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spark plug cross threaded - URGENT ADVICE NEEDED

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mrr1
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PostPosted: 22:09 - 27 Feb 2011    Post subject: spark plug cross threaded - URGENT ADVICE NEEDED Reply with quote

right - here's my problem - bikes been missing a little when damp so I refitted HT leadto cap, whipped out plug, cleaned electrode and checked gap. Thought I'd check cylinder no 2 (bike is 2000 fazer 600 with 29k on clock). As I was putting spark plug back into cylinder 2 it felt a little stiff so I backed it back out, wound it in with fingers half a turn and then ratcheted it in (but being a feckwit ignored the fact that it was still stiffer than normal). Then noticed plug was at a crooked angle to the one on cylinder 1 and about 10mm higher. So I took the plug out again and, sure enough, leading edge on plug is now shiny and I've cut myself a new plug thread - major f******g bo**ocks"!!!!!!!!!!! Is this an engine out job now? I've got a tap & die set and a vacuum attachment that can get into the cylinder. The main problem is getting to the top of the engine - its a complete b@stard with all the harnesses and frame in the way.

Any advice greatly appreciated......
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Ed Case
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PostPosted: 22:46 - 27 Feb 2011    Post subject: Reply with quote

You're dead right, it's a tw@ of a job, I've got a Timecert in the plughole of my 250RSA but I had to take the head off to do it properly, I suspect you'll have to do something similar unless you can find a particularly adventurous mechanic. Tuff my mate !. Sad
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Pete.
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PostPosted: 22:53 - 27 Feb 2011    Post subject: Reply with quote

You could run a tap down the thread. Another thing you could do is grind a fresh sparkplug thread with 3 or 4 flats on it to make the shape of a threadcutting tap and run that into the hole to clean up the first part of the threads that are crossed. Both methods depend heavily on the person doing the work knowing when they have got it right or wrong. Not much to lose by trying it but having someone good at dealing with such things on the spenner will vastly increase the chance of not having to pull the head off.
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mrr1
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PostPosted: 23:00 - 27 Feb 2011    Post subject: Reply with quote

cheers chaps. Reckon I'll try dropping the engine out one side of the frame and trying to tap a new thread in. One of the biggest probs is bloody access - there's just no space. For the two or so hours to get the engine out I can't see any option.

The other fear is letting shitty little bits of thread metal drop into the bore. As I said before I've got a DIY Hoover attachment that will neatly go through the spark plug hole into the bore to try & suck any shite out I'm not sure if that's really safe???
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Syris D Indomitable
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PostPosted: 23:10 - 27 Feb 2011    Post subject: Reply with quote

Yeah safer to take the head off, gaskets are only a few quid.
Just threaded a cam cover bolt hole my self. Lucky for me there's another 14 bolts holding it down, getting some apoxy metal compound tomoz for a propper botch job!
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mrr1
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PostPosted: 00:25 - 28 Feb 2011    Post subject: Reply with quote

sh1tty sh1t Mc f******g sh1t


how much of a tw@t is taking a fazer head off? Will I need the engine fully out? Will I need a new head gasket if I take the head off?

And all because I thought I'd have a f******g look at a plug colour.....




B@ST@RD
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mrr1
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PostPosted: 00:27 - 28 Feb 2011    Post subject: Reply with quote

and another question - is a plug thread the same as a normal 10mm bolt?
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kestrel
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PostPosted: 00:39 - 28 Feb 2011    Post subject: Reply with quote

Once you get the head off try running a spark plug thread chaser down the hole. If the plug became tight after just a few turns then you might get away with chasing it out. Google spark plug thread chaser, they only cost five or six quid.
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Raffles
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PostPosted: 08:39 - 28 Feb 2011    Post subject: Reply with quote

kestrel wrote:
Once you get the head off try running a spark plug thread chaser down the hole. If the plug became tight after just a few turns then you might get away with chasing it out. Google spark plug thread chaser, they only cost five or six quid.

This would be my first choice of action. I recently bought such an item from Machine Mart.
A good tip is to coat the reamer with grease making sure that the flutes are well packed. This will help to collect any swarf that is produced.
Remember to work very slowly and to keep backing the reamer out in order to clean it and to re-apply fresh grease.
Best of luck.
https://www.machinemart.co.uk/shop/product/details/cht261-spark-plug-thread-chaser
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Pete.
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PostPosted: 11:48 - 28 Feb 2011    Post subject: Reply with quote

I wouldn't take off the head, I'd have a crack at straightening the plug thread first then stuff a small tube up a hoover pipe to get any bits off the piston.

The CR8e standard Fazer plugs are fine thread, non-standard so don't go just buying a standard M10 tap and running it into the hole.
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mrr1
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PostPosted: 14:20 - 28 Feb 2011    Post subject: Reply with quote

I've though about that but the problem is I just can't be sure to get the tap straight because of access to the hole. Even with the rad and forks off it'll be a bitch. I'm thinking either

a - pull head off, get plug chaser (£6 from Rapid) and retap from bore side to make sure threads are straight

b - pull head off and get an insert dropped in. Reliable garage round the corner has just quoted £15 to put a Time sert in.

I'm really nervous about how much ali I've taken off the side of the plug hole and I wouldn't want a plug popping out at speed and going straight through the middle of my tank so I'm thinking the time sert is teh better option. Also I'd like to get a vacuum into the empty bore just to be sure there's no swarf in there.

