Stripped sparkplug thread

CraigD426 · March 14, 2009, 12:53:45 PM

Ok, so I was out for a ride today and a spark plug blew out!

I was motoring down I75 from Gainesville when suddenly I felt something hit my leg, alot of noise, hot air on my thigh and a loss of power. I looked down and saw my spark plug wire flopping around with the spark plug in it. Pulled over and it looked like it backed out, the belt cover was slightly melted where the plug wire passes through. Got the plug put back in and the bike fired up, so I went home very nervous it would happen again. My question is, has anyone ever had this happen to them? I'm about to go out and take the belt covers off to inspect everything now that the bike has cooled down some, any suggestions what I should be wary of?

V-twin · March 14, 2009, 01:10:00 PM

Never happened to me with any bike!! you only noticed it after it fall out?, thought you may have noticed a a lack of performance and a strange "chuff-chuff" sort of noise?

Well with that happening to you, good call to go over the bike and check all nut's/bolts and chips etc are all firm, was it serviced by recently?

herm · March 14, 2009, 01:38:18 PM

a good reminder to always do a complete walk around of the bike before riding.

CraigD426 · March 14, 2009, 01:40:53 PM

Yes, just had the 6,000 mile service done a few months back. When I got the covers off and the plug back out it looks like the plug had been cross threaded.

Now the only time that plug had been out prior to this was when the service was done, so I know it wasn't me. Prior to this the bike ran great, didn't notice any "chugging" which would indicate a loss of compression, just the sweet music of a Ducati DS1000

At any rate I'm going to call the shop where I had the service done on Monday to see what can be done.

rockaduc · March 14, 2009, 02:56:23 PM

I hope you get this straightened-out, but don't be too hopefull. You are essentially asking the shop to admit a mistake from several months back that just became apparent now.

I will keep my fingers crossed for you.

Popeye the Sailor · March 14, 2009, 03:04:24 PM

Quote from: herm on March 14, 2009, 01:38:18 PM
a good reminder to always do a complete walk around of the bike before riding.

Who on earth checks sparkplug tightness?
There is a limit.

needtorque · March 14, 2009, 03:06:36 PM

Should not be a problem. The shop would have to prove that he has removed the plugs since they did. The burden of proof will fall on them since he had the service done there and the plugs are the same as what they put in.

Don't let them helicoil it. It was their mistake and helicoils are a last resort to avoid buying a new head in my opinion. Since they made the error I would want a new cylinder head for free. This was no fault of yours so anything less than a bike in the same or better condition than what you dropped off to them is unacceptable.

CraigD426 · March 14, 2009, 03:18:56 PM

I hope it's not a hassle, the shop owner has always been good to me ever since I bought the bike.I'll keep updating when I know more.

herm · March 14, 2009, 03:26:01 PM

Quote from: MrIncredible on March 14, 2009, 03:04:24 PM
Who on earth checks sparkplug tightness?
There is a limit.

yeah, the limit is whatever you make of it.
a quick tug on the plug caps may well have prevented this during a walk around.
YRMV

needtorque · March 14, 2009, 04:09:14 PM

Quote from: herm on March 14, 2009, 03:26:01 PM
yeah, the limit is whatever you make of it.
a quick tug on the plug caps may well have prevented this during a walk around.
YRMV

I doubt it though. It was likely tight before the ride. He made it some distance after all before it came out and the pressure from the cylinder pushing out on the plug would have ridiculously higher than tugging on the wire. If it was loose enough to feel with a wire tug before the ride the chance of it going even a mile would have been slim to none. Once the threads are compromised, especially on aluminum, it is just a matter of time before they let go. I have seen many Ford V8 engines blow factory plugs out, threads and all, at varying miles. There is no way to tell when it will happen.

Old-Duckman · March 14, 2009, 04:44:44 PM

I'd be willing to bet that they will not try to blame you. But...I'd also be willg to bet that they will deny your request for a new head.

I also would not want a Heli-Coil but a TimeSert is a very nice repair for a stripped out spark plug hole. If they suggest Heli-Coil, I'd request a TimeSert.

I hope you get a new head out of the deal...but I'd be suprised.

Keep us informed.

DuciD03 · March 14, 2009, 04:52:12 PM

Quote from: needtorque on March 14, 2009, 03:06:36 PM
The shop would have to prove that he has removed the plugs since they did. The burden of proof will fall on them since he had the service done there and the plugs are the same as what they put in.

Don't let them helicoil it. It was their mistake and helicoils are a last resort to avoid buying a new head in my opinion. Since they made the error I would want a new cylinder head for free. This was no fault of yours so anything less than a bike in the same or better condition than what you dropped off to them is unacceptable.

1+ above; couldnt have written it better; post back on the outcome; one other thing; I'd carefully check the other plugs before they touch it; plugs should all move easily in and out in the head threads; and snug to the proper torque (1/4 turn max). The must have cross threaded or over torqued stripping the threads out of the head ... there aluminum heads so the threads are delicate. Expensive & a Boan head move but mistakes do happen

Also could you add "stripped sparkplug thread" to your title? This is the first time I'v heard of this ... but evidentlly it happens on occasion ...

Porsche Monkey · March 14, 2009, 05:29:24 PM

In my professional opinion it sounds like the plug wasn't torqued correctly. That means with a torque wrench. This is very important because of the different thermal expansion rates between an aluminum head and a steel spark plug. Also do NOT use anti seize on an aluminum head for the same reason. The dealership screwed up. I am suprised that you didn't notice any odd sounds but then again wind noise may have covered it up. Not likely that they will replace the head unless the bike is still under factory warranty. A properly installed time sert will be stronger than factory and this is a viable option but still requires head removal. Good luck.
Jon

CraigD426 · March 14, 2009, 05:29:35 PM

QuoteAlso could you add "stripped sparkplug thread" to your title?

Done

I talked to a friend of mine who is big into Ducs and he also suggested the Time-serts, I'll see what the shop says. Heck if they take off the head and put a time-sert in at no charge, I'll be ok with that. I looked into time-serts and they seem pretty heavy duty, but this is something best left to the shop, not cause I'm nervous about doing it (I am), but the way I see it, it's on them.

Oh, and the plug wire that this happened on is the one that goes through the belt cover on the top cylinder, seeing as how the rubber boot seats into the plastic of the belt cover I doubt I would have noticed it being loose if I had wiggled it.

Langanobob · March 14, 2009, 06:50:26 PM

Hope the shop cooperates and puts on a new head. Screw-ups happen even at the best shops and I hope this is an isolated incident - but...If they are going to install a Time-sert I'd be concerned about letting a guy or a shop that can't properly thread or torque a sparkplug do this kind of repair. It seems to me that you should be able to request that a qualified machine shop do the actual thread repair work.

Good luck and keep us posted.

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Stripped sparkplug thread