ARGH... #4cyl broken spark plug electrode

[Apollo-Soyuz 1975]

Background: changed spark plugs + wires ~3 months ago. Autolite copper-core spark plugs (#764), Motorcraft plug wire set. Torqued to spec, about 20n-m per the workshop manual. Two weeks ago, the engine developed a slight hesitation under load... I thought probably vac leak, dirty MAF, or dirty EGR. Cleaned MAF, verified vac lines OK... then the truck started running worse last night -- slight tapping sound & threw a CEL. Decided to pull & inspect plugs today... and the #4 cylinder's passenger-side plug had a center electrode + insulator broken off almost 1/2-inch above the bottom of the threaded skirt.

FFFFFUUUUUUUUUUUUUUUU-


My question: what do I need to do to get this thing running healthy again? Should I run a small magnet down in the cylinder to see if there are any pieces to fish out? Run a compression test on cylinder #4? Have a shop look in there with a borescope to check for damage? Just put everything back together and cross my fingers?

 

[Mark_88]

You can try a magnet...but if your seals are good you can put a shop vac over the plug hole and it should lift out anything that a spark plug might deposit in there...

 

[scotts90ranger]

other method would be to take both plugs from that cylinder out and blow air through one side, it should push it out the other side

 

[4b316]

If you ran it like skipping like that for any amount of time it probably blew the pieces out the exhaust.For peace of mind,I would blow it out like Scott said and do a compression test

 

[Apollo-Soyuz 1975]

Thanks for your suggestions
I spent the day taking it apart and replacing both cyl#4 plugs. Did a blow-through procedure -- no debris to be found, thankfully. Installed new plugs in cyl#4, buttoned up everything, and fired 'er up... the idle is still kind of lumpy, but the CEL and spark knock are gone and the truck accelerates well. I did notice a mild unburned-gasoline odor to the exhaust.
I work tomorrow, but will try to take it into a shop Friday morning to make sure the driver's-side plug wires are on tight, pull any pending codes, and perform a compression check on cyl#4 -- will update afterward. I leave for the holidays on Saturday, so I'll have to leave any other engine work until after the new year.

 

[Apollo-Soyuz 1975]

Well, cylinder #4 doesn't hold any pressure. Time for a rebuild.

 

[86 ranger]

i had this happin on my 86 ranger. it bent the valve and crack the head were the valve seat sits in the head.

 

[4b316]

that sucks big time

 

[Mark_88]

Well, the good news is you won't have to guess after the rebuild...

 

[auto117584]

mega bummer

 

[Apollo-Soyuz 1975]

I've flown down south visiting family at the moment, but I'll try to find a shop in Toledo that can look inside cyl#4 with a borescope to gauge the damage. I'm still hoping against hope that the damage is limited to the exhaust valve, valve seal, and/or head. Truck runs surprisingly decent on 3 cylinders (except for the shaking, lol)

86 ranger, did your motor have any scoring on the cylinder wall or piston top?

 

[Mark_88]

I had a crack in the top of #1 piston on my 2.0...drove it for almost 2 years like that...but the blow-by became too much when it started spitting all my oil out of every possible outlet...

Hope it is just the head...they're relatively easy to fix/replace...

 

[Apollo-Soyuz 1975]

Some good news after the holidays -- borescope inspection showed no damage to cylinder wall or piston! Truck will go under the knife on Monday - hopefully the machine shop will have the head ready to go in a couple days.

Thanks to all for the suggestions and kind words If I become a premium member I might have to appropriate Mark_88's user title... all this happened because of a loose spark plug.

 

[Mark_88]

Not a problem...about Einstien...lol

I recently had to correct a headlight wiring problem...in the process of that I somehow disconnected the power feed to my distributor...next day when I went to start the truck it would not fire...genius that I am, I sprayed quick start down the carb...still no spark...then I actually, I STG dumped gas down the carb thinking the fuel line was frozen (it was cold, eh)...then, after doing this, I remembered that I was frigging with the wiring the night before so I decided to inspect/disconnect/reconnect the wiring...

So, then I pulled out a plug to see if there was spark...as I'm sticking my head in the window to give it a crank...I no sooner turn the key when I hear this monstrous KABANG...

My new $40 muffler is now, how shall I say this...no longer new...

On top of this, I recently threw away an $80 muffler because I didn't think I would need it any more...

Where is that freaking head banging on the bricks icon when you need it...