Snapped spark plug
Discussion
Ok, so a little job yesterday in the sunshine has turned into nightmare.
I changed the plugs (I fitted the last set, always careful not to over tighten). 7 were a breeze, 1 snapped (the forward most one on the nearside if it makes any difference).
The centre of the plug has come out, leaving the thread. Today, full of hope and positive thinking I borrowed a set of easy-outs but I still cannot shift it.
Any ideas please?
(In Scotland and the car is a 1991 RRC 3.9 V8 auto).
Thanks.
I changed the plugs (I fitted the last set, always careful not to over tighten). 7 were a breeze, 1 snapped (the forward most one on the nearside if it makes any difference).
The centre of the plug has come out, leaving the thread. Today, full of hope and positive thinking I borrowed a set of easy-outs but I still cannot shift it.
Any ideas please?
(In Scotland and the car is a 1991 RRC 3.9 V8 auto).
Thanks.
I'm assuming it's seized with galvanic corrosion in the alloy head? Did you use graphite grease (or even a dab of copper grease) when you fitted the last lot?
If penetrating oil and easyouts won't shift it then you're probably getting towards the kind of stuff that makes swarf or fragments so you'd need the head off...
If penetrating oil and easyouts won't shift it then you're probably getting towards the kind of stuff that makes swarf or fragments so you'd need the head off...
A steel insert straight into an aluminium alloy hole will result in corrosion as the more reactive metal sacrifices itself to protect the other. This will in turn seize the two together.
It's good practise to run a light smear of graphite grease down the male thread before screwing it in. It'll distribute itself nicely and separate the steel from the aluminium alloy and prevent this happening.
Not a lot of use now, I realise, but you'll know next time.
Google "galvanic corrosion" or "dissimilar metals" if you want to know the whys and wherefors...
It's good practise to run a light smear of graphite grease down the male thread before screwing it in. It'll distribute itself nicely and separate the steel from the aluminium alloy and prevent this happening.
Not a lot of use now, I realise, but you'll know next time.
Google "galvanic corrosion" or "dissimilar metals" if you want to know the whys and wherefors...
JumboBeef said:
No, I didn't use any grease when they were fitted (I have just fitted new ones without, should I have used something? I always make sure I don't over tighten).
I'm not going to be a lot of use to helping you get it out, but for reference, the spark plugs on the RV8 only need to be tightened to 15 lb ft (20 NM). That's not much at all, and it's very easy to over-tighten if you don't use a torque wrench.Here's a thread when we broke a spark plug in the Ka: http://www.pistonheads.com/gassing/topic.asp?h=1&a... (solution on page 3).
Combination of ++soaking with penetrant spray and aggressive use of screw extractors. Gave it a properly decent couple of smacks with a hammer to fit in tight.
Worked in the end. HTH
Combination of ++soaking with penetrant spray and aggressive use of screw extractors. Gave it a properly decent couple of smacks with a hammer to fit in tight.
Worked in the end. HTH
I feel for you..... although my story wont make you feel happy....
I had a plug snap in exactly the same way....tried using easy outs the ones I had were just a little tight , got it stuck in the hole, got it removed after lots of swearing and basically whearing it away so it could be removed...
in the end drilled and tapped it, however the drill bit was just a little to short about 1mm no biggy the tap "should" push through and all will be well, so put it all back together, runs quite frankly like a bag of s
t, so now have had to remove the head to see what the issus was, found that the little push through with the tap has moved/bulged the head material in to the valve openings, so the valves dont close properly, so that'll be a new head then........ And to thing it was running okay until I did a quick bit of maintenace by tring to change the plugs this has been on going for about two weeks now, I have a head on order and all the stuff to rebuild it, so in a week or so I should be back on the road......
bullit
I had a plug snap in exactly the same way....tried using easy outs the ones I had were just a little tight , got it stuck in the hole, got it removed after lots of swearing and basically whearing it away so it could be removed...
in the end drilled and tapped it, however the drill bit was just a little to short about 1mm no biggy the tap "should" push through and all will be well, so put it all back together, runs quite frankly like a bag of s
t, so now have had to remove the head to see what the issus was, found that the little push through with the tap has moved/bulged the head material in to the valve openings, so the valves dont close properly, so that'll be a new head then........ And to thing it was running okay until I did a quick bit of maintenace by tring to change the plugs this has been on going for about two weeks now, I have a head on order and all the stuff to rebuild it, so in a week or so I should be back on the road......bullit
I have a tool for this purpose that has never failed (I was sceptical when I sold it) as mentioned above.
http://item.mobileweb.ebay.com/viewitem?itemId=171...
Sorry for the American link
http://item.mobileweb.ebay.com/viewitem?itemId=171...
Sorry for the American link
Update:
Admitted defeat and got it sent to a local "old-school" garage. The old plug was cross threaded (which numpty did that then?
) but they finally managed to get it out. New plug fitted and now running like a good 'un.
£110 lighter, but much cheaper than getting the head off!
Thanks for all the replies/ideas.
Admitted defeat and got it sent to a local "old-school" garage. The old plug was cross threaded (which numpty did that then?
) but they finally managed to get it out. New plug fitted and now running like a good 'un.£110 lighter, but much cheaper than getting the head off!
Thanks for all the replies/ideas.
I very much doubt it was cross threaded. A cross threaded anything will only turn about 180 degrees before it jams. Brute force will/can force it in, but you'd as sure as hell know you were forcing it. Plus, when removed, the thread will be damaged, and it'll require a Heli-Coil to repair. £110 seems a bit costly !!
JumboBeef said:
Update:
Admitted defeat and got it sent to a local "old-school" garage. The old plug was cross threaded (which numpty did that then? ) but they finally managed to get it out. New plug fitted and now running like a good 'un.
£110 lighter, but much cheaper than getting the head off!
Thanks for all the replies/ideas.
You were lucky, an AA man cross threaded one of the plugs in my old 911 when cleaning them due to rough running. Worked fine until the next service when it snapped when the garage were replacing it. £4K bill later it was ok, however all the ancillaries started mucking about. Alternator failed after a few weeks, etc. and it was never reliable again. Bloody AA man.Admitted defeat and got it sent to a local "old-school" garage. The old plug was cross threaded (which numpty did that then?
) but they finally managed to get it out. New plug fitted and now running like a good 'un.£110 lighter, but much cheaper than getting the head off!
Thanks for all the replies/ideas.
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