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Discussion Starter #1
I'm starting to sweat the possibility that my spark plugs are loose, or will loosen, after having them replaced in conjunction with a pulley. I read, perhaps here at MINI2, that someone had actually blown a plug right out of the head, after it had loosened, doing a lot of damage. I was just over at the Web Motorsports site, and a guy who had his pulley done the same weekend as mine, said ALL of his plugs loosened! Of course, tonight's project will be to check the tightness of my plugs; is the loosening of plugs a common problem? Does scheduled maintenance include checking the plug torque?
 

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Discussion Starter #2
So, nobody else was worried? I bought a ten-freaking-dollar extension for my ratchet, just to check the plugs. They were all nice and tight.
 

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Loose plugs?

RickB said:
So, nobody else was worried? I bought a ten-freaking-dollar extension for my ratchet, just to check the plugs. They were all nice and tight.
Rick, I think that was a warning to all who had changed out their plugs for the way over priced ones some vendors are pushing. Think about it a min. changing out a pulley isn't going to automatically cause your spark plugs to come loose and walk out of the head. I think this was the result of someone not knowing or paying attention to what they were doing while changing plugs.
 

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Spark plugs

Well how about that, I read through the entire post. What was common for the most part was that most stated they had their plugs changed at a pulley party or had changed out the plugs themselves.
In my experience with spark plugs in aluminum heads, always work on a cold engine, I mean over night cold, make sure the threads are clean no carbon build-up if dirty use a thread chaser, gap your own plugs do not rely on the manufacturer, use anti-seize on the threads and torque to spec.
I mention this only because this is most likely the severest enviornment for spark plugs and represents years of experience. After driving and maintaining VW air-cooled ( oil-cooled really ) Bugs for 8 years and doing side work tune-ups for others. I have seen it all, blown-out plugs, striped threads, cross-threaded plugs.<not on my cars> Aluminum expands when hot and shrinks when cold so if you put them in while the engine is warm they will not be as tight in the morning on start up and as this cycle continues day after day they will eventually become loose.
I have seen people strip treads removing plugs from a very warm to hot engine or change the plugs on a warm engine and have a plug blow out or leak compression a week later and there was nothing wrong with the threads.
 

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Norm03S -- Sorry for the dumb Q, but thread chaser? Another Q: With anti-seize would you still go to 18 - 21 ft-lbs? Appreciate the info.

I read most of the thread since I have 36K on my '03 and do a lot of trackdays, necessitating more often plug changes. I'm on my second set of cold plugs and was planning on changing them out this Winter as part of trackday downtime prep work.

Was wondering, with all the talk of pretty exact ft-lb torque values, how comfortable are you with your wheel torque wrench. I have an inch-pound wrench (Craftsman) that goes up to 250 inch-pounds, basically 21 pounds. Sounds like I'll finally have a use for it on my car. Just a thought.
 

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NearlyNN said:
Norm03S -- Sorry for the dumb Q, but thread chaser? Another Q: With anti-seize would you still go to 18 - 21 ft-lbs? Appreciate the info.

I read most of the thread since I have 36K on my '03 and do a lot of trackdays, necessitating more often plug changes. I'm on my second set of cold plugs and was planning on changing them out this Winter as part of trackday downtime prep work.

Was wondering, with all the talk of pretty exact ft-lb torque values, how comfortable are you with your wheel torque wrench. I have an inch-pound wrench (Craftsman) that goes up to 250 inch-pounds, basically 21 pounds. Sounds like I'll finally have a use for it on my car. Just a thought.
Hey Norm.
Thread chaser= Thread cleaning tool. Like a tap from a tap & die kit. A nice stiff bronze brush will work as well. You want a very short brush so you can run it all the way through and not have to try and reverse directions while in the thread bore.
Be very careful. Drop something and you're all f'd up.
Anti-sieze does not affect the torque spec. In fact you will get a truer reading.