I just wish I had Sky+ on my life so I could rewind things a couple of hours and leave the bloody plug in place.

Christ - there's a good idea for Dragons Den - Real Life Sky+............
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mrr1
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PostPosted: 20:41 - 28 Feb 2011    Post subject: Reply with quote

chr15 - whats that thing about spraying a gasket with primer to reuse it?

a lad I work with has got an old 911 and he was telling me both surfaces are just highly polished and there isn't a head gasket. Maybe I could try that - bit of extra compression as well!!!
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deliriousthun...
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PostPosted: 21:20 - 28 Feb 2011    Post subject: Reply with quote

Quote:
a lad I work with has got an old 911 and he was telling me both surfaces are just highly polished and there isn't a head gasket


No. Just no.

Do not run your engine without a head gasket, they are there for a very good reason. You will never achieve a proper seal on two metal surfaces by polishing them.

Afaik the only way to get a good seal on 2 metal surfaces is to freeze a solid shape, then crack it along the plane that you want to seal. Then when they warm up they are a perfect match for each other to mate together again. Wouldn't work on something as big as an engine block though.
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Pete.
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PostPosted: 21:31 - 28 Feb 2011    Post subject: Reply with quote

The early 911 heads were gasket sealed, later sealed with a special ring-type gasket. Didn't stop them blowing though and they ended-up welding the heads to the barrels during production for other models.
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mrr1
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PostPosted: 22:57 - 28 Feb 2011    Post subject: Reply with quote

I was only joking about the gasket - I might be mentally challenged in many ways but I'm not quite that daft.

Tomorrows the big day - local garage is ready to drop the time sert in. Should they be able to do it if I just take them the whole engine or will they need the head on its own.The more I read the serviice manual the more my undergarments change colour.
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ZRX61
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PostPosted: 00:39 - 01 Mar 2011    Post subject: Reply with quote

deliriousthunder wrote:
No. Just no.

Do not run your engine without a head gasket, they are there for a very good reason. You will never achieve a proper seal on two metal surfaces by polishing them.


Boss 429's don't use headgaskets...
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mrr1
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PostPosted: 01:00 - 01 Mar 2011    Post subject: Reply with quote

just been having a poke around - I've disconnected the 800 odd harnesses and moved them out of the way, the stat housing as well.Frig me - you can actually get to the top of the block. Tomorrow is time sert day.How much access will the garage need?
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Pete.
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PostPosted: 06:44 - 01 Mar 2011    Post subject: Reply with quote

There should be no need for a timesert. You should have at a guess about 8 threads of engagement on the plug , you couldn't have wrecked more than the first couple or the plug would still be frozen in there. There's no chance of an ejected plug at speed and no chance of it firing into the tank if it did either - all the enegry will be soaked-up by the pluglead.

Running a tap down the hole would be enough.
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Stalk
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PostPosted: 11:10 - 01 Mar 2011    Post subject: Reply with quote

I know that this is probably a bit late but if you where to turn the engine until the exaust valves on that cylinder where open, put your hoover on blow. Point that up your exaust pipe. Would that not then blow any swarf out as you are doing the recutting to the spark plug thread?
I have assumed that the exaust is in good congition and that no crud will come from the exaust into the cylinder. This is theoretical, I have never tried it.

Opinions?

Cheers
Stalk
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DrDonnyBrago
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PostPosted: 11:30 - 01 Mar 2011    Post subject: Reply with quote

Stalk wrote:
I know that this is probably a bit late but if you where to turn the engine until the exaust valves on that cylinder where open, put your hoover on blow. Point that up your exaust pipe. Would that not then blow any swarf out as you are doing the recutting to the spark plug thread?
I have assumed that the exaust is in good congition and that no crud will come from the exaust into the cylinder. This is theoretical, I have never tried it.

Opinions?

Cheers
Stalk


Lol.
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deliriousthun...
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PostPosted: 11:35 - 01 Mar 2011    Post subject: Reply with quote

Quote:
Boss 429's don't use headgaskets...


Yes, because they use a series of o-ring type seals instead, not because the metal surfaces are polished enough to attain a seal on their own.

There are engines in which 2 polished metal surfaces are used as a 'seal' but not without other o-rings in place. Not as far as I know anyway.

You cannot attain a proper seal by polishing surfaces. I'm pretty certain I'm not wrong about this, but if someone can show me otherwise I will stand corrected, (not in it for an argument).
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chris-red
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PostPosted: 11:44 - 01 Mar 2011    Post subject: Reply with quote

For the sake of £35 you might as well change the HG IMO.
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mrr1
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PostPosted: 12:39 - 01 Mar 2011    Post subject: Reply with quote

hmmmm...sounds a bit dodgy that........ I've got a vacuum attachment that will fit through the plug hole although I believe the best way to clean out a bore is to turn the crank until you open the exhaust valves and blow loads of air in. as it happens I've taken the downpipes off to get them welded at work so its no hassle to feel for air coming through with the exhaust valves being opened.

Also - how do you turn a vacuum onto blow?
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HD
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PostPosted: 13:17 - 01 Mar 2011    Post subject: Reply with quote

What I would personally do is wind the spark plug up from the engine side outwards? Or are the threads one sided?
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