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centerchannel68 · Feb 6, 2007, 01:03 PM

This is the weirdest car story that's happened to me... well, almost... anwyay:

It's really cold here. The car didn't like starting, but I drove to school anyway. I was coming home for lunch, and whenever a car is cold, I keep the RPMs very low until it's warm, under 3k. So I was driving down the main street to come home, going about 30-35mph, rpms were about 2200 or so. Out of nowhere, there's this huge "BOOM' and the car starts shaking like crazy and making all these rattling/puffing noises. I pull into a gas station (there was one about 1/4 of a block in front of me), and I pull into a stall and pop the hood. Everything looks okay, except one spark plug wire isn't attached. Weird. So I bend over the engine, and peer down the spark plug tube. Nothing. Nada. Zilch. I can see the threads on the head where the sparkplug used to be. I call around, and I eventually decide to drive it 1.5 miles home, because if I screw up the engine, oh well, hodna engines are cheap, and I'd like to put in a newer more potent one anyway. I then get a ride with a friend and buy a magnet ona stick and 4 new plugs, and shove the magnet in the hole to see if I can find any chunks of metal... nope. Then I installed 4 new plugs. Funny thing is now I have a nice dent on the underside of my hood on the bracing from where the plug rocketed out of it's place and smashed into the hood.

Weird eh? Anybody ever heard of this? I put these plugs in myself, about 2 years ago... so they definitely were not installed incorrectly.

Sky Captain · Feb 6, 2007, 01:23 PM

Apparently the plug just unscrewed itsel out by vibration.
The engine is fine.
Replace the plug, tourque the plug a little tighter this time.

And yes, I have a VW do this several times.
I was afraid of over torqueing the plugs and stripping out the threads.
So they'd vibrate loose and POP POP POP.

TheWOAT · Feb 6, 2007, 01:25 PM

The threads were still intact???
Ive heard of Dodge and Ford V-8 engines blowing plugs, but that was due to lack of thread depth, and the threads would be obliterated.. Weird... maybe the plug got loose over time and just exploded out... I'd bet on an incorrect installation.

Gossamer · Feb 6, 2007, 01:32 PM

Originally Posted by TheWOAT

The threads were still intact???
Ive heard of Dodge and Ford V-8 engines blowing plugs, but that was due to lack of thread depth, and the threads would be obliterated.. Weird... maybe the plug got loose over time and just exploded out... I'd bet on an incorrect installation.

It's weird that an incorrect installation would take 2 full years to surface.

centerchannel68 · Feb 6, 2007, 01:45 PM

Originally Posted by TheWOAT

The threads were still intact???
Ive heard of Dodge and Ford V-8 engines blowing plugs, but that was due to lack of thread depth, and the threads would be obliterated.. Weird... maybe the plug got loose over time and just exploded out... I'd bet on an incorrect installation.

Dude, I've changed plugs dozens of times on hondas, dodges, subarus, fords, mercury's, caddys, geos, saturns, bla bla bla and there's never been a problem. I know how to screw in a freaking spark plug.

ChrisF · Feb 6, 2007, 02:18 PM

Originally Posted by centerchannel68

I then get a ride with a friend and buy a magnet ona stick and 4 new plugs, and shove the magnet in the hole to see if I can find any chunks of metal... nope.

Hondas have aluminum heads... not gonna pick up much of that with a magnet.

CMYKid · Feb 6, 2007, 02:22 PM

Originally Posted by centerchannel68

...so they definitely were not installed incorrectly.

no, of COURSE not.

centerchannel68 · Feb 6, 2007, 02:31 PM

Originally Posted by ChrisF

Hondas have aluminum heads... not gonna pick up much of that with a magnet.

Spark plugs aren't.

centerchannel68 · Feb 6, 2007, 02:31 PM

Originally Posted by CMYKid

no, of COURSE not.

Yeah, that's why this has happened in all my other cars, 2 years after I put in plugs.

Sky Captain · Feb 6, 2007, 02:47 PM

I've had a Cessna blow the top part of a plug out.
The plugs actually screw together so they can be remanufactured.

