So one of my spark plugs on my 2002 Cooper decided it was too good to just stay on the Cylinder head. After a quick look I thought it worked its way loose with vibration but it completly striped out the head.
Dealer price is too much to even think about so I was wondering if anyone had an issue like this or if anyone can recomend a good machine shop that I can send the head to.
Also I must admit 86+ miles on my Cooper and this is the first issue I ever had with it. But I also just noticed the air bag light turns on when a passenger sits there so I guess the car is a one seater.

 

https://www.northamericanmotoring.co...ad.php?t=75936

Me too... fixed mine with a friend's help for $3.31.

 

Have someone who has done this before help you.

Use a Helicoil or other spark plug rethread kit. A machine shop won't help too much - it'll just be expensive and cumbersome. Do a web search on Helicoil to get an idea how people feel about. After my own research, I feel pretty good about it. I fixed mine last night and drove 55 miles to work today with it. No problems.

In the future, occasionally retorque your spark plugs.

 

Again, was this an original plug that was installed at the factory, or an aftermarket plug installed after delivery?

It's all in the details....


Rock on,

-boognish

 

These where Bosch 4 point Platnium plugs installed by ASE Master Tech at local shop. Dealer too far for a small tune up. It was done over a year ago too.

 

I had a shop fix it... But in discussing it I got a few interesting pointers.. Most said it was impossible to fix the head on the car without huge risk, but others didn't agree. To catch the chips, first stuff some panty hose into the combustion chamber. Grease the tap for the helicoil to hold most of the chips, and do your thing. Then use tweezers or some hemostats to grab the panty hose scrap, and any other chips will stick into the webbing!

Sounds pretty cool.

And yes, recheck the plugs every so often...... (matt types wondering when the last time I did it was.....)

Matt

 

I hate it when that happens!

 

Has anyone had a long term sucess with Helicoil?

 

I've had mine in for a couple of years. Acutally, when I do plug stuff, that cylinder feels the best as I torque them into the head.....

Matt

 

I watched eBay and the marketplace for a good deal on a head. I got a JCW take off (very low miles) off eBay for $300. It's off getting ported and polished as I type.....

But the repair worked, and gave me lots of time to find a good path for upgrading my head in the process....

Matt

 

If you go the Helicoil thread repair route, you must remove the head to do so. You till be tapping a new (and unique) thread into the spark plug hole, to thread the Helicoil into. The metal shavings from the tap WILL fall into the cylinder if you try this while the head is on the engine.

 

Nice pointers! That's a great way to have some piece of mind!

 

I have used the KD Back-tap spark plug thread tool with great success. Check it out on page 4 of their catalog.

http://www.kd-tools.com/PDF/KDSuppCat03.pdf

Essentially it lets you use the good threads at the bottom of the hole and tap backwards. It works and it is easy to do on the Mini as there is plenty of space. If you want to stuff a stocking in there for insurance, no problem. But I tried an old head before I did it on a friends car and with grease there were no chips at all going inside. Everything was carried out the top. It's a great tool to have when you need it.

Good luck.

Rich

 

Thanks for reminding me to go out and check my plugs!

What is the torque setting? 18 pounds?

 

I use 23, Andrew.

just looked it up in Bentley..they say 27 Nm (20 ft lbs) . my response above was from Randy Webb(???)

 

All good solutions. I, however, am a firm believer in Murphy's Law, and would go through the hassle of pulling the head to assure myself that NO shavings or chips found their way into the cylinder. Cheaper than major engine work later.

 

Thank you all for your help. I think that trying the KD Backtap is a good start but I will still use the stocking in the cylinder and grease to catch all the shavings.

In my travels today online I found www.cylinder-heads.com and the guys there tell me if I send them the head they will repair and send it back to me like new for $250 plus $20 shipping costs. But my concerns with pulling the head off is getting the timming correct.

 

Rich, there are 5 diffrent ones. What model number did you use?

Thanks,
Lou

 

The Mini plugs are 14mm so the BackTap is the 3545. That said I didn't do it on a Mini. We did it on a Subaru. Also with aluminum heads. And although we did not stuff a stocking in there we did vacuum out the cylinder when we were done.

This is one miracle tool when you need it. I have not seen a Mini head with a blown plug but I have to assume there are lots of threads left at the bottom that should hold a plug in. That said, the correct way to fix this is to take the head off and put in a helicoil. The Subaru we did had cross-threaded threads from an inexperienced install and as far as we know the car is still going strong with only the rethreaded plug hole.

The lesson learned is to torque the plugs in at 20lbs. I check mine at each oil change and fortunately none of mine have come loose in the 15000 miles since I put in the IK20s.

Rich

 

You beat me to it... This is a great tool & works as advertised.
Rick you're Da-Man

 

Nice catalog and a very Interesting tool.

Does this tool insert a helicoil or something?

Otherwise, assuming the plug has ripped all the threads within it's reach out, how does this tool find threads to move up into place again so the plug will stay in?

Inquiring minds want to know...



Best,

-- Don

 

Exactly: it doesn't. It's a well thought out solution for rectifying deformed threads, but if they're stripped, they're gone for ever. Then you need to use a threaded insert such as a Helicoil, TimeSert etc.

Note that when properly installed, inserts are typically stronger than the original threads they replace, both because of the larger external diameter which offers greater purchase in the head and because they're steel rather than aluminum.

Installing spark plug hole thread inserts with the head in place is common practice. I know it sounds nasty, but even if a few thread cuttings do find their way into the combustion chamber despite the proper precautions, they'll usually be digested without harm. These are, after all, fine cuttings of very soft aluminum.

Neil
05 MCS
96 M3

 

Thanks for the explanation, Niel...

I've not had to address this yet with my 06, but I figure as long as a car uses spark plugs this could happen, so I like knowing what the alternatives are...

Like many here I've got a pulley. One messager on this same topic (but a different active thread: "Spark Plug Ejection Button") was questioning if increased head pressure from a pulley can contribute to popping a plug...

Is head pressure really increased with a pulley? Or do the injectors and the SC blow-out valve buffer the added pressure so really all we get is a better air/fuel mix?

My guess is we'd probably blow a head gasket first if there was a pressure problem, unless the plugs are loose. And if they are loose, any engine would pop them out, pulley'd or not... Does that sound rational?

With the masses that use pulleys, including JCW and Dinan installed by dealerships, if there were a problem related to using them everyone would be screaming about them by now.

Ultimately it sounds like the real source of this problem is pure and simple, loose plugs...

Thanks again,

-- Don

 

yeah, combustion chamber pressures do go up. That's what makes the increased power.

Also, the bypass valve on our cars doesn't work like a blow off valve on a turbo. For the turbo, you use them to dump boost when you take your foot off the gas. On our car, it's there to allow the SC to be removed from the loop (somewhat) at light load conditions, but has no fucntion at all in limiting boost at WOT. The SC boost is naturally reduced as the RPMs drop due to direct coupling, whereas with a turbo the inertia of the turbine keeps it spinning fast as the motor slows...

Popping plugs is a known problem in Minis. It's happened in other heads as well (one of the Ford 4.6 V8s had the same issue). Not sure if it's the metal composition/temper or the thread count, but the Mini head isn't great in this regards.

Matt

 

Hey Matt,

Do the chamber pressures go up to a point of being a problem?

The reason I ask is that I've always wondered why the JCW and Dynan performance packages include a different head along with their SC pulley. Do they do so because of pressure, or are there other tweaks that they wanted to get in?

Hmmm, sorry for the topic hyjack...

Best,

-- Don