the other engine noise... almost like tapping on a piece of wood. It does follow RPMs, but it sounds slightly different at idle than at 2K rpms. Its definately not my injectors. My car doesn't "feel" like its at a loss in power.

Anyways... I didn't want to... but I threw a bottle of rislone in and that didn't do jack shit so i'm gonna pull the valve cover.

I plan to do a valve adjustment while i'm in there, and see if I can figure out what broke/came loose. So, my question is... What do I look for while under there?

[mspiegle]

also... is there anything I can upgrade/replace while i'm in there that doesn't take too much time or special tools? I drive the shit out of my car... probably hit redline 6-7 times a day just going to work and back.

thanks in advance!

[pig4bill]

Check for hex head bolts.

[kowalski]

the knocking is most likley your valves, also i agree check for hex bolts if not you can change them 1 by one.

[mspiegle]

Alright... so I pulled the valve cover off to take a look around. I don't have the hex head bolts, so I guess i'm good there. I poked around for loose eccentrics, but didn't see any. There was 1 that was slightly looser than the others, but still pretty tight. The eccentrics are the things that attach to the rocker arms which allow you to adjust the valve clearances - right?

I took a short shitty video with my cellphone. You can hear the noise when the engine comes down from a rev, and you can hear it more towards the end of the video. I'm starting to think it *might* not be coming from the head... its more like a woodpecker sound now that I think of it. I'm kinda hoping its something I can fix through the valve cover because anything else will be a pain-in-the-ass.

The car hasn't had a valve adjustment in AT LEAST 40K miles... how often should they be adjusted? Is there any way a valve adjustment issue could cause this strange sound? I would have done the adjustment when I pulled the cover, but I had to leave right away.

https://raptor.nauticaltech.com/~mspiegle/videos/funny_sound.mov

(must download via https!)

[kowalski]

k well i havn't lsitend to the video but seeing as the rockers are supposd to be tightend down to a couple thow can't remember exactly if one is a little loose its verry much needing adjustments so yes that one will be your noise, i believe your suposed to adjust them every 30-40 thousand arn't you? anyways get that adjusted and then your problem should subside.

[BS87]

Broken rocker arm? i dunno, hard to tell from a camphone video.

[mspiegle]

rocker arms appear to all be intact. I'm sure i would definately feel that something was wrong with my car if a rocker arm was broken.

[surebimmer]

Sounds strange but hard to tell from the video. Adjust the vavles and see if this helps. Check a exhaust leak. Also what phone do you have that take that clear of video?

[DEV0 E30]

Sounds like a god damn rooster in heat, got any mechanic friends who have neat doodads and computers?

[kowalski]

that sounds like a mean exhaust leak, check header gaskets (i finaly listend to the video) and adjust the lifters its hard to tell adjust the lifters and if its still there its an exhaust leak. check the little nuts on the manifold if you have them for the air fuel mixture testing as well because they might be loose. also the hex bolts are bad the good ones are the torx bolts. the hex ones have problems breaking. only change them if your going to take them out dont bother if they're already in there.

[rede30]

I put new spark plugs in a while ago and forgot to tighten one down, it started making a noice like that intill i figure out what it was. you can check all the plugs.

Dustin

[mspiegle]

well, i didn't change anything before the problem started happening, but I'll definately checkout some of those ideas. I never would have thought about an exhaust leak, but that's also easy enough to check (replace the O2 sensor about 2 months ago). I bought feeler gauges today, so i should be getting that valve alignment done soon.

The phone is the Samsung A680. It was Samsung's best for a while... but now they're practically giving them away with plans (pisses me off... i paid over $300 when it first came out)

Thanks!

[Marvin_Hecht]

Any follow up or conclusion? I have the exact same problem which started a few days ago--stacatto woodpecker sound from rear of engine, near the idle control valve. Thks for any follow-up. Marvin.