Spark plug problem - cylinder head needs replacing

[fulle156]

Hi folks,

Nightmare scenario here. I was driving down the M7 (Ireland's version) last Friday night when all of a sudden, a bang form the bonnet and the car starts to sound more like a Massey Ferguson tractor than a Mini. I pulled in, popped the bonnet and theres the sparkplug sitting on the supercharger, completely out of the cylinder. After being towed to the nearest mechanic, he had a look at it and said that'll cost a fair bit - the top of the spark plug had sheared and also the cylinder head wasn't biting any more so not even a temporary heal would suffice. Shes in a Mini garage in Kildare now, they called this morning, 3,165 euro to get the cylinder head replaced.

I nearly dropped the phone.

Has anyone ever had a similar problem to this? The mechanics never heard of such a thing happening. Shes a Cooper S, 32,000 miles on the clock - 2003 - minded well, not being pushed hard at the time on the motorway.
Does anyone know what would cause such a thing? Any ideas, tips or cash donations would be welcome!!!

Happy motoring all.

[Jaw_F430]

Quote: Originally Posted by fulle156 (original)

Hi folks,

Nightmare scenario here. I was driving down the M7 (Ireland's version) last Friday night when all of a sudden, a bang form the bonnet and the car starts to sound more like a Massey Ferguson tractor than a Mini. I pulled in, popped the bonnet and theres the sparkplug sitting on the supercharger, completely out of the cylinder. After being towed to the nearest mechanic, he had a look at it and said that'll cost a fair bit - the top of the spark plug had sheared and also the cylinder head wasn't biting any more so not even a temporary heal would suffice. Shes in a Mini garage in Kildare now, they called this morning, 3,165 euro to get the cylinder head replaced.

I nearly dropped the phone.

Has anyone ever had a similar problem to this? The mechanics never heard of such a thing happening. Shes a Cooper S, 32,000 miles on the clock - 2003 - minded well, not being pushed hard at the time on the motorway.
Does anyone know what would cause such a thing? Any ideas, tips or cash donations would be welcome!!!

Happy motoring all.

Buy a cylinder head off ebay and then get it fitted, will be a lot cheaper


Regards


James

[DaFlake]

Common problem. I'm willing to bet you were running after market plugs as well; am I right?

Here is the best advice I can give you. Collect your car from the dealer (you are out of warranty right?) and find a mechanic that can either to a helicoil or a backtap to put new threads in. This will actually be as strong or stronger than the original and will cost about 300 USD (going rate in the states).

There is no need to buy a new head and for that amount of money you can put in a performance head.

[Jaw_F430]

Nearly new heads (del miles) go on ebay for around £50.

[DaFlake]

Quote: Originally Posted by Jaw_F430 (original)

Nearly new heads (del miles) go on ebay for around £50.

The problem can reoccur with a new head. As I said, helicoils and backtaps are stronger so it is best just to repair it as it won't happen again after that. Personally, I would have all four done and the cost of having the head replaced will be pretty expensive. The above can be done with the head on the car, no need to remove it.

Lastly, you have no idea what you are getting from EBay...

[oldmots]

I would investigate and find out what happened to the threads in the head. If I had to guess, just the top thread or two may be damaged when the plug blew out. If you put a tap in and clean it up at the top, it may be fine, you have nothing to lose in trying. A long reach plug like this has too many threads to blow out from the bottom, it had to be right at the top when it went. I would cast a suspicious eye on anyone quoting a price this high for this simple repair! If it were me, I would collect my stuff and hit the road for better help. I like to guess how things happened, and the only thing I can think of on this one is that there was some thread damage in the head and at the last plug change, the plug did not get screwed in all the way and it worked itself back out.

[Rich.Wolfson]

Quote: Originally Posted by oldmots (original)

I would investigate and find out what happened to the threads in the head. If I had to guess, just the top thread or two may be damaged when the plug blew out. If you put a tap in and clean it up at the top, it may be fine, you have nothing to lose in trying.

The KD Backtap taps from the bottom up. It has a lot less chance of allowing chips into the cylinder head. The Mini plugs are 14mm so the BackTap is the 3545 and you can find one with a Google search. A friend of mine came to me with a blown plug and we used the Backtap and it has not come loose again and has been no problem. We did it on a cold head and it was much easier than a helicoil.

It seems to me that the Mini heads might be a little soft when hot and over tightening a plug when the head is hot is looking for trouble. The proper torque is 20ft/lbs and it is critical that they are not over tightened which is easy unless you use a torque wrench. It is also a good idea to check them once in a while as this, unfortunately, seems not to be an uncommon problem.

If the backtap doesn't work, then Helicoils or Timesert which in experienced hands can both be installed without taking off the head. Either would be much cheaper than a replacement head.

Rich

[oldmots]

Great Suggestion! I learned something new, I did not know about this special tool.

[Randall Raines]

Quote: Originally Posted by DaFlake (original)

The problem can reoccur with a new head. As I said, helicoils and backtaps are stronger so it is best just to repair it as it won't happen again after that. Personally, I would have all four done and the cost of having the head replaced will be pretty expensive. The above can be done with the head on the car, no need to remove it.

