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brownjeff
brownjeff, ASE Certified Technician
Category: Jeep
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Experience:  17 years experience, ASE certified, dealership certified, Service Manager for 15 years,
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how do you change the spark plugs on a 1999 jeep grand che

Resolved Question:

how do you change the spark plugs on a 1999 jeep grand cherokee?
Submitted: 5 years ago.
Category: Jeep
Expert:  brownjeff replied 5 years ago.

I will attach instructions on how to change. If you still need help just reply, if not click ACCEPT when we are done.

 

Thanks,

 

JB

 

SPARK PLUGS

REMOVAL

On the 4.0L 6 - cylinder engine, the spark plugs are located below the coil rail assembly. On the 4.7L V - 8 engine, each individual spark plug is located under each ignition coil.

  1. 4.0L 6 - Cylinder Engine: Prior to removing spark plug, spray compressed air around spark plug hole and area around spark plug. This will help prevent foreign material from entering combustion chamber.
  2. 4.7L V - 8 Engine: Prior to removing spark plug, spray compressed air around base of ignition coil at cylinder head. This will help prevent foreign material from entering combustion chamber.
  3. On the 4.0L engine the coil rail assembly must be removed to gain access to any/all spark plug. Refer to Ignition Coil Removal/Installation. On the 4.7L V-8 engine each individual ignition coil must be removed to gain access to each spark plug. Refer to Ignition Coil Removal/Installation.
  4. Remove spark plug from cylinder head using a quality socket with a rubber or foam insert.
  5. Inspect spark plug condition. Refer to Spark Plug Conditions.

CLEANING

The plugs may be cleaned using commercially available spark plug cleaning equipment. After cleaning, file center electrode flat with a small point file or jewelers file before adjusting gap.

CAUTION: Never use a motorized wire wheel brush to clean spark plugs. Metallic deposits will remain on spark plug insulator and will cause plug misfire.

ADJUSTMENT

Check spark plug gap with a gap gauge tool. If the gap is not correct, adjust it by bending ground electrode (see picture)Never attempt to adjust gap by bending center electrode.

INSTALLATION

CAUTION: The 4.7L V - 8 engine is equipped with copper core ground electrode spark plugs. They must be replaced with the same type/number spark plug as the original. If another spark plug is substituted, pre-ignition will result.

Special care should be taken when installing spark plugs into cylinder head spark plug wells. Be sure plugs do not drop into plug wells as ground straps may be bent resulting in a change in plug gap, or electrodes can be damaged.

Always tighten spark plugs to specified torque. Over tightening can cause distortion resulting in a change in spark plug gap or a cracked porcelain insulator.

  1. Start spark plug into cylinder head by hand to avoid cross threading.
  2. 4.0L 6 - Cylinder Engine: Tighten spark plugs to 35-41 N·m (26-30 ft. lbs.) torque.
  3. 4.7L V - 8 Engine: Tighten spark plugs to 27 N·m (20 ft. lbs.) torque.
  4. Install ignition coil(s) Refer to Ignition Coil Removal/Installation.

Customer: replied 5 years ago.
hoe do i remove the rail?
Expert:  brownjeff replied 5 years ago.

IGNITION COIL - 4.0L ENGINE

REMOVAL

A one-piece coil rail assembly containing three individual coils is used on the 4.0L engine The coil rail must be replaced as one assembly. The bottom of the coil is equipped with 6 individual rubber boots Ignition Coil Assembly - 4.0L 6 - Cylinder Engine to seal the 6 spark plugs to the coil. Inside each rubber boot is a spring. The spring is used for an electrical contact between the coil and the top of the spark plug. These rubber boots and springs are a permanent part of the coil and are not serviced separately.

  1. The coil is bolted directly to the cylinder head. Remove 4 coil mounting bolts Ignition Coil Rail Location - 4.0L 6 - Cylinder Engine
  2. Carefully pry up coil assembly from spark plugs. Do this by prying alternately at each end of coil until rubber boots have disengaged from all spark plugs. If boots will not release from spark plugs, use a commercially available spark plug boot removal tool. Twist and loosen a few boots from a few spark plugs to help remove coil.
  3. After coil has cleared spark plugs, position coil for access to primary electrical connector. Disconnect connector from coil by pushing slide tab upward Ignition Coil Electrical Connector - 4.0L 6 - Cylinder Engine After slide tab has been positioned upward, push in on secondary release lock Ignition Coil Electrical Connector - 4.0L 6 - Cylinder Engine on side of connector and pull connector from coil.
  4. Remove coil from vehicle

INSTALLATION

  1. Position ignition coil rubber boots to all spark plugs. Push down on coil assembly until bolt bases have contacted cylinder head
  2. Install 4 coil mounting bolts. Loosely tighten 4 bolts just enough to allow bolt bases to contact cylinder head. Do a final tightening of each bolt in steps down to 29 N·m (250 in. lbs.) torque. Do not apply full torque to any bolt first.
  3. Connect engine harness connector to coil by snapping into position. Move slide tab downward Ignition Coil Electrical Connector - 4.0L 6 - Cylinder Engine for a positive lock.

Customer: replied 5 years ago.
..what is the gap setting for the plugs..sorry, i forgot to ask before.


Peter
Expert:  brownjeff replied 5 years ago.

The gap is .035 in.

 

Please click ACCEPT when we are done as I don't get paid until you do.

 

Thanks,

 

JB

brownjeff, ASE Certified Technician
Category: Jeep
Satisfied Customers: 13885
Experience: 17 years experience, ASE certified, dealership certified, Service Manager for 15 years,
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