$300 for a stripped spark plug housing thread repair?

[Gaffey Cat]

Hi everybody. I work with a Husqvarna 372 XP that had its spark plug housing thread stripped (...from my own carelessness). From every other forum posts I've looked at, it seems like a straightforward fix: buy a thread insert kit ($40-50), and maybe take it to a shop to have a professional install it.

However, my company is telling me it's a $300 fix. They haven't taken a close look at the saw yet, but can anyone tell me if it actually comes out to that much for a thread replacement? Is there anything I haven't considered?

Thanks

 

[Landmark]

Welcome to AS. This thread might help you.
http://www.arboristsite.com/community/threads/stripped-spark-plug-repair-ms361.272088/#post-5189799

 

[Gaffey Cat]

Welcome to AS. This thread might help you.
http://www.arboristsite.com/community/threads/stripped-spark-plug-repair-ms361.272088/#post-5189799

Thanks, I'll definitely look that over.
I'm mostly wondering about cost, though. Here's my take on it: I'm definitely going to need the new thread insert kit (say $55). If the shavings from my old thread have fallen into the cylinder, then I'll have to replace that too (it looks like $40-120 online for a new piston kit). So, to me, this doesn't look like a $300 fix, but I'm just hoping knowledgeable people here can confirm or disprove it and I can go from there.

 

[Four Paws]

You can buy a new cylinder for much less than $300.

You can make the repair yourself if you purchase a kit.

 

[Onan18]

For it to be a $300.00 fix they must be talking piston and cylinder. Buy the inserts that have the teeth in them, install with red loctite and let sit overnight. Also remove the cylinder before tapping, creates an amazing amount of metal shavings.

Joe

 

[treesmith]

Did this on a 390xp, someone had put a new spark plug in finger tight then ran it till it stopped running.

Pretty simple - Stripped the saw down, removed cylinder, drill and tap hole, put in helicoil with loctite studlock, put back together, done. still going strong 6 months later and it gets worked hard.

If you don't fancy doing the helicoil bit, you can at least save some money by stripping it and assembling yourself, $300US sounds pretty steep for a straightforward job

 

[Pud]

Dunno what the hourly workshop rate is in the us but where i live its $98 an hour , 3 hours to get the saw clean enuff to work on remove head muffler carb fit insert few new gaskets refit everything and give it a quick test in a log seems pretty fair to me

 

[Big_Wood]

Did this on a 390xp, someone had put a new spark plug in finger tight then ran it till it stopped running.

Pretty simple - Stripped the saw down, removed cylinder, drill and tap hole, put in helicoil with loctite studlock, put back together, done. still going strong 6 months later and it gets worked hard.

If you don't fancy doing the helicoil bit, you can at least save some money by stripping it and assembling yourself, $300US sounds pretty steep for a straightforward job

the timesert kits come with a single tool which is a chaser and a tap all in one. the chaser pulls the tap through cutting new threads, no drilling even needed. not sure if the heli coil ones do or not now. i got dig that stuff out here, got an 066 redlight to do.

 

[Chainsaw Jim]

That cost sounds about right for a busy mainstream shop. A mom and pop shop might knock a good $100 off.
Onan18 hit the nail on the head up above. To be done properly it is a complete tear down.

 

[Homelite410]

That cost sounds about right for a busy mainstream shop. A mom and pop shop might knock a good $100 off.
Onan18 hit the nail on the head up above. To be done properly it is a complete tear down.

Well not complete, just take the jug off. Its only 8 bolts.

 

[Chainsaw Jim]

Well not complete, just take the jug off. Its only 8 bolts.

You mean 4 bolts, and on a brand new saw. Parts will start stacking up next to you on the bench pretty quick when you realize how much needs cleaned up before you can put it back together.

 

[Homelite410]

2 muffler, 2 carb, 4 jug bolts. Easier to pull if you remove top handle as well.

 

[Onan18]

No, you have the three for the top cover, two for the muffler support (plus another two if you decide to remove the muffler, not necessary but makes it easier) at a minimum one on the wrap handle for the AV mount (personally I remove the wrap handle for more room, so four more) pop the tabs for the carb mount, then the four cylinder screws. So any where from 10 to 16 depending on how much you want to wrestle with it.

Joe

 

[Nitroman]

Dunno what the hourly workshop rate is in the us but where i live its $98 an hour , 3 hours to get the saw clean enuff to work on remove head muffler carb fit insert few new gaskets refit everything and give it a quick test in a log seems pretty fair to me

That's funny right there!

 

[Milkman31]

At $300 I could pay some stuff off in a hurry if I could do them all day long. Even if they were mini Macs or the homelite 330 lol!!!!

 

[Rx7man]

If someone knows what they're doing I don't see more than 1 hour to re and re the jug... 20 minutes cleaning, a half hour to drill and tap. Check ring clearance while you're at it. $40 for new OEM rings if it needs it.

The other option which you can do yourself is get a new jug, piston and rings for $100 and put them on yourself. take your time and fix the jug when you find a cheaper solution.

 

[Foragefarmer]

Is the company you work for expecting you to pay for the repair?

 

[Derf]

I'd bet dollars to doughnuts the company is likely NOT considering a threaded insert. For $300 they are charging you for dismantling and replacing the entire cylinder.

A threaded insert could likely fix your problem for much less. But keep in mind that the amount of material to grab the insert is only about 1/4" thick.

Make sure to order an insert that is one size larger but also thin enough to not hit the piston at TDC. I'd rather be drilling it out in a press, but the angle of the spark plug necessitates probably just going at it with a hand drill. Not ideal, but doable if you're careful.

Also, I know inserts are great replacements on stripped threads, and have used them in all kinds of applications from stripped oil drain plugs to you name it, but never a spark plug hole where you're dealing with high temperatures, high pressures, and dissimilar metals (insert is usually steel, cylinder is aluminum). Which means that although it will "likely work fine" since others have done it with success, that isn't a guarantee that the repair will last. Which brings me back to my first point that the company likely doesn't want to mess with an insert and is suggesting a new cylinder.

 

[Rx7man]

If they're charging for a new cylinder I'd take a gamble and helicoil it without removing the cylinder. do it with the piston near TDC and blow it out thoroughly, perhaps wash it with fuel/solvent too.. the metal you're drilling is aluminum which is way softer than either the nikasil or the piston rings.. in all likelyhood it'll be just fine, and it'll be really cheap to do. I do admit it's a bojang way of doing it, but at the price they're charging I'd gamble on it.

 

[Onan18]

OR undo the four snaps that hold the airbox cover on and remove it, remove the plug wire and air filter, remove the three screws that hold on the top cover, the two muffler support screws (plus the two muffler bolts if you decide to remove it, not necessary but makes it easier) the one screw on the wrap handle for the AV mount (personally I remove the wrap handle for more room, so four more) pop the tabs for the carb mount, disconnect the throttle cable and fuel and impulse lines then remove the four cylinder screws and off comes the jug. With abar wrench, a good 4 & 5 mm T Handles and a pair of hemostats it takes about 20 minutes to have it apart.

Joe