Cross-threaded spark plug threads on 2007 stratoliner 1900. right , rear cylinder. What can be done without removing the head?

It most often happens because a spark plug has become loose and compression begins to escape past the threads. As hot compression forces it way along, the cylinder head becomes very hot and especially with alloy heads, the threads will burn away or melt. Cross threading a spark plug can cause the same outcome.
Often the spark plug hole can be fixed by drilling out or dressing up the hole (cylinder head may have to be removed) and then inserting a helicoil (many sizes). This is a repair object that has threads on the inside (for the spark plug) and an outside surface that when heated up will "weld" itself to the cylinder head. It is a solid repair.

this is for a 3.6L engine, should be the same either way. doesnt seem extremely difficult

1. Turn the ignition OFF.
2. Remove the ignition coil.
3. Use compressed air in order to remove debris from the spark plug cavity.

CAUTION: Refer to Safety Glasses and Compressed Air Caution in Service Precautions .

NOTE: Clean the spark plug recess area before removing the spark plug. Failure to do so could result in engine damage because of dirt or foreign material entering the cylinder head, or by the contamination of the cylinder head threads. The contaminated threads may prevent the proper seating of the new plug. Use a thread chaser to clean the threads of any contamination.

1. Remove the spark plug.

NOTE: Allow the engine to cool before removing the spark plugs. Attempting to remove the spark plugs from a hot engine may cause the plug threads to seize, causing damage to cylinder head threads.

INSTALLATION PROCEDURE

1. Ensure that the spark plug gap is equivalent to the spark plug gap specification. Refer to Ignition System Specifications.

NOTE:

• Use only the spark plugs specified for use in the vehicle. Do not install spark plugs that are either hotter or colder than those specified for the vehicle. Installing spark plugs of another type can severely damage the engine.
• Check the gap of all new and reconditioned spark plugs before installation. The pre-set gaps may have changed during handling. Use a round feeler gage to ensure an accurate check. Installing the spark plugs with the wrong gap can cause poor engine performance and may even damage the engine.

1. Install the spark plug.

NOTE: Be sure that the spark plug threads smoothly into the cylinder head and the spark plug is fully seated. Use a thread chaser, if necessary, to clean threads in the cylinder head. Cross-threading or failing to fully seat the spark plug can cause overheating of the plug, exhaust blow-by, or thread damage.

Tighten the spark plug to 20 N.m (15 lb ft) .

1. Install the ignition coil.

REMOVAL PROCEDURE

1. Remove the ignition control modules.
2. Clean the spark plug recess area with low pressure air.

CAUTION: Wear safety glasses when using compressed air, as flying dirt particles may cause eye injury.

NOTE: Clean the spark plug recess area before removing the spark plug. Failure to do so could result in engine damage because of dirt or foreign material entering the cylinder head, or by the contamination of the cylinder head threads. The contaminated threads may prevent the proper seating of the new plug. Use a thread chaser to clean the threads of any contamination.

1. Remove the spark plugs from the cylinder heads.

NOTE: Allow the engine to cool before removing the spark plugs. Attempting to remove the spark plugs from a hot engine may cause the plug threads to seize, causing damage to cylinder head threads.

1. Inspect the spark plugs. Refer to Spark Plug Inspection.

INSTALLATION PROCEDURE

1. Measure the spark plug gap on the spark plugs to be installed. Compare the measurement to the gap specifications.

NOTE:

• Use only the spark plugs specified for use in the vehicle. Do not install spark plugs that are either hotter or colder than those specified for the vehicle. Installing spark plugs of another type can severely damage the engine.
• Check the gap of all new and reconditioned spark plugs before installation. The pre-set gaps may have changed during handling. Use a round feeler gage to ensure an accurate check. Installing the spark plugs with the wrong gap can cause poor engine performance and may even damage the engine.

1. Install the spark plugs to the cylinder heads.

NOTE:

• Be sure that the spark plug threads smoothly into the cylinder head and the spark plug is fully seated. Use a thread chaser, if necessary, to clean threads in the cylinder head. Cross-threading or failing to fully seat the spark plug can cause overheating of the plug, exhaust blow-by, or thread damage.
• Refer to Component Fastener Tightening Notice in Service Precautions.

