Spittin' Sparkplugs

[Gold Bob]

A little history,
I did a minor tuneup at 98,000 miles (air filter, fuel filter, spark plugs) and noticed an improvement in gas mileage.
Around 100,000 miles I noticed a ticking sound from the engine. It sounded more like a dirty injector than a lifter. One of the firefighters at my department happens to be a senior mechanic for the local Ford dealership and said it was valvetrain but not to worry until it got worse. That was Tuesday night.

Well, it got worse. Driving down the highway at 7pm and the truck starts making a thwumping noise. Kind of like a tire separating or a belt slapping. I pull over, the wife has a fit and the 2 year old in the back could care less. I open the hood and what do I find?

A spark plug is laying on the intake. I have one of the engine covers installed and it is quite dark by this point, so I am not sure of the extent of the damage. The plug itself seems okay. The electrode is smashed flat but the threads are perfect. Not one tiny trace of aluminum (the heads are aluminum, correct?), no burrs or any other problems. Hopefully it just worked itself out and the electrode damage came from the ejection.

Thankfully I was able to bring a trailer to haul the truck home. I was even able to drive the ex onto the trailer.

Well, theres my story. I have never had an engine spit out a sparkplug. And the fact that the threads are so clean seems promising.

Jeremy

 

[millerman23]

Well whats the question. put a new one back in and tighten down the rest. hope it dont happen again.

 

[James909]

What engine? 4.6 liter? I hope that the spark plug just came loose. But the 4.6L engines do have a problem where the spark plugs blow out of the heads. They will usually tick like you mentioned right before the threads let go. Inspect the damage and keep us updated.

 

[Gold Bob]

Yeah, its the 4.6. Im going to check it out tonight.

 

[Curtis]

Never heard of a plug blowing out before. But since I have a 4.6 and so does my dad I'll be watching this thread.

 

[rrgone]

Not very common at all in the Explorer 4.6 but used to be a problem (maybe still is?) in the F150s. Here is a pretty good post from a couple of months ago about this happening in an Explorer:

http://www.explorerforum.com/forums/showthread.php?t=230685

Good luck. Let us know how it turns out.

 

[Glen4X4]

Try putting a new plug in and see if it tightens, I hope your threads in the head didn't strip out...if they did, napa sells a kit so you can re-tap the sparkplug hole and insert a coil to hold the spark plug in its hole.

 

[Gold Bob]

Yeah the threads are gone. I ordered a thread insert kit. This is common enough that there are tools make for this specific repair on ford modular engines. I ordered one made by CalVan tools ($250).

I also got to order a borescope (I always wanted one, but couldn't justify the expense).

I thought about going with the kits at the local parts store, but I wanted something a little beefier and this kit is almost foolproof. I thought about the Lisle kit, but its twice the price.

I will try to document this repair. I should have the kit Monday or Tuesday.

Jeremy

 

[Gold Bob]

Fixed

Well, I was able to make the repair in just a few hours. It was a little scary drilling into my cylinder head, but the kit was almost foolproof.

I know I said I would document this, but I got in a hurry and forgot to take pictures.

I started by removing the engine cover (I think the cover actually kept the damage to a minimum as the blown sparkplug was still sitting on the intake).

Next, I removed the broken coil.

Since this was the No. 7 cylinder? (third one back on driverside), I only had to remove the PCV tube to get clear access to the sparkplug hole. On a side note, I did depressurize the fuel rail. Its just habit when working near the rail and injectors.

Next, I used the ail tool provided in the kit to determine the valves were closed and bumped the starter until the piston was at the bottom of the cylinder. I will say that the tool was a little cheesy, but after a little trial and error, I felt comfortable with the position.

Next, I inserted the guide after a liberal coating of lubricant and proceeded to drill out the hole. I bought a new 3/8 air ratchet to use with the drill bit. I think an air drill may have worked better, but the drill bit had a 1/2" bolt head made to be used with the ratchet. I will also recommend using a good compressor (mine barely kept up). The drill bit has a stop built into it to prevent dropping it into the cylinder.

Now the fun part. Getting the shavings out of the cylinder. I used an air gun with a piece of tubing and it worked very well. Again, a quality compressor would speed this up. I also used my borescope to check the cylinder.

Next, I used the tap to thread the hole. Here is were I had to deviate from the kits instructions. First off, the kit said to use the air ratchet to drive the tap. I am not that brave (or stupid ) and used a regular 3/8 ratchet. The tap is inserted in the guide from the bottom and then placed into the hole. There is a grove cut in the shaft of the tap to mark the depth of the cut. I was worried about dropping the tap into the cylinder so I put a zip-tie in the grove. Worked like a champ.

Next, clean the shavings out again. There were alot of shavings to be cleaned out.

Next, I sprayed the threads with carb cleaner to remove the lubricant.

Finally, I screwed the insert onto the new sparkplug and coated the outside of the insert with JB Weld. This was recomended by the instructions as a way of locking the insert to the head ( I think locktite would work just fine). Then I inserted the plug and torqued it to 25 lbs. Replaced everything and started the engine.

The truck runs great. After I did the last tune-up I was disappointed in the trucks performance. Now that I have good compression in all cylinders, its like driving a new truck.

 

[tackleberry]

good ole 4.6 my vic did same thing....now i own a 4.0 05 XLT it was my last straw. plus my vic needed another intake (300 bucks in parts), RAS replaced (200-400 bucks in parts alone, plus labor), tires, (400 bucks), i just used money for DP and im parting out my vic. inside looks almost barren.

 

[cross6]

good info - that kit does look much better than the cheap helicoil kits at autozone and the like.

 

[tripplec]

How do you get the shaving out of the cylinder? The plug hole is small bored or not.

 

[Gold Bob]

I used the blow gun to blow the shavings out with compressed air and checked the cylinder with the borescope.

 

[tripplec]

The shavings blow out the plug hole with the air nozzle in it?

 

[Curtis]

The shavings blow out the plug hole with the air nozzle in it?

You need one with a long nozzel on it like this... put that deep into the cylinder and as the air flows it it along with the shavings come out of the hole.

 

[Gold Bob]

Yea, that would work pretty good. I used a peice of clear tubing about a foot long attached to the end of the airgun. That way I was able to swirl the hose around inside the cylinder. With a high enough volume of air, the shavings will just fly out of the hole. Safty glasses are a must.