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Cross Threaded Spark Plug Hole

Plattsy

By Plattsy,
in General Maintenance

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Plattsy Grand Master

Plattsy

Posted
Posted

Whats the best fix gents, geezer I know has a cross threaded spark plug which may be causing a miss fire, it's on the 6th cylinder so it's a pain int the arse to get too, but can this be tapped or re plugged?

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Plattsy Grand Master

Plattsy

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Posted

Just do what you did in europe then

tools are in Europe hence why he need's somewhere who can do it.............. and a generator is a little different to a skyline engine. if you feck the gen up nobody cares, i break his skyline he will cry!

anyone ever had it done by a mech?

to be honest even if i could borrow the tools i wouldn't feel confident.... we used to fill the hole with a rag forced into the top of the cylinder with the piston at tdc, once it was tapped we would vacuum out, remove the rag, vacuum again, then use a tiny fiber optic camera with a light to look for the fillings. it used to work. anyone confident enough to do this around the peninsula?

scotty nm35 Grand Master

scotty nm35

Posted
Posted

If you grease up the tap it should hold most of the chips in the flute, I'm guessing the thread only needs a cleanup anyway, as if the plug were fully cross threaded it would need to be removed and helicoiled.

A vacuum cleaner with a length of hose attached sounds like the go for cleaning out the bore, and those snake cameras are only $100 these days.

I doubt that is the cause of the missfire though...

533 RYC Proficient

533 RYC

Posted
Posted

Ok, heres the best & EASIEST way to do it WITHOUT getting anything in the cylinder. I work in heavy engineering, & am an engineer. Showed an apprentice this trick yesterday after he f**ked an oil gallery plug hole on an installed crankshaft. (7,042 c.i. V12). Compressed air is required.

1. Bar engine over till intake valves for cylinder are open, exhaust valves closed.

2. Find a suitable vaccuum port on inlet manifold, try to clamp other hoses/passages temporaily.

3. Rig up an air line attachment to the port with an inline valve to regulate supplied air to the cylinder.

4. Remove spark plug.

5. Slowly open valve. You should be able to feel air blowing out of the spark plug hole.

6. Run tap DRY into hole & slowly re-tap thread. All filings will be carried out with the air, so watch your eyes!

might take alittle bit depending on how bad the thread is. Using this method has worked EVERYTIME WITHOUT FAIL!!!!!!!!!

Plattsy Grand Master

Plattsy

Posted
  • Author
Posted

it doesn't seem to bad. its at a very slight angle, towards the front of the engine, i say i think its misfiring but not actually sure car drives perfectly, but we changed the knackered coil packs, and the one on that spark plug was cracked, and it seemed like it was because of the angle it was attached.its not a major issue, but its just gonna cost a fair bit if it keeps cracking coils.

cheers for all the input fellas, we just really dont have the tools or equipment to do it ourselves. rather pay out 100 bucks or so rather than having to forkout for a new head/gasket/ancillarys etc.

Plattsy Grand Master

Plattsy

Posted
  • Author
Posted

Ok, heres the best & EASIEST way to do it WITHOUT getting anything in the cylinder. I work in heavy engineering, & am an engineer. Showed an apprentice this trick yesterday after he f**ked an oil gallery plug hole on an installed crankshaft. (7,042 c.i. V12). Compressed air is required.

1. Bar engine over till intake valves for cylinder are open, exhaust valves closed.

2. Find a suitable vaccuum port on inlet manifold, try to clamp other hoses/passages temporaily.

3. Rig up an air line attachment to the port with an inline valve to regulate supplied air to the cylinder.

4. Remove spark plug.

5. Slowly open valve. You should be able to feel air blowing out of the spark plug hole.

6. Run tap DRY into hole & slowly re-tap thread. All filings will be carried out with the air, so watch your eyes!

might take alittle bit depending on how bad the thread is. Using this method has worked EVERYTIME WITHOUT FAIL!!!!!!!!!

shame your in sydney boss, otherwise we would be round with some beer for ya in exchange!

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