Tighten the spark plugs to 20 N.m (15 lb ft) .

1. Install the ignition control modules.

First, I would highly recommend that you also purchase a set of igniton cables and replace these also because you are most likely to have damaged spark plug boots when you remove the boots from the plugs. Trust me...it happens about 95% of the time, and you will be way ahead of the frustration if you are prepaired.

Pull the spark plug boots off of the spark plugs.

NOTE:

Allow the engine to cool before removing the spark plugs. Attempting to remove the spark plugs from a hot engine may cause the plug threads to seize, causing damage to cylinder head threads.

Clean the spark plug recess area before removing the spark plug. (spray brake cleaner and compressed air works well) Failure to do so could result in severe engine damage because of dirt or foreign material entering the cylinder head, or by the contamination of the cylinder head threads. The contaminated threads may prevent the proper seating of the new plug. Use a thread chaser to clean the threads of any contamination.

Screw the spark plugs out of the cylinder head.
Check the air gap at the electrode end of the spark plug.

The specification for the plug gap on your vehicle is 1.524mm (0.060 in)

Place a SMALL amount of nickle-based antiseize compound on the spark plug thread, being very careful not to get any on the porcelain portin of the plug. If you do get antiseize on the porcelain part of the plug, it is imperative that you clean it off thouroughly using brake cleaner and a clean rag, otherwise it could cause cylinder misfires.

Screw the spark plug into the cylinder head and torque to specifications.
The spark plug torque specification for your vehicle is 15 Nm (11 ft. lbs.)

NOTE: Failure to properly torque the plugs can cause severe engine damage. Overtightening the plug can damage the threads in the cylinder head and/or make spark plug removal in the future impossible. This will cause you to have to remove the cylinder head for repair the next time the vehicle needs service on the spark plugs.
Undertightening can cause the plug to leak compression and damage the threads in the cylinder head. This can result in the plug blowing completely out of the head causing severe cylinder head damage.

When replacing the ignition cables, make sure they are routed EXACTLY as they were originally routed from the factory. Make sure that all protective wire loom and fasteners are transfered to the new wires and secured properly. Failure to do so can cause damage to the cables, engine misfires and can cause the spark plug wires to "spike" sensitive sensor circuits that are nearby and cause damage to the sensors or your computer modules. Improperly routed ignition cables have also been known to cause interference in radio and stereo systems.

HINT: The rear plugs on your engine are much easier to get to if you remove the two engine struts that go between the engine and the upper radiator support. You can then use a ratchet strap to pull the engine forward to get more room to work on the rear plugs.

no dont force spark plug its trying to cross thread.back spark plug back out.apply thin coat of anti seize compound to spark plug threads.if you have problems getting spark plugs back in a hard to reach place, use a long piece 3/8 vacuum hose about what ever length you need.place vacuum hose over spark plug insulator then install spark plugs to hard reach places to keep from cross threading.if plug tighten 1/4 turn.back out spark plug and try again.dont cross thread or you have to remove cylinder head.if spark plug hole hard to reach to retap or install thread inserts.

you'll have to remove the head, and use a threaded insert kit for spark plugs to cut new threads, and put a threaded insert in for the new threads. These aren't extremely expensive, but you still need to remove the head so you don't get aluminum shavings in the cylinder.

They are underneath the coils,there will be a coil,and under the coil will be a spark plug boot connecting the coil to the spark plug.

