Stripped spark plug

JimS · Mar 28, 2015

My girl friend's Isuzu Rodeo blew the number one plug out and stripped the thread. No idea why this would happen after the plug having been in so long.

What are the best repair solutions without pulling the head?

Thanks

notjustair · Mar 28, 2015

Helicoil. Google it. It shouldn't be a big deal as long as you don't have to do stupid pet tricks to get to the hole to put it in.

jeffcat · Mar 29, 2015

Or a mechanic who knows what he is doing. WAY cheaper than a new head!

ASEguy · Mar 29, 2015

There are inserts made for such a repair. A lot of inserts have been put in Ford's 5.4. If you are comfortable doing a Helicoil, don't leave metal shavings in the cylinder.

JF in MI · Mar 29, 2015

Have seen that plenty of times when I was "in the business". Crank the engine by hand until the intake valve, on that cylinder, is open. Run air pressure into the PCV hose so air is steadily blowing out the spark plug hole. Wear a face shield while cutting the threads for a helicoil. All the chips should blow out while cutting and break the helicoil tip off with some locking pliers.

JimS · Mar 29, 2015

PVC air hose is a great idea. That's why I post here. Thanks.

ObsoElitist · Mar 29, 2015

KD inserts and Timeserts are superior to Helicoils because they are a solid piece with a stopper flange, rather than a coil of wire that allows carbon, fluids, and corrosion to leak through. Always use a dab of anti sieze on plugs to prevent the problem.

jimg.allentown · Mar 29, 2015

Cannot use Heli-coil for spark plugs. They do not seal pressure, and will leak combustion gases which will over time erode the material away. The only reasonable way to repair is by tapping oversize for an insert, and using epoxy to secure the insert.

jimg.allentown · Mar 29, 2015

The only good way to repair this is with an insert. There are many on the market. I have used some from Auto Zone with some success. There is also a really high quality repair kit available from Cal-Van tools that does a first class repair. It is a bit pricey, but in the long run it will be a permanent fix. As far as doing the tapping, I have found that in the absence of available air pressure, you can use wheel bearing grease to capture the chips. Put the grease on the tap, cut about 1 to 1-1/2 threads, and take the tap out and clean and re-grease it. Take another turn or so, and keep repeating. Keeps the chips out of the cylinder, but it is tedious and takes time. BUT.....time is cheaper than a $100/hour shop.

ObsoElitist · Mar 29, 2015

I was taught on VWs to open the exhaust valve, grease the tap, and blow any remainIng chips out the exhaust port. Not sure if thats a good idea with a catalytic converter equipped engine.

Owen Aaland · Mar 29, 2015

The Heli-coil inserts for spark plugs are not a wire coil like the other Heli-coil thread inserts. They are a solid piece like the other brands.

mkirsch · Mar 30, 2015

As to WHY it happened, which is what you asked...

Likely the threads have been stripped for some time now. Someone overtightened the plug during the last change.

Stripped spark plug

JimS

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notjustair

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jeffcat

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ASEguy

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JF in MI

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JimS

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ObsoElitist

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jimg.allentown

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jimg.allentown

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ObsoElitist

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Owen Aaland

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mkirsch

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