Why does one of the spark plugs(and obviously the wire too) move slightly up and down when the engine is on?

Question

The engine makes a knocking sound from that spark plug too. I haven't had the chance to take it out to look at it yet but im wondering if i should just buy new spark plugs to fix the problem.

Answer 1

You need to try to tighten it before it blows out. The threads in the head could also be striped.

Answer 2

first make sure the plug wire is snug to plug if so try to tighten plug to see if its loose. if not the noise sounds like spark arcing.change plug.

if this doesnt work start car  and crab that plug wire, if it shocks you change that wire..

Answer 3

As all the others are saying I would spend some time researching the issue.

1st. Remove the spark plug lead (without the car running, unless you like thousands of volts going through you!) & inspect it for damage. Signs of a faulty HT lead are black (arcing) marks around the faultly area. This is caused by the insulation deterriorating & the electricity finding an "easier" path to earth. Be careful not to mix up the HT leads if you plan on removing more than one.

2nd. Check the spark plug for tightness. Obviously if the plug was loose then tightening it may solve all your issues. I would remove the plug either way just to inspect it while your spending time under the hood especially if it was loose. Pay special attention to the threads & the condition of the tip. If there is any damage then obviously you should replace it. The colour of the tip is a good indication of how the engine is running to - Black (carbon) = Rich. Too clean & it's running lean. It should be slightly brownish.

3rd. Inspect the threads in the head for damage. Grab a torch & check for any burring or crossed threaded-ness. Any issues in this department will be expensive to repair.

4th. If everything is fine & the plug WAS loose - reassemble. Reseat the spark carefully & tighten to manufacturers specifiacations. Be sure not to overtighten! This will dig you a VERY deep money hole. Once the plug is back in place correctly refit the HT lead. Be sure the lead is gripping the lead nicely & is not loose.

Once everything is correctly reinstalled then start "her" up & see. If the plug is secure & you no longer have the noise you were concerned about then happy days!

Good luck.

Answer 4

tighten up and see. check if the plug socket has loosen.

Answer 5

in that situation, you have one of three possible problems.

one the plug is loose and the compression from the engine is moving the plug.

two, the plug is stripped and moving with the compressed air flow.

three, the head itself is stripped and the compression is moving it.

i would see if the plug is loose first and proceed with caution after that. if you did the last tune up, you could be at fault , but if  a shop did it, locate your last receipt and go back to that shop and talk to the service writer.  

Answer 6

well if you see it move its loose .. so tighten it before it blows out  

Answer 7

NO....don't buy new plugs until you investigate it further.  Check the tightnesss of the plug first.

Answer 8

    If you have the ability to change your plugs, then you could have tightened the obviously loose one by the time you read this

   Whether or not they should be changed is a different matter, dependent on the mileage etc.

   Would you change all four tires if one picked up a nail?

   Sorry to sound so crabby; bad morning...

Answer 9

Right, ask questions first and investigate later.....

Why waste time asking a random question when you haven't even checked the car????

Check the spark plug and then ask a question. Geez.....