2000 Oldsmobile Intrigue V6-214 3.5L VIN H SFI

Spark Plug: Service and Repair
REMOVAL PROCEDURE
TOOLS REQUIRED
J 43094 Spark Plug Boot Puller
1. Turn OFF the ignition switch.
2. Remove the ignition coil assembly.
3. Use the J 43094 in order to remove the spark plug boots from the spark plugs.
NOTE: Allow the engine to cool before removing the spark plugs. Attempting to remove the spark plugs from a hot engine may cause the plug
threads to seize causing damage to cylinder head threads.
NOTE: Clean the spark plug recess area before removing the spark plug. Failure to do so could result in engine damage because of dirt or
foreign material entering the cylinder head, or by the contamination of the cylinder head threads. The contaminated threads may prevent the
proper seating of the new plug. Use a thread chaser to clean the threads of any contamination.
4. Remove the spark plugs from the engine.
INSTALLATION PROCEDURE
NOTE: Use only the spark plugs specified for use in the vehicle. Do not install spark plugs that are either hotter or colder than those specified for the
vehicle. Installing spark plugs of another type can severely damage the engine.
NOTE: Check the gap of all new and reconditioned spark plugs before installation. The pre-set gaps may have changed during handling. Use a round
feeler gage to ensure an accurate check. Installing the spark plugs with the wrong gap can cause poor engine performance and may even damage the
engine.
1. Measure the spark plug gap on the spark plugs to be installed. Compare the measurement to the gap specifications. Refer to Spark Plug Usage.
Correct as necessary.
NOTE: Be sure that the spark plug threads smoothly into the cylinder head and the spark plug is fully seated. Use a thread chaser, if necessary,
to clean threads in the cylinder head. Cross-threading or failing to fully seat the spark plug can cause overheating of the plug, exhaust blow-by, or
thread damage.
NOTE: Refer to Fastener Notice in Service Precautions.
2. Install the spark plugs to the engine.
Tighten
Tighten the spark plug to 20 N.m (15 lb ft).
3. Install the spark plug boots to the ignition coil assembly.


4. Install the ignition coil assembly.

Some basic rules I've learned and all of 20 minutes out of you life. People complain about valve noises or sluggish throttle response, well a crisp set of plugs firing does a lot to resolve these issues and for only $10 (standard plugs) is the cheapest performance mod going.
1) Replace your plugs annually (or at a minumum follow schedule of rear tire replacement) regardless of amount miles.
2) Plain and simple. Don't waste money on iridium because of #1 they spark the same it's just the tips that are suppposed to last longer.
3) Full removal of the tank is not needed but you will need to move it out of the way. Remove seat, remove center speedo and disconnect connectors, remove tank bolts, disconnect vent tube at the front portion of tank, lay a towel across the frame where seat normally goes, lift tank and turn tank sideways it will rest there without removing gas lines underneath, stock air box removal is not needed (BAK is even better for access), not certain what they mean by rider's seat bracket (at the back of the seat?) but obviously this is not needed either. There are wires zip tied to the frame that might need to be pushed out of the way or carefully cut the zip ties and just add new ones when done. (This just allows better access to get to the spark plug on right rear cylinder.)
4) A long screwdriver with small hose on end helps retrieve and reinstall plug on the front cylinder (unless you have very long fingers)
5) Go to auto parts store and purchase a socket with universal swivel for proper angle to losen or tighten plugs
6) A small amount of anti-seize compound on the threads is never a bad thing unless you use too much or it smears across the tips which would probably burn off anyway but that's just sloppy mechanics. (You want to be a sloppy hack like that, well you're outta the club... Go ride another brand.)
7) Use your hand never the socket to start the threads on the new plug. Place new plug in hole near cylinder and spin in reverse to align the threads then go in normal direction. If it does not feel correct at the start - never force it.
8) Do not over torque the spark plugs when tightening.
9) When reconnecting coil wires make certain you press down enough for a positive click to ensure proper connection.
10) Put tank and seat back in place and prepare for the response "why did I wait so long..." on the first ride...
Hope that helps.

The causes for spark plugs leaving the cylinder head are as follows:
1. The threads in the cylinder head were compromised, as in cross-threading.
2. The spark plug, when replaced, was not tightened down properly (like only 2-3 threads in)
3. A combination of the above.

Whe the plugs are fully seated in the cyl heads, and are at the proper torque, it would be extremely RARE for the plug to be jettisoned by the compression of the pistons. You only have roughly 175-185 PSI compression, this will NOT defeat the retention of the threads. Look at the hole in the head...How may threads are damaged? If it is just the end of the hole, the plugs was not in "all of the way". If ALL of the threads are bad, the plug was inserted improperly, and damaged the threads in the head. Rethreading (a "heli-coil") will correct you condition, if properly done.
Hope this helps.