1994 Jeep Wrangler sparkplug blown out of engine block

SGT_MARK

MEMBER
1994 JEEP WRANGLER

Engine Performance problem
1994 Jeep Wrangler 4 cyl Four Wheel Drive Automatic

Recently (July 08) I did a driveway tune-up.
Using Champion brand sparkplugs. Fairly routine.
Today (09- 10-08) the second sparkplug back
from the waterpump just came out of the
engine block as I started the motor. I don't know why. I'd been driving prior to this event. On my second start I heard a backfire sort of pop from under the hood, when I raiised the hood the sparkplug was still attached to the plugwire its just that the motor sort of spit it out! Why? Did I do something wrong? I had a strange idel a few days ago and realized the same sparkplug was loose in the block. I purchased Autolite plugs inorder to replace the Champions, the gap on "champs" didn't seem to match the "autos" -did I get the wrong plugs back in July or may my problems only be starting?

1 Reply

ROB2008

MECHANIC
258 POSTS

First of all Screw the spark plug back in . If it just keeps spinning over and over while you trying to get it tight , then the spark plug thread might be stripped. Possibly from over tightening or when you had the plugs installed they might have been were cross threaded.

The Fix:

Ok, this is what you do. Making sure the piston on the compression stroke (and you can tell this by using a flashlight and looking in the sparkplug hole and seeing the top of the cylinder, or by inserting a long bladed screwdriver in the spark plug hole and turning the engine watch the screwdriver being pushed out of the hole) the reason you're doing this is to minimize the metal chips from going into the cylinder therefore scouring the cylider walls. Next, purchase a HELI-COIL brand THREADED INSERT (bye the one kit made especially for spark plugs. The kit consists of 1- helicoil tap 1- helicoil drill 1- helicoil stainless steel threaded insert)
once you have the kit, drill out the old threads in the cylinder head. Use a blow gun with your air compressor to blow out the chips caused by the drilling of the threads. Next using a light oil, coat the tap and tap the hole. Blow out any chips that may have gotton into the cylinder head. Install the helicoil insert. Then procede to install your sparkplug. NOTE THE MOST CORRECT WAY OF PERFORMING THIS JOB IS TO REMOVE THE CYLINDERHEAD!