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Unread 04-11-2013, 01:51 PM   #1
AVR2
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1993 ZJ 
 
Join Date: Apr 2007
Location: UK
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Spark plugs - torque wrench, or finger tight plus quarter turn?

I'm going to change the plugs in my 2005 KJ for the first time over the weekend - I've always had it done by a garage before. I have the Mopar plugs, and there's a little diagram on the box that seems to be indicating that you should get them finger tight and then a quarter turn with the ratchet.

Is that the best way, or should I use a torque wrench? (I'm assuming that there's a torque spec in the FSM, just haven't looked yet). I'm used to using a torque wrench for plugs, but then I've only changed them on the iron-head 4.0L before, not an aluminium head.

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Unread 04-11-2013, 02:19 PM   #2
jbarthol
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2005 KJ Liberty 
 
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Make sure they are the same model number as that identified on the sticker. I hand tightened them, then a half turn after that.
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Unread 04-12-2013, 10:39 AM   #3
Georgeandkira
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Join Date: Sep 2010
Location: Hackensack,NJ
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Apologies Ahead of Time....

Hello, Sorry to sound like an authority figure. I'm brand new to Liberties. I've yet to see the plugs; so I'm learning too. Try to find a torque value or other spec for plugs in an aluminum head. The box many spark plugs came in had a pictogram. Plugs with a crush gasket had a quarter turn (90) picture. You could turn them more but why do that? Bevel edged, non-gasketed plugs had an eighth turn (45) picture. Anyone would have to be nuts to go more. I'd make darn sure of any instruction to go a half turn (180) beyond contact; ESPECIALLY in an aluminum head. Like I said, you can crush a washer way-way down if there is one; but why do that? I never had any problem following the 1/4 turn-1/8 turn guideline. Feel free to sign on and call me names. Kira
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Unread 04-12-2013, 10:52 AM   #4
jbarthol
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2005 KJ Liberty 
 
Join Date: Nov 2012
Location: Cedar Falls, Iowa
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This is what NGK instructs to do.
"4. Tighten the spark plug finger tight first until the gasket reaches the cylinder head, then screw about - turn more with a plug wrench. (Conical seat; about 1/16 turn more)."
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Unread 04-12-2013, 11:20 AM   #5
DaveJKJ
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I always snug mine up by hand and then snap my ratchet on the extension and 1/4 turn.
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Unread 04-12-2013, 02:03 PM   #6
AVR2
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1993 ZJ 
 
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I checked the box again, and it actually says to get the plug finger-tight and then a half- to two-thirds turn with the ratchet. These are the proper (overpriced) Mopar-branded plugs from the dealer.

So I gave them all a half-turn.
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Unread 04-14-2013, 05:01 PM   #7
Eicas
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2006 KJ Liberty 
 
Join Date: Apr 2013
Location: University Place, WA
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I use a torque wrench.

Too loose and the plug runs hot from inadequate heat transfer, or may leak, too tight and you damage the internals and throw the gap off. Why take a chance?

I never install a plug without checking the gap, my last new set varied, - so all but 2 had to be adjusted.
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Unread 04-19-2013, 11:44 PM   #8
DarkSport11
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2011 KK Liberty 
 
Join Date: Mar 2013
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I tighten mine by hand with a socket that has an extension attached to it until the plug seats against the head and then I tighten it to specs with a torque wrench.
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Unread 04-20-2013, 06:47 PM   #9
Trombino
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I believe the FSM says 20 ft. lbs. and don't forget to use some anti-seize compound.
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