Millennium · Feb 6, 2007, 03:10 PM

Ouch. That happened to my wife once, and just as with your case the spark plugs had been working fine for years.

Not good, and sad to say, not cheap either.

CMYKid · Feb 6, 2007, 03:38 PM

Originally Posted by centerchannel68

Yeah, that's why this has happened in all my other cars, 2 years after I put in plugs.

which has nothing to do with anything. that IS why they call them mistakes. so its perfectly reasonable to assume that it'd happen on one and not on another.

regardless, its not THAT uncommon, properly installed or not. Repeated heating and cooling leads to repeated expansion and contraction, all the while subjected to vibration and internal pressure. Add extreme outside temperature (its not as if you live in FL) and the odds are good it'll happen sooner or later.

Replacements for Imports are certainly cheap though. For not much more than a used one you can get a virtually new engine since in a lot of countries you're taxed on your mileage once your engine passes a certain point. I put a replacement in one of my Supras that'd been pulled from somethingorother in Japan with under 40,000 on it. There are plenty of shops that specialize in only imported used engines.

Eynstyn · Feb 6, 2007, 03:48 PM

So are you going to build some new sparkplugs? Or find some perfectly good ones at the junk yard for a penny each?

smacintush · 04:30 PM

yeah, nevermind I had my brain in backwards…

zro · Feb 6, 2007, 04:14 PM

Bet it wouldn't happen to an SUV.

G4ME · Feb 6, 2007, 04:16 PM

Originally Posted by Eynstyn

So are you going to build some new sparkplugs? Or find some perfectly good ones at the junk yard for a penny each?

hell, i would just search the street for the one that blew, shes probably still good

nonhuman · Feb 6, 2007, 05:37 PM

Too bad it didn't go right through the hood. That would have made an awesome picture.

(Good thing for your wallet though...)

imitchellg5 · Feb 6, 2007, 05:45 PM

I've heard of that happening a few times, but with boats. My grandpa used to race hydroplanes, and he'd lose spark plugs sometimes at really high RPMs.

smacintush · Feb 6, 2007, 05:53 PM

Originally Posted by imitchellg5

I've heard of that happening a few times, but with boats. My grandpa used to race hydroplanes, and he'd lose spark plugs sometimes at really high RPMs.

I'm sure this is related to the thermal expansion differential between the aluminum head and the steel plug. I'm just not sure what role the cold weather might have played. I wonder if it got so cold that the Aluminum contracted so much that the thread were compressed a little so that when the car warmed up the threads were too loose. (does that make sense? Anyone?)

imitchellg5 · Feb 6, 2007, 05:54 PM

I'm picking up what you're putting down.

Gossamer · Feb 6, 2007, 06:03 PM

The thermal coefficient of expansion of aluminum is about twice that of iron. So if the heads were aluminum and plugs were iron, the fit would get tighter.

centerchannel68 · Feb 6, 2007, 07:58 PM

Originally Posted by CMYKid

which has nothing to do with anything. that IS why they call them mistakes. so its perfectly reasonable to assume that it'd happen on one and not on another.

regardless, its not THAT uncommon, properly installed or not. Repeated heating and cooling leads to repeated expansion and contraction, all the while subjected to vibration and internal pressure. Add extreme outside temperature (its not as if you live in FL) and the odds are good it'll happen sooner or later.

Replacements for Imports are certainly cheap though. For not much more than a used one you can get a virtually new engine since in a lot of countries you're taxed on your mileage once your engine passes a certain point. I put a replacement in one of my Supras that'd been pulled from somethingorother in Japan with under 40,000 on it. There are plenty of shops that specialize in only imported used engines.

Dude. I have a torque wrench. I installed the plugs to the suggested torque specs. They were gapped correctly, and installed according to the book. This was a freak occurance, which is why it was so weird. If I was some idiot who's never changed plugs before, then I could understand how it would be my fault, and an accident, but that's not what happened.

gargamel123 · Feb 6, 2007, 11:38 PM

I ran over a spark plug today with my bus. I finally got my bus running but it sure is cold outside.

Rob everyone makes mistakes you are not immune. On the issue of the spark plug, these things happen to a lot of people. Everyone just loves jumping all over you when something happens to you.