About 2 days ago, my cobra developed a rather sinister knocking sound under certain conditions. I first noticed it idling next to a concrete wall where the sound was bouncing into my open window. The only way to describe it was it sounded like someone using a hammer really far away or something. That's what i actually thought it was, until i turned off the car and it went away. I didn't give it too much thought, thinking a bolt had worked itself loose and something was rattling a bit. The sound was irregular, and not maintaing rhythm with the engine, so i did not suspect anything internal.
Then tonite driving home, I started to get worse, becoming audible idling at traffic lights without necessarily having a wall to reflect the sound into my open window. At first it didn't seem to be RPM dependent, but now ocassionally it does. And just now, as i was coming up the steep hill that i live on, i held the RPM's steady at around 1800-2000 in second and kept steady speed up the hill... the knock was audible the whole time, in a steady rhythm. Prior to that, it seemed to only be present while idling clutch in, or just starting forward motion, or right after upshifting (but not downshifting).
All that being said, for as bad as it sounds, the engine runs as smooth as it ever has (if you could't hear the noise, you wouldn't think anything was out of the ordinary), it's not down on power at all, and isn't smoking or anything. Everything's completely normal except this evil sounding knock.
Here's what i've been thinking:
1. these alloy cobra blocks seem to be notorious for nuts and bolts working themselves loose (i've had trouble with everything from coil cover hold downs to engine mounts!). so maybe something has gotten loose and is rattling now under certain conditions.
2. the knock is some sort of clutch chatter, as it seems to be at least loosely associated with shifting gears and clutch action. Also, my clutch has been suspect lately anyway (it's the original with close to 50k miles on it) with occasional burning clutch smell.
3... well those two are really all i've thought of... PLEASE HELP!! any ideas? suggestions, comments? I guess what i am hoping for is for someone to say, "oh yeah, i know exactly what you're describing, that happened to me and it was (insert part here) rattling against (insert other part here)" but i'll listen to any ideas at this point... *crosses fingers hoping it's not a rod bolt, or some other catastrophic internal damage*
Thanks in advance
Glenn
Then tonite driving home, I started to get worse, becoming audible idling at traffic lights without necessarily having a wall to reflect the sound into my open window. At first it didn't seem to be RPM dependent, but now ocassionally it does. And just now, as i was coming up the steep hill that i live on, i held the RPM's steady at around 1800-2000 in second and kept steady speed up the hill... the knock was audible the whole time, in a steady rhythm. Prior to that, it seemed to only be present while idling clutch in, or just starting forward motion, or right after upshifting (but not downshifting).
All that being said, for as bad as it sounds, the engine runs as smooth as it ever has (if you could't hear the noise, you wouldn't think anything was out of the ordinary), it's not down on power at all, and isn't smoking or anything. Everything's completely normal except this evil sounding knock.
Here's what i've been thinking:
1. these alloy cobra blocks seem to be notorious for nuts and bolts working themselves loose (i've had trouble with everything from coil cover hold downs to engine mounts!). so maybe something has gotten loose and is rattling now under certain conditions.
2. the knock is some sort of clutch chatter, as it seems to be at least loosely associated with shifting gears and clutch action. Also, my clutch has been suspect lately anyway (it's the original with close to 50k miles on it) with occasional burning clutch smell.
3... well those two are really all i've thought of... PLEASE HELP!! any ideas? suggestions, comments? I guess what i am hoping for is for someone to say, "oh yeah, i know exactly what you're describing, that happened to me and it was (insert part here) rattling against (insert other part here)" but i'll listen to any ideas at this point... *crosses fingers hoping it's not a rod bolt, or some other catastrophic internal damage*
Thanks in advance
Glenn
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