Spark plug stipped, BIG problem

[jack202]

I have a 64 mercury 650 and I noticed the top spark plug was loose, tried tightning it and found out it was stripped. The previous owner had already helicoiled it, but that helicoil striped out of the alluminum, so the hole is now huge and i can't just use another insert. What are the ways to fix this, I talked to a boat guy earlier and he said they used to use something called a keensert was was a larger diamiter plug. Does anyone know about this?? And could anyone point me in the direction of finding it??<br /><br />John

 

[Laddies]

Re: Spark plug stipped, BIG problem

Mercury Marine use to sell dealers the keensert kit

 

[Trent]

Re: Spark plug stipped, BIG problem

web page

 

[Clams Canino]

Re: Spark plug stipped, BIG problem

If that does not work....... you could have an aluminum insert made/machined that would screw into the hole, then screw the plug into it.<br /><br />-W

 

[JB]

Re: Spark plug stipped, BIG problem

I recommend replacing the head, Jack.<br /><br />Here is why: Spark plug "heat" is dependent on the rate at which heat is conducted from the electrodes to the block. If the material that the plug is screwed into changes the rate of conduction changes and that plug will either run hotter or cooler than the engine designers intended. That spells changed performance and altered engine life.<br /><br />You should be able to pick up a used head from Twin City Outboard at a reasonable price.<br /><br />Good luck.

 

[Zamboni]

Re: Spark plug stipped, BIG problem

Suprised you can't just thread a new helicoil in, normally when they thread out that works-strange the hole "is now huge"<br /><br />Keenserts are avilable from few manufacturers, some are garbage. Find local engine rebuild shop dealing with Holcomb/Lawson/premier and buy $2 insert from them, they should lend you the size specific install tool for knocking down the keys...if you need to buy insert tool, odd size drill bit and tap it might be cheaper to have them install the Keensert.<br /><br />What JB says makes sense, I've only installed these on exhaust side of locomotive diesel engines.

 

[jack202]

Re: Spark plug stipped, BIG problem

Originally posted by Laddies:<br /> Mercury Marine use to sell dealers the keensert kit

That's what i've been told, but i've also been told by a few keensert dealers that they are no longer being made, what are the chances of finding a shop somewhere that has a few laying around...I really don't want to rip the power head down and have the hole welded shut and retaped.

 

[jack202]

Re: Spark plug stipped, BIG problem

well the spark plug is m14x1.25 like i said it was drilled out for hellicoil by previous owner, and now that has pulled out stripping out the alluminum again. So i just need something larger I'm goint to check out the time-cert and see if this will help

 

[Chinewalker]

Re: Spark plug stipped, BIG problem

JB - the head is cast into the motor block on that engine - and pretty much all old-school Merc inlines...<br /><br />- Scott

 

[JB]

Re: Spark plug stipped, BIG problem

OOPs! MY bad. Thanks, Scott.<br /><br />In that case I would go to a Time-sert. The only source I know of is clarks@corvair.com but you may be able to find them elsewhere.<br /><br />The Time-sert has outer threads that are "timed" to the inner threads to produce uniform, thin inserts. They will give you the closest to stock heat transfer of the options I know of.

 

[Zamboni]

Re: Spark plug stipped, BIG problem

What size do you need Jack202, length also...for example the M12x 1.25 comes 1/2 and 3/4.There "high-strength aluminum alloy" so problem JB pointed out doesn't apply....contact only has M12's and M14's spark plug sizes.

 

[Zamboni]

Re: Spark plug stipped, BIG problem

I have a 2 year old Lawson catalogue with exactly what you need, checked and these metric aluminum keyserts aren't on their website now so no longer carried. Might be available elsewhere, if you want me to email a scan of catalogue page post your addy. <br />What length do you need,M14 x 1.25 come 3/8,7/16,1/2,3/4...I don't mind asking tomorrow if any old stock available.

 

[DHPMARINE]

Re: Spark plug stipped, BIG problem

K-D Tool used to make a different insert,that had a flange on it .<br /><br />DHP

 

[gss036]

Re: Spark plug stipped, BIG problem

http://www.timesert.com/ <br />Newest web link for timesert, maybe you can someone close by that carries them.

 

[Zamboni]

Re: Spark plug stipped, BIG problem

Timeserts looks good, the keysert would be preferable because its aluminum/alloy...ad says spark plug will operate at normal temp.

 

[jack202]

Re: Spark plug stipped, BIG problem

well i spent an hour on the phone with Bill from timesert, he says that my hole is out of spec for his insert, off the record he said it will probably work but there was no garentees. So I went ahead and ordered the kit and inserts directly from timesert (as i know i would get them asap since they would have them in stalk) The kit number is 5141 and the inserts were 51401 for future reference.