Seized spark plug

Well, they aren't taper fit, and it is an alloy head.

Looks like it might be tricky....

IME they come out OK, so f it's stuck, it will be!.

I'd go for a rattle gun set to a low torque and hope it 'shocked' the plug out. When that didn't work I'd increase the torque progressively until something gave and then wish I'd used some heat as well (although I doubt it would be possible to get anything hot under these circumstances.)

change the ones you can, put a puddle of thin oil (penetrating oil will just evaporate) around the stuck one and use the car, after a week or two, with the engine hot try to undo it, preferably use a T bar socket drive so that the force is a twist rather than a lever, likewise use half inch drive rather than 3/8 (as 3/8 bars wind up to some extent). If this fails then you have little choice but to try an air impact gun (just make sure it is in reverse)

Mrcheerful

Fortunately, if you can change 3 of the plugs and the 4th one is firing, then time is on your side. I would do what Mr C says, several times. Also keep trying it every couple of days. Also try giving it a *little* turn in the opposite direction, ie tending to tighten it. Then reverse the ratchet and go for loosen again. I would leave the air tools in the garage for this problem.

Steve

All sorted now. Gave it a good squirt with plusgas on Sunday night, got a bit more put on this morning, and then lathered it with Loctite freezer spray or whatever they call it. It was going to be very difficult to use heat as it'd mean getting a blowtorch next to a load of hoses I'd just replaced and refilled with new coolant, so I bought the freezer spray despite thinking it sounded too good to be true. The spark plug undid with a fairly hard heave on the bar, and all was well again.

I'm not sure leaving 1 of the 4 in would have been an option, as there was very heavy oil fouling, erosion of the electrode and unburnt petrol spouting flames out of the exhaust on the overrun...

Has it got a cat?

On a Mk2 Golf, I dont think so! lol.

Tim.

Glad you got it out Doki, I reckon the moral of this story is a bit of appropriate grease will save you a headache.

The proper greezer spray is deadly. You have to use it carefully or it can actually give you freeze burns.

Conor wrote in news: snipped-for-privacy@news.individual.net:

LOL, I read that as geezer spray !!!

ROFL. Can just imagine all the Essex Boyz queuing up for some.

Well as sorted reply not needed now but I was going to suggest maybe trying a 12 pointed plug socket - rather that the standard 6 flat things. (Dunno where you can get such a thing from mind(.

Any reason why that would help? The advantage of a 12 pointed socket is it's easier to put on - but since in this case there's no access problems, there's no gain to be had there.

cheers, clive

I find the grip is better. The hex sided tend to rotate to 1 point of contact per flat - whereas the 12 pt (at best) double that. I think it may be that under very heavy load the body of the socket twists a differnt way (just a guess as to why) YMMV ps I thnk a very good quality socket worth the investment here. Some of those cheapo things distort very easily. I have a 12 pt 21mm plug spanner - wish I could find somewhere that sells a 16mm one. Snapon would be ideal...

Think a bit harder about how it works :-) The second set of points on a 12 pt will be twisted away from the nut, so won't engage - they're behind the centre line of the bolt flat.

Now there are other 12 pt designs, eg those used in the halfords pro range (IIRC) where the points aren't actually at the edge, but instead set a bit in. But even for those, there are only 6 engaging at once.

Could your experience be because you've been comparing crappy 6 point ones to decent 12 point ones? Coz that would explain it.

cheers, clive

Gedore, facom, britool. But unless you find one on Ebay it's going to be over a fiver.

I was using a surface drive socket. This looks pretty much the same as normal 6 point socket, but the corners are rounded, so instead of the force mainly going onto the corners of whatever you're turning, the force goes onto the flats. The order things go in for least to most torque applied without rounding the bolt goes 12 point socket, 6 point socket, 6 point surface drive socket.

Or crappy 12 point sockets to 6 point ones, I've never rounded a bolt off with a Facom 12 point socket, I've burst 6 opint Elora sockets.

THE WHOLE EDGE

Wrong. They merely grip on the "points" - that's why a hex will beat a

12 point anytime. If you've had issues with hex sockets, may I suggest buying decent ones that are actually the size they state instead of being 0.5mm either way?