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Discussion Starter #1
Somewhere down the line jeep changed the spark plugs used on the hemi from champion to ngk. Champions were tapered. Ngks have a crush washer. If anyone has the factory service manual for 09-10s, please check what torque the plugs have to be tightened down to. I have the FSM for older jeeps and it says not to exceed 15ft.lb. I don't see how that's enough to crush the washer. The box the plugs came in (mopars) says to go 1/2 turn past finger tight. Will that not be too much? Thanks for the help
 

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Tapered seat spark plugs are usually for iron heads, aluminum heads need crush washers. I've never had a GenIII Hemi, but I'm shock earlier versions had taper seat spark plugs.

15 ft-lbs sounds reasonable for spark plugs in aluminum heads, I'm used to 21 ft-lbs.

A couple of things to keep in mind, you have to use anti-seize with aluminum heads (if you want the head to last) and that will lube the threads a lot, for a torque that is a dry torque. I have stripped spark plug threads in aluminum heads using torque wrenches, its because the anti-seize lubes the threads and you end up putting more pressure on the threads than the torque spec intends.

I go strictly by the box directions of going finger tight and then the fraction of the turn recommended, never stripped out threads that way.

The thread barrel of plugs for aluminum heads is much longer than those for iron heads, to help with the sealing and pressures for a lower torque.

So, only aluminum heads, its not so critical to torque the plugs down tight, in fact if you do, you can damage the head. So I torque them down with a regular ratchet wrench the recommended fraction of a turn, but I also go by feel, you can feel the plug tighten up as it crushes the new washer, once it hits the point it won't turn anymore (close to the recommended fraction of a turn) and it stay still with only a moderate even force with my hand, I know its seat properly.
 

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Discussion Starter #3
Thanks as always Mongo.

NGK website states that flat seat plugs with washers should be tightened to 18-21 ft/lb in an aluminum head. Tapered seat plugs - under 14 ft/lb. thats where it makes me nervous. Chrysler says not to exceed 15 and does not differentiate between taper seat Champions or flat seat/washer NGKs. Yet the box says to do 1/2 a turn past finger tight, which is more than likely equivalent to 20-21 ft/lb.
I tighten them too little and the washer wont get crushed. Too much - and the threads will possibly be stripped. Im planning on doing as you said - going by the box and just turning it 180 degrees. Without knowing the true target value, the torque wrench here in my opinion is dangerous.
 

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For other Jeep People--:> Every now and then it just shuts off while engine is running. How many times do you hear that. About a minute later it will start right back up and wont do it again for months.~~~~~~~~~~~ Also consider if you're using higher than recommended Octane, higher octane fuel has a higher volatility, and doesn't vaporize as easily, especially at cold temperatures. So using higher than needed octane, during cold weather in a cold engine can result in stalling. [ Not my opinion ] ~~~~~~~~~ First thing's first, assume you have a Hemi. Start taking out your spark plugs, and reading the part number. They MUST be Champion P/N RE14MCC4. These are the Champion "570" series copper plus plugs that should be available at most auto parts stores. Now, beyond the part number, there are an unexplained number of these plugs that have a charcoal/black wire-side tip rather than the typical polished silver tip. You MUST have the polished tip plugs, every last one (16) of them. If you have ANY other spark plugs installed in your engine, go to the parts store and get the RE14MCC4 and open every last box to ensure it has a silver tip. The black tipped ones are still in circulation, and are known to be linked to the Hemi stalling, along with any plug other than the OEM, which is the aforementioned Champion plug.
Once you have verified/changed to silver tipped RE14MCC4s, if you still have the stalling issue, we can go on from there.


Skip Weis Yes, worn spark plugs, of even the correct variety can cause these issues too. So check your gap and color on your plugs. Unlike most all modern vehicles that use platinum plugs that are a non-maintenance item until 100,000 miles, Chrysler has insisted on keeping with copper plugs, that require replacement every 30k miles, so keep that in mind. Just the smallest drop of Never-Seaze by Permatex on the spark plug threads and tighten only to 15 ft lb. [REDUCE TORQUE WHEN USEING NEVER-SEAZE BY 25%] Don't strip any threads in these aluminum heads. Threads are long. Sealing is good
 

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NGK website states that flat seat plugs with washers should be tightened to 18-21 ft/lb in an aluminum head. Tapered seat plugs - under 14 ft/lb. thats where it makes me nervous. Chrysler says not to exceed 15 and does not differentiate between taper seat Champions or flat seat/washer NGKs. Yet the box says to do 1/2 a turn past finger tight, which is more than likely equivalent to 20-21 ft/lb.
I tighten them too little and the washer wont get crushed. Too much - and the threads will possibly be stripped. Im planning on doing as you said - going by the box and just turning it 180 degrees. Without knowing the true target value, the torque wrench here in my opinion is dangerous.
IIRC, 21ft-lbs directions say to do a 3/4 turn after finger tight, so 15ft-lbs might just a 1/2 turn after finger tight. (I don't have the boxes in front of me, so don't trust that, do your own homework).

