The very most bizarre, happy engine breakdown

[mikepellegrini]

Or, how I re-learned the extreme value of properly torquing everything.

I went out to start my 83 NA this morning. Turned the key, BANG! from the engine compartment, the engine shuddered and I quickly turned it off, expecting the worst. Visions of engine overhauls danced in my head.

I opened the hood. A wisp of smoke came out of the fresh air breather - like from a backfire, I thought. No apparent problems. I thought I could smell fuel.

I stood and stared at it for a couple minutes. Then, figuring if it was the cam belt, the engine was already toast - so I said what the heck. I got back in and turned the key.

The car started right up, but ran just awful. Shuddering badly. and it was strange - it sounded like a major exhaust leak - almost like I was running the engine with the exhaust manifold off. I turned it off after 30 seconds.

Nothing made sense. Maybe the balance shaft belt broke?

I pulled the top belt cover off - the belts were both pristine.

The car was sitting in front of my house - so I got my youngest son, and we pushed it all the way around the block and into the garage.

Next, I put the car on top dead center - the marks lined up just fine.

Weirder and weirder.

So, logically, my next step was to check compression. Maybe the backfire had caused a catastrophic failure in one of the pistons?

Number one was fine - plug looked great. Number two, good, number three good. Compression all reasonably the same. Fantastic.

Finally, I get to plug 4. And therein, was my problem.

You see, there was no plug in number 4. None, nada, zip. It was lying inder the intake manifold - where it was blown out.

The loud BANG I heard was the plug getting spit out of the cylinder.

Apparently - 4 years ago - I didn't torque it well enough, and over the 4 years, it finally worked its way out - and when it was finally down to the last thread, it came out with a bang when I started the car this morning.

I checked the compression in number 4 - just great. The plug wasn't damaged, so I put it back in.

And the car runs just great again - like nothing happened. A very happy ending.

And that is how I re-learned just how very important it is to properly torque everything!

[running_cold924]

its a wonder your 97 ford expedition hasn't had this problem, lol. it happens to them a lot....especially the 5.4L 2 valves. sometimes the crazy things happen with these cars, you just never know what to expect. glad to hear is a "simple fix"

[John_AZ]

Originally Posted by mikepellegrini

[B] The plug wasn't damaged, so I put it back in.

Glad not other "damage" happened.

Thanks for sharing.

[cwiert]

so the plug fired up like a bullet and struck the underneath of your hood? that was the bang? I guess you're also lucky you didn't dent your hood from the inside.

[ernie9944]

Glad to hear it was just a minor problem ,when I had my 944 use to check the plugs on her every month or so don't take long "call it peace of mind"

[thewerxracing]

Wow.


Nothing worse than that feeling.



Nothing better than that feeling.



You can place those sentences accordingly.

[cvriv.charles]

Holy hell thats kind of funny. lol. 4 years on the same set of plugs?!?!? Drive it much? LOL. I didnt know a plug could work it's way out completely. lol. Truly funny.

[cwiert]

And just for the record, what IS the proper torque on the plugs?

[krystar]

a very light "yay much" officially prob like 5-10ftlb. so really finger tight, plus 1/4 turn or so

[944Spec_bound]

makes me think twice about leaning over my engine bay while the car's running.

Doctor: "Explain to me how you have a spark plug embedded in your armpit"

Patient: "Well, 4 years ago...."

[TSNAPCRACKLEPOP]

had a similar experience, riding a yamaha triple 750 with a sidecar. got about 75 miles from KC, headed south, in the dark and the rain, and pow!! made it back to kc on 2 cylinders.
nearly got killed that night.

when I pulled off into a construction area delineated by traffic cones to let accumulating traffic go on past me, , a small ricer car, speeding, hydroplaned thru the cones, missing the detour, and missed me by about 1 foot at high speed doing donuts thru the cones.

obviously, my mission is not yet complete.

[cvriv.charles]

Originally Posted by cwiert

And just for the record, what IS the proper torque on the plugs?

Till it dont turn no mo.

[djnolan]

15-18ft-lbs. The evener the plugs are torqued, the more even they will fire. This is due to the heat exchange between plug and the head. The resistance of the plugs changes with temp. Therefore spark is somewhat proportional to the temperature of the plug. And the more even they are torqued, the more even the spark and the smoother the engine will run.

[mikepellegrini]

I really was incredibly lucky. The plug appeared to have impacted the underside of the intake manifold - or something. The hood wasn't dented, and the plug was lying beneath the manifold.

I've since talked to a couple other people who had it happen, who, unlike me, were in way worse locations when it occurred.

The PO of the car changed the plugs when he bought it, so the plugs are probably closer to five years old (maybe 35-40,000 miles). They're 2 electrode platinum plugs (or whatever).

I've been thinking it was time to do something with them (because they're so old) but the car runs great and the plugs looked like they were maybe a few months old - so I'll probably just wait. You can't argue with success... (or put another way, "if it ain't broke, don't fix it...").

[djnolan]

Did it damage the plug wire when it ejected?

[porsche4life]

Originally Posted by cvriv.charles

Till it dont turn no mo.

An awesome way to strip the head right there... Hope you like heli-coils....

[AKCJ]

Yep. I know a guy who had a fairly new toyota pickup with a dent (bump?) in the hood from one of the plugs flying out.

Glad you didn't get damaged.

[mikepellegrini]

I was just really, really lucky.

I've looked closely at the hood and there's no mark at all.

I'm really sensitive to over-tightening plugs (don't like heli-coils all that much). Whe I do plugs, I just make them "tight" - and with this one exception, that's served me well...

[Tishabet]

Exact same thing happened to me! See here:
http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/474252-first-me-lost-spark-plug.html

[mikepellegrini]

Originally Posted by Tishabet

Exact same thing happened to me! See here:
http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/474252-first-me-lost-spark-plug.html

That sounds a lot more traumatic than the way mine happened - at highway speed.

I had no idea it was this common.