just yesterday a wierd tapping noise started to emit from under my hood. i only heard it on start up, three loud taps, then it went away. well today i noticed that when the engine hits 3000 rpm and the throttle is at a certain position, it continues to tap. now if i floor it? nothing, coast? nothing, accelerate? only are about 1/4 throttle does it make the noise. if you keep a steady acceleration then the noise continues up into the rpm range. when i popped the hood to listen to it myself, i had a friend make the rpms jump between 2500 and 3000. it sounded like it was coming from under the valve cover. i just had the valve cover off to get it powder coated, could i have possibly knocked something loose? maybe put it on wrong or got something inside? i also replaced the gasket and the bolts, is it possible i need to retighten the bolts? im gonna try that in the morning. any help is appreciated!
Thanks!:help
wierd tapping noise
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cowboyrps13
- Posts: 191
- Joined: Mon Aug 12, 2002 1:09 pm
- Car: 89 camaro, 89 240 hatch
that sounds charicteristicly like a rod knock, I know not what you wanted to hear but that is how a rod knock starts. when its doing it pull one wire out at a time and see if it goes away, or if you dont mind reseting the ecm and dont want to get shocked pull one injector at a time till you hear the noise go away, be sure to put each one back after testing that cyl. If the noise goes away on one of the cyl that is the one with the rod knock. if it doesnt go away at all try pinching off the pcv fresh air inlet to the valve cover and keep the noise steady for a min. or so if it goes away then it is the piston causing the noise [ wrist pin or piston to cyl slop]
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cowboyrps13
- Posts: 191
- Joined: Mon Aug 12, 2002 1:09 pm
- Car: 89 camaro, 89 240 hatch
well, on my way home from work, the ticking started to get louder(and i mean reallllly loud) and stay ticking continuously through the rpm range regardless of the throttle positon 
when i took it out of gear to coast the car died. i had to get it towed to my mechanic the engine only has 28000 miles on it (rebuilt) and is still under warranty (30000mi.) so im hoping it has nothing to do with my valve cover being off for an extended period of time(i did have the exposed head covered with seran wrap and rags). thanks for the help nistech! hopefully the mechanic can get the problem pinpointed and fixed under warranty. also, what exactly is rod knock? and what are consequences if it went on for an extended period of time?
when i took it out of gear to coast the car died. i had to get it towed to my mechanic the engine only has 28000 miles on it (rebuilt) and is still under warranty (30000mi.) so im hoping it has nothing to do with my valve cover being off for an extended period of time(i did have the exposed head covered with seran wrap and rags). thanks for the help nistech! hopefully the mechanic can get the problem pinpointed and fixed under warranty. also, what exactly is rod knock? and what are consequences if it went on for an extended period of time?-
cowboyrps13
- Posts: 191
- Joined: Mon Aug 12, 2002 1:09 pm
- Car: 89 camaro, 89 240 hatch
rephrase: I meant to say rod bearing not crank shaft bearing. If the engine stopped running that still may not be a good thing it may have been lacking oil pressure at the bearings. They could have rebuilt it and accedently put the bearings on one of the rods wrong not allowing oil in to lube the journal on the crank.