wierd sound from the head

[danielsan]

well today after doing some diagnostic work ( testing knock sensor with resistor) my head is making a rattling noise. sounds like a loose metal in the head. i have not taken the valve cover off to see if something is loose or broken. though the car runs and idles like normal. just makes a loud metal rattle noise after 1,500 rpms. i hope at worse its a sticking valve.

its not the timing chain as the sounds originates from the 3-4 cylinder areas. i used a screw driver to help listen to where the sound was coming from but i couldnt really pin point the source.

i will get a video clip tomorrow for you guys.

[danielsan]

never mind guys it was a loose spark plug. but it scared the crap out of me, i though i had broken something on the valve train.

[rockinthefans]

yeah i tried that resister trick with my car today. didn't notice any difference really. used a 1 megaohm 1/2 watt resistor. tell me how yours goes.

[danielsan]

i used a 470k ohm 1/2 watt resistor and it worked perfectly.

they noise is back, i retightned the spark plug and it went away for a minute and its back. so i think i have a bad spark plug....i hope.

[yoesh1]

Is it a steady sound pattern or is it kind of random? Does the frequency of the sound increase as you increase the RPMs?

[danielsan]

it sounds almost like pinging but has a squeaking sound to it, almost sounds like an exhaust leak, hence why it think its the plug. also the plug has deposits on it that none of the others have. the deposits are metal erea between the threads and the cermic. im running ngk oem. its not pinging though because its still there when i retard timing all the way and im running 91 octane.

under the valve cover everything looks good. cam lobes are clean and smooth, no foreign objects in there.

no strange idle, no loss of power, runs like normal. sounds does not increas with rpm. its a steady sound. though my exhaust smells like fire crackers though.

here is a pic of the suspect plug (#4cylinder) to #3 cylinder plug, by the way the rest of the plugs look like #3. #4 is on the right.

[BoredDSM]

Really bad corrosion on those plugs. Are the spark plug threads ok? What do the tips of the plugs look like?

[danielsan]

tips look fine, no build up and are clean. threads are good too.

sound only appears after its warmed up i noticed. doesnt change in speed with rpm.

[gvenkat]

Check the threads in the head. Are they still good?

[danielsan]

threads are fine. just that one spark plug looks like that, the rest look like brand new. the bad one was covered in dark brown powder, i cleaned it up and re installed and then decided to take pics.

[BoredDSM]

hmm maybe the heat after warming up is causing ur head to expand? but that would make the plugs expand to so it shouldnt be getting loose. do the plugs still keep sliding out?

[danielsan]

well i drove my car all day, no choice i have to for work.

so now i think its either the chain or my spark plug theory. i moved the plug to the #1 cylinder. yes the sound now sounds like its coming from the front. i will take the easier cheaper route and replace the plug.

[zstylelowrider]

mine did that for a while and i fixed mine by tightening up the caps for the cams. one had worked it's way loose and after tightening it i haven't heard the noise since.

[danielsan]

i found that my lower belt that turns the a/c is over lapped to the compressor side. and i think the noise is coming from the idler pulley. i hope this is causing the noise for the love of god.