Was changing spark plugs a while back (Focus Mk2, 1.4) and noticed the second from left plug was tighter than the others. It didn't feel right so as there was no issues I just left the plug in. Now due to Covid I'm working from home and the car being off the road for a while wouldn't really affect me, so I had another go at lunch time there. It definitely feels tighter than it should be. I only turned it about a full turn but it's unnervingly tight. Squeaked a bit too. I can turn it and could stay turning it, but again I left it. I don't have the 'feel' that a mechanic would but it certainly feels wrong to me. In preparation I sprayed PlusGas around the plug for the last few days and I also tried the plug with the engine hot. 

So what do I do now? Is it a simply(!) a case of keep turning it to see if it does come out and then helicoil the damaged hole? An easy job without removing the head? What if the plug spins but doesn't come out? Wait for it to be blown out?

Any experiences or knowledge greatly appreciated. 

 

I know I could leave it in there but it will have to be changed at some stage. I'd like to have it changed. 

When you look down onto the cylinder head were the plug is does it look rusty, I had a similar problem when I came to change the plus in my old 1.6, its caused by rain or screenwash getting in there because these engines do not have a top cover. Took me several days by slacking the plug a bit each day and spray with WD40 each time, but i see your using Plusgas. It was just a matter of being patient and doing a little bit more slacking each day. After sorting it I bought the Volvo top cover that fits these engines and had no further problems with water getting in there.

 

Interesting that Eddie, thanks. Yeah I did have the screenwash/water issue when I got the car first but sealed around the washer jets. But there was a bit of water/dampness in there when I changed the other 3 plugs recently. And something tells me that that second spark plug is actually the one most affected by the screenwash/water issue?!

 

That's a very good point thanks and one I never thought of. Maybe it is just rust and not cross threaded. 

Tricky one, leave it or sort it. I have a motorbike, 1982 Suzuki gs550em. 4 cylinders. Bought in 1987 used until 1997. During that time I thought that one of the spark plugs was tight getting in. I thought best never touch that one unless I really need to. Twenty years later in 2017 I thought I’d get it going again. It proved troublesome. So I thought let’s take 3 plugs out, but I misremembered which one was the dodgy one, and snapped one off flush with head , so the centre electrode came out and left the hollow threaded part stuck in the head. Perhaps if I had tried to tackle it at the time it would not have snapped, instead of more than twenty yrs later. So how did I fix it. Got a junior hack saw blade in my electric jigsaw. Put down hollow bit of plug left in there. Saw into side very carefully. Then do same on the other side of hole, then tap top edge with screwdriver/ hammer to kind of squash it a bit to ease outward pressure, this loosened it enough so I could unscrew it. Can’t believe I managed to do it with little enough damage so it was ok with new plug in. Ps I couldn’t use normal jigsaw blade as too short to reach the spark plug hole.  Oh, I did use a magnet down hole to get the filings out as best I could, and then I checked with a camera down the hole, quite cheap on ebay, goes in usb socket on laptop. A long post but I don’t have much else to do. Hope this helps someone else reading this one day

I've read a few posts on the topic and some people have experienced very tight plugs (that didn't get any easier after a revolution or two) that came out with effort and didn't cause any damage. So I'll probably keep going and see what happens. I think the plan is that I'll do it with the engine cool which should hopefully give less chance of causing any damage.

I haven't changed lots of plugs in the past but it doesn't feel right. Just getting that down on paper so I can say to myself I told you so. 😂

If you're using a decent spark plug socket it should keep the thread central in the bore.  That's the idea anyway but yes, squeaky bum time as it comes out.

17 hours ago, isetta said:

and then I checked with a camera down the hole, quite cheap on ebay, goes in usb socket on laptop

You can also get ones that plug into your mobile phone, so no need to hunt down a Laptop if you do not own one

I do have one of those cameras for the laptop. Decent piece of kit for only £7 or so. 

