Horrid Petrol thing

[Moose]

Unfortunatly not everything is diesel!
Recently the spark plugs on my Evinruide 9.9 have been loosening off. We put new plugs in while we were in Poole the other week (to try and solve the problem), after a trip round Brownsea Island both plugs were only just hanging in, with the resulting oily goo everywhere. I tightened them up (tighter than normal) and the same thing happened.

Any ideas?

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Moose

 

[DepSol]

use a hammer

<hr width=100% size=1>Dom

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[Kevin]

Hi

could it be that your engine isnt being cooled as it should the engine head getting too hot and expanding (at a different rate to the metal used in the plug) causing it to loosen and vibrate even looser. what makes me think this is that if they tighten down fine when not running then threads etc are fine and when its running its getting a bit too hot.

kevin

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[Moose]

Dont think so, I get the normal strong jet of cold water even after a long run.

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Moose

 

[burgundyben]

threads in the heads are knackered? will need to be helicoiled?



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[DogStar]

Thats what I would think, at some time it may have been cross-threaded. I don't envy you, its a pain in the harse!

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[jon_bailey]

Some heads/plugs are designed to use compressible washers that wil also act as lock washers. Does your engine need these, in which case are there old washers left in the plug seats that could be causing problems?

Alternatively they may need helicoiling.

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[longjohnsilver]

What you need are good quality rubber O rings, just don't pinch them too tight or get em too hot.

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[mainshiptom]

locktite do a product where you put it on the thread and it stops it from turing by vibartion not sue what its called somthing like "nut lock" in a small red bottle shoul be under a fiver !

Tom

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[Colin_S]

Are you tightening the new plugs correctly. They've got a washer that needs to be fully compressed first time they are fitted. Subsequent fitting does not require the same tightening procedure. A rough rule of thumb is finger tight and then a further 90 degrees when new but only 15 degrees when reusing.
If they've been running lose you may have damaged the threads and, as others have suggested, helicoiling the head is the answer.

I've used these in the past to repair damage threads in ally - <A target="_blank" HREF=http://www.recoil.com.au/>http://www.recoil.com.au/</A> They are an Australian product but can be got from most decent motor factors.

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