Quote: Originally Posted by Rich.Wolfson (original)

The KD Backtap taps from the bottom up. It has a lot less chance of allowing chips into the cylinder head. The Mini plugs are 14mm so the BackTap is the 3545 and you can find one with a Google search. A friend of mine came to me with a blown plug and we used the Backtap and it has not come loose again and has been no problem. We did it on a cold head and it was much easier than a helicoil.

It seems to me that the Mini heads might be a little soft when hot and over tightening a plug when the head is hot is looking for trouble. The proper torque is 20ft/lbs and it is critical that they are not over tightened which is easy unless you use a torque wrench. It is also a good idea to check them once in a while as this, unfortunately, seems not to be an uncommon problem.

If the backtap doesn't work, then Helicoils or Timesert which in experienced hands can both be installed without taking off the head. Either would be much cheaper than a replacement head.

Rich

What he & he said .

I've used the Helicoils in the past (because of damage or someone else's incompetence, not mine) and swear by them, just re-threading the hole can & does sometimes work and make a thread good again, but there will still be some sort of damage there and it may never be as strong as it was originally (the thread) however the Helicoils replace the thread and are stronger than the original thread especially in the case of aluminium, however a very good-point that needs to be considered that I've just seen on an article was, what happens if the item (spark-plug / bolt etc...) seizes to the Helicoil which could happen this is even more important in the case of park-plugs, as they have to be removed periodically (not just tightened back up once and forgotten about).

I came across something similar once. A friend had a car and a couple of the plugs were loose he tightened them up and then decided to change them, while removing one of them he managed to snap the top of the spark-plug off (I was expecting the porcelain top to have broken off), he had actually snapped the top off, nut / bolt part inc..., leaving the tread seized in the cylinder-head .

Quote: Originally Posted by DaFlake (original)

Lastly, you have no idea what you are getting from EBay...

That is the best piece of advice of all, you may even be getting a cylinder-head which may have been removed because of a similar fault (if not worse) .

[Damo]

Anyone know who can do this in the UK?

[fulle156]

Thank you for all your excellent info and help. I now have three options with this issue and again would love to hear your thoughts. Before I go through them, a thing or two to note. The MCS I have was tuned by BBR in the UK, a phase 1 conversion was done in 05, shes up to 200bhp at the moment. This conversion was done before I bought the car.
She does have after market sparkplugs which BMW have refused to warranty, understandable.

1) Get the car repaired by the local BMW dealer and have the standard sparkplugs put in and the cylinder head replaced for 3500 euro, resulting in the good work of the tuning co. being undone considerably and the car not as much fun as it was previously

2) I rang the tuning co in the UK - they said they could do the same and restore her to her former glory for 2600 euro, new cylinder head and performance plugs

3) Go to the tuning co in the UK, go the whole hog and get phase two of the conversion, and beef the Coop up to 240bhp and bring her to new heights, replacing the bits and pieces that needed doing before for 4500 euro.

Two and three are dependent on getting some decent warranty on the work from that company, of course, as this can't be a regular occurence.

Now, again I would love to hear your views on this one. Should I cut my losses and play it safe or perhaps take a long term economical viewpoint and instead of injuring the cars rep (were I to sell it in future) I could seize the opportunity to improve it. What do you think? Too risky? No contest? Let me know please.

[DaFlake]

If money is not an option then three is your option but I still don't understand why you are willing to spend that much money on a repair that should only cost a few hundred quid. It is your money though and if you want to spend it who am I to stop you....

[Damo]

In the middle of getting my repaired at the moment and the repair should cost less than £100

However I'm only using it as a temporary measure and looking into getting a performance head in the future now (along with manifold and cam).

However the new car tax for 2009 may have put a dampner on that

[fulle156]

DaFlake and Damo, unfortunately having spoken to the garage about doing such job, they just won't allow it. Nor, so far, can I find a mechanic that will do it. Besides, were I to sell the car in later, I couldn't in good conscience sell it on with a repair job that I couldn't be certain of.
So its not like I want to spend that much money, but the way I figure it, if I have to spend 3500 I might as well go that bit extra and actually improve the car.
I know what you're saying and thank you for all your advice. The job is a real pain in the ass considering the timing of it personally, but out of curiosity how can you really give an accurate diagnosis without seeing the actual damage done to the engine?

[DaFlake]

If you spoke to a MINI dealer. no, they won't do it. They want your money and aren't going to recommend it. People have been doing this for decades with no ill affect to the engine or drive of the vehicle. If you are not tracking the car then a helicoil is a much better solution and when you sell, you simply disclose it as you would any other repair. What would happen if you were installing plugs and cross threaded one? Would you spend the 3000 to buy a new head?

On the diagnosis side, you popped a plug unless there is something that you are not telling us (like Nitrous or something). This is not a MINI specific problem. My Escort had this happen at 20K and when I sold it, it had over 120K. So, the choice is yours and we simply offered up a money saving solution that has no ill effect on your MINI.

Oh and just to let you know, if you do fit a non-MINI head in your car you are now modding it. You need to check with your insurance to make sure they will cover it (I assume that is what you meant by improving the car) and it may also devalue the car when you go to sell as most people will think that you have been racing it.

You might also want to search MINI COOPER :: North American Motoring for the Heli-Coil or Backtap and see what it turns up.

Just to add, I did it myself on the Escort and 3 years ago the car was still running around town on the same engine. (It was a 92 Escort)