Spark plug blew out

[esblow]

I have never heard of such a thing until it happened to me, but my spark plug blew right out of the cylinder head while I was idling at a stop light. At first I thought maybe it rattled loose like a lot of the other parts are prone to doing, but no such luck. When I screwed it back in by hand it just kept spinning and spinning and spinning.

I will admit that I tried a rash roadside repair. I put a few layers of teflon tape on as tight as I could and it felt good and tight when I screwed it back in. Of course it didnt work so dont bother trying if you ever find yourself in this situation. I tried it for you. It failed.

So, does anyone know of a way to fix this or have a spare head lying around for an LF200GY-5?

Thanks in advance,
Eric

[IronFist]

I've never heard of such a thing on any bike, ever. Waiting on what others say. 8O

[TeamCheap]

Are you saying the spark plug threads are stripped in the head?

If so there is a repair for that but I have never had to to it but once done you should be fine.

EXAMPLE-Plug repair inserts

[warrior91]

Heli coil makes spark plug thread repair coils...available at most fine welding shops.

[IronFist]

That's exactly why I hang around. Now I know.

[esblow]

Yes, when the plug blow out it stripped the threads in the head. I found lots of Sav-A-Thread kits around the auto parts stores here, but they are all for 14mm plugs. I need the 12mm kit (M12x1.25 to be exact)and they are around $75 if I order it from Napa. Is this my only hope for a repair???

[winwun]

I did a fix on an old B & S engine some years ago, and I don't know if it will work for you, but what I did was:

1. Bought a plumbing bushing with the inside threads SMALLER than the spark plug I wanted to use and with the outside threads LARGER than the stripped hole in the head.

2. Took a tap with the SAME threads as the spark plug I wanted to use, and threaded the INSIDE of the bushing, and tested the plug to make sure it would thread in good.

3. Took an NPT tap with the threads the SAME as the OUTSIDE threads of the bushing, and threaded the stripped-out hole in the head.

4. Mixed up a little dab of JB Weld and smeared it on the OUTSIDE threads of the bushing, hit the JB Weld with a hair dryer for a few seconds to get it good and runny, and then screwed the bushing tightly into the head and let it sit overnight.

5. Insert spark plug into the bushing, hook up the plug wire and go riding . . .

[katoranger]

The thread repair kit or winwun suggestion is your best bet.

Google ford 5.4L triton v8 sparkplug. Lots of examples. Notice in TC's link that is says "approved by Ford Motor Company"

Allen

[TeamCheap]

And that link was about the first one I liked that came up in my quick search.

If I were to do that repair I'd want to make sure there is no way it could loosen up and end up lower and into the piston 8O .

If you do the repair could you post pics of the process for others to learn by as I can see that happening to others easily enough.

[VinceDrake]

Originally Posted by katoranger

The thread repair kit or winwun suggestion is your best bet.

Google ford 5.4L triton v8 sparkplug. Lots of examples. Notice in TC's link that is says "approved by Ford Motor Company"

Allen

Lots and Lots of examples! Did one today, doing another Tuesday.

Just as a side note, The Heli-coil kits work very well, and I would consider tem to be a permanent repair. *However!* I would strongly, strongly recommend to anyone doing this kind of repair-- Red Loc-tite the thread insert to the cylendar head! Then after it sets up, insert te sparkling plug.

It really makes life a pain in the sphincter when the insert unthreads itself with the plug, and then you throw the plug out.... Trust me. I find Just bending the tang on the thread, as Heli-coil suggests isn't as effective as a little bit of Loc-Tite.

Also, Heli's being made of a decent steel, are better threads than the original aluminum head's were.

--Vince

[knothead]

Time-serts are better than helicoils... at least I think they are. I've used both and it seems the time-serts hold up much better as they cannot back out once installed, they have a lip to keep them from screwing in too far and the bottom expands into the hole to keep it from backing out. Plus they don't use loc-tite to secure them in the hole, which is a good thing as loc-tite will sometimes loose it's grip when it gets hot.

Either one requires that you re-tap the hole first. When doing a spark plug hole with the head on the engine, coat the tap with a thick layer of grease to catch all the chips.

Check with Autozone (if you're in the US) about tool rentals, if they have the tap for rent you pay for it up front and get all your money back when you return the tool... that would leave you spending money only on the insert.

[winwun]

Knothead, what a great idea, coating the tap with grease to catch the chips . . .

I am 76 years old, and that never occured to me -- thanks for the tip.

One other potential problem about the repair, no matter how you do it, is the possibility of electrolytic reaction between two dissimilar metals.

In most cases, unless a neutralizing agent is used (and even IT can cause problems), you will get corrosion between the two different metals, and the corrosion will eat into one or both metals, causing the threads to loosen.

The corrosion is not an immediate problem, and may not show up, even in a few years, but the danger is present.

I patched up the holes left on the front of an aluminum boat when the running lights were removed, the patches being of thin (32 ga) stainless, and about 4 X 6 inches, held on the boat with aluminum pop-rivets.

About a year later, I noticed corrosion around the edges of the patch, the corrosion looking like that often found on battery cables, and on a hunch, I took a voltmeter, and on the 6v DC scale, I measured .4 VDC between the patch and the boat.

[BUG]

Just a stab in the dark here but maybe the 12mm kit is hard to find because you could just retap the head to accept a 14mm plug.

Originally Posted by esblow

Yes, when the plug blow out it stripped the threads in the head. I found lots of Sav-A-Thread kits around the auto parts stores here, but they are all for 14mm plugs. I need the 12mm kit (M12x1.25 to be exact)and they are around $75 if I order it from Napa. Is this my only hope for a repair???

[warrior91]

Grease may hold chips fine...but in the trade you find that chips are the main cause of wrecking a fine tap job.
The chips tend to get caught between tap cutting teeth and rip/wreck the remaining threads...or wreck the start as you try and back it out...
Personally IMHO digging into a head would be better with head removed off the block on a solid table in good light next to an airhose/solvent tank so you can wash foriegn material off and visually inspect head before reinstalation....
I have visions of a poor tap job, followed by a blob of grease/chips hanging above the piston...ready for the first revolution to spread and deposit filings throughout internals...
:roll: -quicky spark plug job could cause massive chinese heart attack -
I am pretty sure you could remove head and reuse gasket if you are carefull...all autoparts stores sell material you could cut yourself if you do wreck it...saves tracking down/waiting for "OEM" gaskets.

[ejcycles]

Knothead's idea works very good if you are very careful. I have done the same many many times. The trick is to almost completely fill the grooves of the tap with a tacky axle bearing grease, I use Amsoil red axle bearing grease. Carefully start the tap, once you get it started twist it a few turns to get the threads started. Remove the tap and clean it, re-apply grease and do the same until you are all the way through. With the piston a TDC take a rag and a very thin screw driver, wrap the rag around the screw driver and soak the rag with brake cleaner. Put the rag & screw driver into the threaded area to remove any extra chips and grease. Do this a couple of times till the hole is clean. Then install your insert.