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Discussion Starter · #1 ·
Recently I noticed a ticking noise when the car was idling rough. By disconnecting the spark plug wire from the distributor cap, one at a time, I was able to isolate the noise down to Cylinder 8. In an effort to troubleshoot, I first swapped the spark plugs wires(#7 and #8). I then swapped the spark plugs #7 and #8. After both of these steps, the problem remained in cylinder #8.

So my question is what could be causing this? I have read a number of different posts suggesting anything from the plug wire going to ground, to exhaust leaks, to very bad internal issues. Of the possibilities, which ones can I rule out since the noise disappears when I disconnect spark plug wire for cylinder 8.

Any ideas/suggestions would be greatly appreciated.

-thanks
Glenn
 

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That. You might also consider taking a length of vacuum hose and using it as a stethoscope to try to isolate where it's coming from. At least you could hear if it is from the valve cover or exhaust.
 

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Discussion Starter · #4 ·
I'd pull the valve cover and looked at the spring/rocket arm/push rod
Thanks for the suggestion. I had already taken off the valve cover and looked at the spring/rocker arm/push rod. I didn't see anything obvious. Also, I figured that if the noise went away when I took away the spark, it couldn't be a loose rocker-arm, could it?

-thanks
Glenn
 

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Could be cylinder 8 isn't getting gas and the tick your hearing from the spark from the plug but I wouldn't leave it disconnected bc then when you do get gas to it it will just pressurize instead of burn

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Thanks for the suggestion. I had already taken off the valve cover and looked at the spring/rocker arm/push rod. I didn't see anything obvious. Also, I figured that if the noise went away when I took away the spark, it couldn't be a loose rocker-arm, could it?



-thanks

Glenn

It sure could. The valve train runs mechanically from cam shaft -> lifters -> push rods -> rocker arms -> valves. Everything still moves as the engine turns, regardless of spark.
 

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Discussion Starter · #7 ·
It sure could. The valve train runs mechanically from cam shaft -> lifters -> push rods -> rocker arms -> valves. Everything still moves as the engine turns, regardless of spark.
Yes, I realize that everything continues to keep running when there is no spark. My point was the ticking stops when i disconnect spark plug spark. Because it stops when pull the plug wire, that makes me think it isn't a loose rocker arm for instance. I was hoping the fact that it doesn't occur without spark, it would help narrow down what the problem is.

-thanks
Glenn
 

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Yes, I realize that everything continues to keep running when there is no spark. My point was the ticking stops when i disconnect spark plug spark. Because it stops when pull the plug wire, that makes me think it isn't a loose rocker arm for instance. I was hoping the fact that it doesn't occur without spark, it would help narrow down what the problem is.



-thanks

Glenn

Sorry, I misread. I think you're correct, if it stops without spark, I would expect it isn't the valve train.

I would guess the next easiest thing to rule out might be exhaust leak, but I'm not sure. A compression test would tell you if you have an internal cylinder issue.
 

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The reason the ticking stops when you remove the plug wire is due to the fact there is no force on the top of the piston from the cylinder firing.


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