spark plugs of cherokee 2004

Old 10-29-2017, 11:12 AM
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Wink spark plugs of cherokee 2004

Hi jeepers,

I have grand cherokee model 2004 , today I start to put new spark plugs on , I discoverd that the new and old spark plugs are of long thread plugs, when I insert and screw the plug in side its hole , it will rmain by half out side the cylinder head !! I s that normal to plugs of jeeps that go down half and remain half of the thread up ??
why dont we put short thread to be normal tighten with face of the cylinder head ??

Fareed
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Old 10-29-2017, 09:44 PM
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You'll have better luck if you post in the Grand Cherokee section
https://www.cherokeeforum.com/f5/
and pics probably wouldn't hurt either.
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Old 10-30-2017, 01:58 AM
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Which engine do you have?
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Old 10-30-2017, 06:06 AM
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Wink spark plugs of jeep cherokee model 2004 engine 4.0

Thank you for answering, I have 4.0 engine !
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Old 10-30-2017, 01:19 PM
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Those spark plugs are the standard 14mm thread and are about 3/4" long. They should thread easily until the gasket hits the head surface. If they don't either they are cross-threaded or someone used short thread plugs in it and the threads need cleaning. They won't seal compression unless the gasket crushes.
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Old 10-31-2017, 08:30 AM
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Default spark plugs of jeep cherokee model 2004 engine 4.0

Thank you dave, thats very kind of you.
Autolite APP
I put and screw the plug right way not cross threaded, but I see that the old spark plugs is tighten to its half way down in its hole ,, and the new goes half way and stop,,, the plugs are Autolite APP 985 , which thread length 3/4 inch and hox drive 14 mm. Engine goes well and drive good !
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Old 10-31-2017, 09:31 AM
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I don't know, guy, but that doesn't sound right to me. I'm using NGK ZFR5N and they screw all the way in. That plug is specified for your 2004 as well.

Personally, I never liked Autolite plugs. They never seemed to work very well in any vehicle I ever owned. That's my opinion.

Maybe you should get someone to clean out the threads anyway before you blow a plug out while driving.
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Old 10-31-2017, 09:44 AM
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Originally Posted by dave1123 View Post
I don't know, guy, but that doesn't sound right to me. I'm using NGK ZFR5N and they screw all the way in. That plug is specified for your 2004 as well.

Personally, I never liked Autolite plugs. They never seemed to work very well in any vehicle I ever owned. That's my opinion.

Maybe you should get someone to clean out the threads anyway before you blow a plug out while driving.
You make a good point Dave. If it was run for any length of time without a plug sunk all the way to the bottom there would be carbon built up on the threads for sure. New plugs will never go all the way now, and these holes need to be "carefully" chased with a special pitch sparkplug hole Tap.
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Old 10-31-2017, 10:31 AM
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Yeah, it's a 14X1.25mm metric thread. I've got a tap right here in my machinist's chest. I've put a lot of compression releases in 2-stroke bikes in my day! I paid around $7 for the tap and charged $15 a head for doing them. I've probably done over 30. Nice little sideline business. This was back in the 70s.

The problem with his jeep is if it's been run long enough with short plugs in it, the threads may be burnt away. I guess it doesn't matter as long as the plugs go all the way in after they're tapped out, although the plugs may run hot.
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