Zero10

Hello again,
I have run into a rather unusual problem today. I had been driving the car pretty hard, since the break-in miles are over, and the weather is nice here and there, I was getting on it pretty hard for most of the day, and after picking up my G/F's friend, and taking her home, I went to get out of the car, to get something from the hatch, and my car sounded like it was running on 3 cylinders, but it had a really nasty backfire instead of the 4th cylinder. Since it was only 2 blocks round-trip to grab my G/F, I picked her up, then pulled over to check my spark plugs, I presumed that my #4 plug had fouled-shut, since it was foulding badly, due to my oil burning problem. In the 2-block round trip, it went from idling funny, to barely running, I could no longer drive above 30kph, or over 3000RPM in first gear, so I coax it back to the garage, and pull my #4 plug.

The entire center piece was loose, the center electrode, and it's entire ceramic housing was just loose. Upon closer inspection, it had blown oil and soot all over the top of my engine, and it appears that it blew the spark plug wire half-way off. I have never seen a spark plug do this before. I re-installed one of my old plugs, to get around for tonight, until I can get a new plug tomorrow (a beru ultra). I run Bosch coppers (WR7DC), and have never had a problem before.

The entire center piece spins freely in your hand, and moves in/out about 1/4".

Is this just a defective plug, or is this something I have somehow done to it? (I would hate to have another plug fail like this, I don't always carry a full toolkit in my car)

bearone

defective unless you overtorqed it and that's a quick way to damage the threads in the head.

87951

Zero10

Nope, I'm super-**** about everything. I use a torque wrench on my spark plugs, and they are indeed torqued to spec. Just curious, but how would that affect the inner part of it anyways? I couldn't think of anything I've done to break it like that, but it just seems so odd to have that happen.

NZ951

Zero, what do you torque your plugs to?

special tool

Number 4, huh? Does the car lose coolant?

Charlotte944

The only time I've seen this is when a head gasket blew. The failure was at #3 cylinder. As the piston came up on the compression stroke, the higher pressure blew the mechanical seal on #3 plug.

Zero10

Hmm, I wonder if it had anything to do with how much oil it is burning... If you rev it up (i.e. 5000rpm+), then shut it down right away, and pull the #4 plug, you can see a decent sized pool of oil in the cylinder. That might explain the wacky noise at startup as well....
I better get moving on my replacement engine.

Lately, when I fire it up, it will turn over almost once, then I kind of hear a knock/clank, and it will almost stop turning over for half a second, then it will turn over once more, and fire right up. Figured it was my starter taking a crap on me, but if I was getting one cylinder full of oil, that might do it too.....

Head gasket is good, not losing any coolant there. I have lost ~0.5L over 3000 miles, and I can see where it's leaking, it's just tough to get to, so I haven't fixed it yet.

If I installed a ring upside-down, could I scrape this much oil into one cylinder?

For spark-plug torque, I can't recall off the top of my head, but I think it was 25lb/ft.

dand86951

Zero I would first just rplace the plug after doing a compression check and see if it was the plug. I have had the ceramic break on a Bosch plug which I don't think was due to incorrect install. Re the oil do your other cylinders look ok? Did you have the head rebuilt with new guide seals. Perhaps one guide is loose and maybe the seal isn't sticking on the valve guide letting oil in. Do you notice a cloud of blue smoke on start up?

smokey

Plugs can be defective. I once had a plug blow out its centre completely in an Alfa Romeo, and the engine would whistle. The plug put a dent in the hood when it blew out. More recently, I had exactly the same symptoms you described on a newly rebuilt 951 engine, and it was a defective plug. The unburned fuel plugged the cat, and it took me a while to figure out why I was way down on power at the track. Had to install a new cat, so it was an expensive defect. It may also have washed the cylinder walls with gas. My mechanic installed a new plug, and the problem never recurred.

Zero10

I think the machine shop made a mistake on my #4 cylinder, it burns oil like CRAZY. It will foul a new plug in under 50 miles, to the point where it will barely fire. I am cleaning that plug every day or two, and going through about $40-$50 of oil a week. Almost as much as I spend on gas... It's funny, I can swap the plugs around, and if I put that plug in any other cylinder, after 100 miles, it's perfectly clean again, so I rotate my spark plugs to keep them clean, lol.

Head was rebuilt, new guides and seals, block was bored, new pistons, new rings, all new bearings, full bottom-up rebuild. I don't know why it burns oil so bad. But I'm working on building up a spare short-block, and swapping everything over, so I can tear this one down and find out. Just don't have the funds, after dropping $4500 on this last rebuild, I can't afford much more than $1000 on this new one, lol.

That's the story on the oil burning. I got my new plug(s) today, and the guy at NAPA swore up and down that it had to have been a defective plug, and that I would snap rods before I would blow the center out of the plug if it had been too much oil in the cylinder. Who knows if he was right...?
As for the torque, I had the number right, but the units wrong, it's 25Nm, not lb/ft, I was tired when I posted last.