A torque wrench will generally show it's greatest inaccuracy at it's maximum. So definitely don't set it to 21lbs/ft
I use 19lbs/ft and mine haven't come loose.
Norm03's guidelines are very good. Cold engine good.
 

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More about plugs

I agree with obehave's post.and would add he brough up a very good point about not having anything laying around that could possibly fall down into the open plug hole into the cylinder.
Let me add a little finesse to installing plugs,
Start your plugs using a plug socket that grips the plug and just an extension, gently lower into valve cover with fingers only until you feel the plug enter the plug hole, look at the extension to be sure it's centered. Then under it's own weight slightly turn counter clock wise 1/4-1/2 turn, then start turning it clock wise, you will feel the threads start (you can lift up slightly to make sure) if they are clean you should be able to turn it in until the plug bottoms with fingers only. Then do the next and so forth untill they are all in hand tight. Now per obehave's torque recommendations start at one end and torque them down, then go over them again, just for good measure.

Remember COLD engine.
 

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Discussion Starter #10
At the pulley parties, the plugs are put in no more than an hour after the engine was shut off, so the engine is still plenty warm. I was going to check them right after I returned with my extension, then decided to let it cool overnight. Since mine didn't loosen, I don't have much to complain about, and since the MINI doesn't require much maintenance, having a reason to poke around under the hood, checking the tighness of various caps, oil level, refilling the wiper reservoirs, etc., was kind of fun. I hope there are no MINIs out there with loose plugs, regardless of the cause.
 

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Thanks to all for this thread....I have been wanting to put it colder plugs since I got my pulley, but was deterred by the reports of possible problems....(I never had a problem with plugs I changed on my cars before, but :confused: )

Now I'm confident that I can do it with proper attention...thanks again :D
 

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IMO is virtually impossible for the sparkplug to come out if correctly fitted. Are we saying
its going to unwind itself 20 turns or so and blow out? Or that its going to rip 20 treads out
and exit without turning.? I would guess more likely whoever fitted them cross threaded it
and thought it was fully in 'cos it felt tight but actually it was in only a couple of turns.
Then it could rip its way out! The Mini has long reach threads on the plugs coupled with the fact the cars are all pretty new, IMO its extremly unlikely that Mini have created a truncated thread by using an oversize tapping drill by mistake. Thats the only way its going to rip its way out. For those who 'have to know the truth 'you can look up the tapping drill size ,then make a long 'go' and 'no-go' plug guage and check it easily yourself.
Finally if you re-use a plug it is possible for the gas to leak past the threads & the 're-used'
compressable washer. We found this on our Audi TT (running 30psi boost), the coils lift up. The cure was to use
copper slip on the thread which as well as lube the threads reclaimed a gastight seal.
Best Regards Roland Gt Tuning Ltd
 

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roland2003 said:
IMO is virtually impossible for the sparkplug to come out if correctly fitted. Are we saying
its going to unwind itself 20 turns or so and blow out? Or that its going to rip 20 treads out
and exit without turning.? I would guess more likely whoever fitted them cross threaded it
and thought it was fully in 'cos it felt tight but actually it was in only a couple of turns.
Then it could rip its way out! The Mini has long reach threads on the plugs coupled with the fact the cars are all pretty new, IMO its extremly unlikely that Mini have created a truncated thread by using an oversize tapping drill by mistake. Thats the only way its going to rip its way out. For those who 'have to know the truth 'you can look up the tapping drill size ,then make a long 'go' and 'no-go' plug guage and check it easily yourself.
Finally if you re-use a plug it is possible for the gas to leak past the threads & the 're-used'
compressable washer. We found this on our Audi TT (running 30psi boost), the coils lift up. The cure was to use
copper slip on the thread which as well as lube the threads reclaimed a gastight seal.
Best Regards Roland Gt Tuning Ltd
Key words " correctly fitted " and I agree. Did you notice the link Read this thread thanks to onasled for posting it.
Where the link is from is also interesting to note. I think this is where it all started.
 
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