You're talking about the difference between general guidance and specific guidance. You always go with the specific guidance, there may be something different about the Hemi that causes Chrysler to recommend less than the normal torque. The fact the Hemi has two plugs close together may very well be the reason, NOT enough metal in the area to be as rigid and a lower torque is smarter. (a pure guess on my part)

I've always assumed, don't know, taper or flat would depend on how the head is machined. I suppose you can use one in replace of the other, the taper area is small and if the head has a large enough flat area for the plug, I'm guessing it would work. Regardless, if the vehicle came OEM with flat spark plugs, that is what I would go with.

Remember, a spark plug being blown out of the engine by compression and combustion is many, many more times likely to happen from damaged (over torqued/stripped) threads than it is from the plug being to loose.

The spark plug is suppose to be just tight enough, compression and combustion doesn't back them out. So, as you tighten it down, you'll feel the force go up as you turn it, when hit the point that it doesn't move with just a moderate force on the wrench, i.e. it stops and if you want to turn it more, you'll would need to put a whole lot of force on the wrench, that is where you stop, don't crank them down.

Remember, if you use anti-seize (which you should or the threads will be damaged on the next spark plug change) that can drop the torque to tighten by 25%. So if your using a torque wrench, I'd set it to 11ft-lbs, if it clicks while the plug is still turning, and you've hadn't done the 1/2 turn, maybe a little more to you feel the plug stop turning.

I have never encountered a problem torqueing spark plugs to a little less than spec torque (or just the amount of turn recommended on the box). I have stripped out spark plug threads by globbing on a lot of anti-seize then using a cheap torque wrench and torqueing it to the spec torque.
 

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Discussion Starter #6
Ty mongo. I got a response from NGK and they confirmed going about 1/2 of a turn past finger tight. Now the hard part is finding a couple of hours to get the job done.
 

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For other Jeep People--:> Every now and then it just shuts off while engine is running. How many times do you hear that. About a minute later it will start right back up and wont do it again for months.~~~~~~~~~~~ Also consider if you're using higher than recommended Octane, higher octane fuel has a higher volatility, and doesn't vaporize as easily, especially at cold temperatures. So using higher than needed octane, during cold weather in a cold engine can result in stalling. [ Not my opinion ] ~~~~~~~~~ First thing's first, assume you have a Hemi. Start taking out your spark plugs, and reading the part number. They MUST be Champion P/N RE14MCC4. These are the Champion "570" series copper plus plugs that should be available at most auto parts stores. Now, beyond the part number, there are an unexplained number of these plugs that have a charcoal/black wire-side tip rather than the typical polished silver tip. You MUST have the polished tip plugs, every last one (16) of them. If you have ANY other spark plugs installed in your engine, go to the parts store and get the RE14MCC4 and open every last box to ensure it has a silver tip. The black tipped ones are still in circulation, and are known to be linked to the Hemi stalling, along with any plug other than the OEM, which is the aforementioned Champion plug.
Once you have verified/changed to silver tipped RE14MCC4s, if you still have the stalling issue, we can go on from there.



Skip Weis Yes, worn spark plugs, of even the correct variety can cause these issues too. So check your gap and color on your plugs. Unlike most all modern vehicles that use platinum plugs that are a non-maintenance item until 100,000 miles, Chrysler has insisted on keeping with copper plugs, that require replacement every 30k miles, so keep that in mind. Just the smallest drop of Never-Seaze by Permatex on the spark plug threads and tighten only to 15 ft lb. Don't strip any threads in these aluminum heads. Threads are long.


WRONG! Use only the dark tip Champions if using those as a replacement. The same part number with the silver tip is the culprit of many problems. Been there, done that.
 

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Let Me Adjust my Verbage. Spark plugs...

