had a bad misfire develop on my 2001 mini one all of a sudden,

found the cause was a broken valve spring on cylinder 4,

i have decent mechanical knowledge but i have never changed a valve spring before,

is it a handy job at home?

any decent guides to it?

thanks, andy

Hi Andy,

Just had the same bad news. My friend owns a garage and has quoted £1100 and that is if they can keep the cylinder head in place. For that all the valve springs and rockers will be replaced. It most likely happened due to thickening of the oil clogging the oil feeds, the oil was a little low when I got it in August, so I topped it up but it looks like the damage was done.

Hi Andy,

Just had the same bad news. My friend owns a garage and has quoted £1100 and that is if they can keep the cylinder head in place. For that all the valve springs and rockers will be replaced. It most likely happened due to thickening of the oil clogging the oil feeds, the oil was a little low when I got it in August, so I topped it up but it looks like the damage was done.

Changed many valves and springs in my earlier life as a mechanic. You need a valve spring compressor to allow removal of the valve collets. The valve spring can then be withdrawn, along with the valve itself. I would have thought the cylinder head staying in place was impossible. The spring compressor, shaped like a 'G' clamp, has to make contact with the outermost face of the valve. The clamp then screws down to compress the spring.

It is possible to change a valve spring without taking the head off, Ive done it myself years ago on my dads 68 Hillman Hunter.
To do it you need to remove a spark plug on the affected cylinder and turn the engine so the pistons are halfway down the bore with both valves closed on that cylinder.
Then feed a length of cord/string into the cylinder through the spark plug hole as much as you can get in leaving a bit hanging out so you can retrieve it later.
Then turn the engine so the piston comes back up crushing the string against the head and the piston, (this well stop the valve falling into the cylinder when you remove the spring cap and collets).
Then using a suitable spanner press down or make up an improvised lever to do the same so you can compress the valve spring to remove the collets and thus remove the broken spring.
Renew spring and reverse the above procedure making sure when youve done you remove the string from the bore and refit the spark plug.
It works, we did it and saved head removal.

The in place head method is as above, however he is using a tool from his Aston Martin days that bolts to another part of the head to give leverage so it can stay in place. All 16 springs and thier corisponding rockers are being changed just in case and he expects it to come in we'll under the £1100 he quoted, that was just going by BMWs rough guide lines.

It is possible to change a valve spring without taking the head off, Ive done it myself years ago on my dads 68 Hillman Hunter.
To do it you need to remove a spark plug on the affected cylinder and turn the engine so the pistons are halfway down the bore with both valves closed on that cylinder.
Then feed a length of cord/string into the cylinder through the spark plug hole as much as you can get in leaving a bit hanging out so you can retrieve it later.
Then turn the engine so the piston comes back up crushing the string against the head and the piston, (this well stop the valve falling into the cylinder when you remove the spring cap and collets).
Then using a suitable spanner press down or make up an improvised lever to do the same so you can compress the valve spring to remove the collets and thus remove the broken spring.
Renew spring and reverse the above procedure making sure when youve done you remove the string from the bore and refit the spark plug.
It works, we did it and saved head removal.

Well, they say you learn something everyday. I would have thought of that in a million. A can't say I've seen valve spring string in Halfolds though:)

however he is using a tool from his Aston Martin days that bolts to another part of the head to give leverage so it can stay in place. come in we'll under the £1100 he quoted,

Hmm sounds like hes still thinking Aston prices too? obviously Aston special tools are a bit steep too.
I know they do all sorts of mad things when servicing Astons, like renewing all the brake calipers too each time they change a brake pad.

can't say I've seen valve spring string in Halfolds though:)

Its special string not just any old bit, otherwise you would be able to do the job without it costing anything, and I dont think thats allowed these days, is it? ;)

He's quoted me for all 16 springs, rockers, valve stems etc and a max amount of time, it shoul however take a lot less so cost less, he's just going by BMWs time guide.

He's quoted me for all 16 springs, rockers, valve stems etc and a max amount of time, it shoul however take a lot less so cost less, he's just going by BMWs time guide.

A word of warning. Get a firm price in writing. You say he's doing all 16 valve springs. Have you got any idea how much string he will be using ? String prices are at an all time high at the moment. Also, think of the implications of using so much string. Parcels will come undone, yo yo's will be left in toy boxes with children crying all over the land and not to mention that vagrants trousers will keep falling down. I hope you can live with yourself. :)