I thought you could spray the plug with something which freezes it therefore shrinking it enough to loosen it from the block 

a good idea is to use a torque wrench.....   depending on how brave your are it should pull 60lb ft without snapping (but if its this tight all the way out I expect the head will have a fair bit of damage - might still be useable... )….but maybe stick to 40 lb ft if feeling scared, if it comes out at less the 30lb ft I expect its only dirt on the thread and it just needs cleaning. 

you could try with the engine HOT and the plus gas is a good idea -  because taper seat plugs can get very tight,  lots don't tighten up much, in this case lots of combustion gases can leak by and cause all the ***** your having over a few thousand miles.  If its this, I would expect the plus gas helps.  Another good idea with troublesome threads is to turn back and forth repeatedly as you wind it out.

get the crud out of the hole before undoing them, and ensure the seat is sparkly clean before ftting new plugs - I have never trashed a plug thread in 45 years undoing them or until the GS550 above, heard of one snap off

if you take it out and see the plug thread is heavily stressed the head will be a bit sad...  NOT recco but you could probably run a thread runner down the hole (use grease and much will come with it), and then crank out the crud.... cars are more resilient people think.  if the cars only worth 2k not much of a gamble... the other good idea will be to replace the plugs with iridium ones (see NGK on ebay) these last 40k miles no worries.  AND if you have the seat clean and the plug done up they will always come out by hand...    mines on 150k miles now and just swapped out a set of iridium plugs that were in there for 45k, almost looked like new...   plugs must be strong as you can easily get over 80 lbs ft to crack off taper seat plugs

3 hours ago, Botus said:

a good idea is to use a torque wrench.....   depending on how brave your are it should pull 60lb ft without snapping (but if its this tight all the way out I expect the head will have a fair bit of damage - might still be useable... )….but maybe stick to 40 lb ft if feeling scared, if it comes out at less the 30lb ft I expect its only dirt on the thread and it just needs cleaning. 

 

Well I went with that. I set the torque wrench to 35 foot lbs and it came out without 'making the noise'. 👍 A big bar gives you a lot of confidence! (which obviously causes plenty of issues too). I think the penetrating oil played it's part as it did seem a bit freer today. 

The top of the plug was in a poor state (and hopefully what was causing the very odd misfire and why it occasionally wouldn't start first time). Water is obviously still getting in. More crap than I'd like fell down into the cylinder but I used a pipe cleaner covered in grease to remove a lot of it. I also tapered the hoover pipe right down to a tiny tube which would fit down the plug hole and hopefully it sucked up anything left. Probably not 100% clean but hopefully nothing too damaging. 

I tried to clean the threads with the old plug and grease as best I could. The new plug went in over half way by hand but needed a small bit of leverage to get it down proper. I'm happy with it. 

 

Great bit of info in the above few posts so thank you all. I'll have to get that Volvo top cover that eddie mentioned. I was very aware of the water issue but wasn't available that these covers existed. What a shame Ford didn't provide them as standard. Would have saved a lot of issues for a lot of people! 

I know it’s out now but is it better hot or cold. When hot, which expands more the plug or the hole? Of course if plug expands more then it’s tighter when hot . Different metals expand by different percentage for same amount of heat. Does anyone know the answer? Might be useful to have it on here for people reading this with similar problem

There are more experienced guys here isetta but I read that it should be easier when hot but it's also easier to damage the threads. 

On ‎4‎/‎28‎/‎2020 at 6:19 PM, isetta said:

I know it’s out now but is it better hot or cold. When hot, which expands more the plug or the hole? Of course if plug expands more then it’s tighter when hot . Different metals expand by different percentage for same amount of heat. Does anyone know the answer? Might be useful to have it on here for people reading this with similar problem

aluminum expands much more than steel, plugs are steel, the head is aluminium.... but then I guess one might think the thread expands more... but I don't think so

torque wrench should be mandatory when removing modern glow plugs (again here when the engine is RED hot), and if you don't want the nightmare…. always change at max frequency of 60k miles - these are service parts NOT fit for life....

On ‎4‎/‎28‎/‎2020 at 6:12 PM, patja said:

 the very odd misfire and why it occasionally wouldn't start first time). Water is obviously still getting in.

its the washer jets.... silicone is a good idea (and I suspect still sensible even if you have the volvo cover)

I would swap the HT leads and the coil pack.   My local auto factor had everything for 60 quid and said they sell shed loads...  take the chassis number there are 3 different coils for 1.6 vvti mk2 !!!   once the leads have been in that water bath, it puts mega stress on the leads so they just start sending the spark anywhere but the plug electrodes