I own a Jeep Commander fitted as one of these two ENGINES
How do I choose what I have ?
4x4, 4.7 L V8 FFV, 5 spd Automatic 545RFE
or...
4x4, 4.7 L V8 MPI, 5 spd Automatic 545RFE

This particular 2007 Commander is E-85 fuel ready and has 8 spark plugs.
Speaking of spark plugs; Under hood lists RC 12MCC4 spark plugs. Brand Champion [not stated]

I have heard that the plugs come copper or platinum, use copper.
Before taking them from the parts house CHECK to make sure they are copper. Part houses mix and match ... so check for copper.

Also look it up here; http://www.factorychryslerparts.com/showAssembly.aspx...


Skip Weis SPARK PLUG. Required~ 008
2007 JEEP COMMANDER Limited 4x4, 4.7L V8 FFV, 5-Spd Automatic 545RFE.
RC12MCC4.

Stock Code SPRC12MCC4 ; 0SP00483; 3555557310; 56028236AA
Manufacturer Chrysler
Categories Electrical > Spark Plugs

4.7L ENGINE PLUG CHANGE

Changing spark plugs on the 4.7 liter engine is relatively straightforward, and in some ways much easier than other engines. The plugs are vertically oriented which makes them a lot easier to get to. This engine is unique in that it has a coil on each spark plug. The coils slip over the spark plug and have a retainer that goes over a stud on the head. The coil must be removed to gain access to the plug. The image below shows a closeup of the coil of the #1 cylinder.

The Factory Service Manual states that you should ONLY use spark plugs with a copper electrode and with the same number and heat range as the OEM plugs or detonation will occur. The factory spark plugs are Champion RC12MCC4. All plugs should be gapped to 0.040"


1.Remove the air hat from the throttle body (8mm bolts on the hose clamps between the air hat and air box, another one on the hose clamp around the throttle body).

2.EACH plug has a coil on it. Use a compressor or a can of air to blow all the debris from around the coil.

3.Unclip the electrical connector by pressing down on the clip on top of the connector and then pulling the connector off.

4.Use a 10mm socket to remove the bolt that holds the coil to the block (CAUTION! Don't drop the nut or you may never see it again!)

5.Twist the coil slightly while pulling up and remove it from the plug. There is an O-ring around the coil. Make sure it is not damaged. If it is nicked or torn replace it. The Mopar part number for the 2000 4.7L engine ignition coil O-ring is 05015297AA and the cost (on 12/03) is about $3.30 each.

6.Use a compressor or a can of air to blow all the debris from around the plug. They are deeply recessed into the head and vertically aligned. Anything in the recess is going to fall down into the cylinder when you pull the plug!

7.Use a standard 5/8" spark plug socket (I highly recommend that you use one with a foam insert that holds the plug!) to remove the plug.

8.Install the new plug and torgue to 20 ft lb. BE VERY CAREFUL when starting the plug and make SURE it does not cross-thread. The plug recesses make it a little hard to mess up, but be careful anyway. The heads are aluminum so do not over-tighten the plugs!

9.If you have some, spread a little silicone grease on the coil O-ring. Reinstall the coil, and the coil retainer nut. Reinstall the coil electrical connector.

10.Repeat steps 2 - 9 seven more times.

11.Reinstall the air hat and reconnect the tube to the air box.

The number 8 cylinder is the tough one for me. The dip stick tube for the transmission gets in the way of removing the coil and the plug itself is tucked back under the firewall slightly. You'll need a swivel for that one.

Cylinders 3 and 4 are also slightly tough. There are some metallic hoses going across the block (A/C or something, I never really looked). You will need to unclip the retainers that hold them down, and then spread the hoses a bit to be able to get the coil between them.
 

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Well, I can't remember 150,000 miles ago to when I pulled out the original Champion plugs on my '07 hemi and if it had tapered or crush washer seating. The Autolite Iridiums I've been running ever since have crush washers, and I torque them to 13 ft-lbs.
 

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Discussion Starter #10
did the job yesterday. Pretty straight forward. The first plug I did was spinning easily past half a turn and didnt start getting tight till around 2/3 of a turn. So i just snugged it up and moved on. Ended up doing the rest the same way - stopped once it got tight. THe box says 1/2 to 2/3 of a turn, so I should be ok. Not that easy to determine how much of a turn you've made anyway, as the ratchet barely moved 2-3 inches at a time on some plugs.
Having said that, the plugs were a bear to loosen though - had to use a lot more force on the ratchet to get them to move (had to use my breaker bar on 2). Overall, not a bad job. Thanks for all the help.
 

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Hope you used anti-seize on the threads of the new plugs. Its NOT good if the old plugs have so much trouble coming out, thread damage could occur. The anti-seize will prevent that in the future.
 
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