stripped spark plug threads

[tcman]

Unfortunately I was replacing my spark plug and stripped the threads. Anybody ever use a spark plug thread chaser before? I heard that I should use a lot of grease to catch any metal shavings from falling in the engine.

Any advice would be helpful....I don't want to bring it in to the shop if possible.

Thanks in advance.

[brav01]

Thread Repair

If that doesn't work you can use a "Helicoil" thread repair system. These are available at Grainger and other hardware shops.

[Jonsboat]

I use one any time I have a plug I can't screw in using my fingers just to keep the threads in good shape. I put the piston at TC compression and blow air in the spark plug hole after I'm done to get the debris out of the cyl. Has been working for 40yrs. If threads are too stripped to work go the heli coil route.

[Myers]

If you get concerned you might not have the "crumbs" out of the cylinder, should any get in. Take a powerful shop vac, make a tube to fit the hole tight, suck out what you can. If still unsure, clean shop vac so you could eat out of it, shoot a bit of WD40 in the hole, then do it again. Empty shop vac, examine particals and see what you got.

[alaskamokaiman]

Put a nylon sock over the vac hose you will see what you got.

[Alaskan Fly Guy]

How about magnets? or are we talking about aluminum?

[tcman]

How about magnets? or are we talking about aluminum?

Yeah, it's aluminum.

[fishin_ak]

Helicoil

If the threads are actually stripped, I would advise the helicoil. A chaser is only designed to remove small burrs like Jonsboat alluded to with a plug that's a little hard to thread in. If you've never installed a helicoil before I'd recommend a machine shop do it for you. It shouldn't cost you too much and you'll have new threads instead of trying to get the plug to catch in what little aluminum may be left. Just my 2 cents.

[SusitnaAk]

We did this one time on i think was volo penta swedish outboard it was a 40 hp, they didn,t have removeable heads,had to change whole block,All the above on the advice, with the vac i would put right in there while you are drilling out the hole, go slow and straight!!! keep bring the bit up to keep the shavings come up,What engine is it?? How much room does have up there?? Because it is scary how big a hole you have to make for this!!!Keep and eye on it Maybe locktight the coil We didn,t and it didn,t last the summer.It kept vibrating loose, until finnally blew out. Myself i would call this a patch. I would change the head

[fishin_ak]

If a helicoil is installed correctly, it will be just as good as the original hole. Better actuall because the helicoil is made of spring steel, not aluminum. You are correct, the size of the hole will be daunting if you've not done it before. Loctite is a must. Just my two cents again but you're talking about your boat, not an ice auger or lawn mower here. I'd call around, find our who will install a helicoil for you and let them do it. I personally se no reason why you would replace the head. You might be doing that however with a do it yourself job. I'm a helicopter mechanic by profession but if it came the the aluminum head on my boat, I'd let someone else do it. Again, just my 2 cents.

[fishin_ak]

maybe if i keep giving you my 2 cents you'll be able to pay for the repair.

[Alasgun]

Bad plug thread

Having been a machinist for over 35+ years, I'd recomend refraining from anything "Hand" related. Unless your one of those win the lottery types, you'll soon discover how BAD your luck can be.

However all is not lost as I will do the work for you for free, if your willing to do it in my time frame. I work on the slope and am only there half the time. We only need to get it apart enough to get it in the bridgeport and yes I have the afore mentioned air compressor and vaccum.

If your interested P.M me for the particulars.
Mike