HT Leads and spark plugs.. for the love of god!

Drone31

I'm not sure of a better place to ask this to be honest, but I'm always up for saving a few quid and having a go at pretty much anything when it comes to my car - and recently I've decided to change my spark plugs as they were looking a bit worn and the worse for wear. A simple job I have done a hundred times before - however I noted when I checked them yesterday, that the furthest left HT Lead (the longest) was difficult to put back on.

I changed them all today - and the lead will simply not go back on the plug. I tried one of the other leads just to see if it was that specific one, but nope - it won't fit.

If I remove the plug, it's fine, fits no bother. What on earth could be causing it? There doesn't appear to be anything blocking the lead fitting back on the head of the plug. It's driving me mad! Any thoughts on what might be causing it? It can't be the lead as the others have the same issue, and they all fit the plug fine when it's removed. Argh! :think:

Hasbeen

Can you give car model year etc?

And confirm lead fixed onto old plug ok but now does not attach to new plug.

Difference in plugs? have you tried putting original back in and trying it as rule out method?

Drone31

Hi there, it's a Ford Mondeo 1.8lx Duratec HE 2001

Fixed to old plug ok... however, yesterday was the first time I'd removed them myself on this particular car, and I had to put them back in to head to the motor parts place - I had difficulty getting it back on then, to the old plug (just that one), but it went eventually. It's a no go at all on the new one though.

It was a set of 4, they're the same plugs as were already in. Before I fitted them all I plugged them into their respective leads; as I say, it fits like a glove, like the others when removed, but it's just this one that I can't attach the lead to when it's fitted in place.

My usual suspicion would be that it must be the lead... I suppose one thing I could do, would be to try one of the other new plugs in that spot and see if I have the same bother. They're all identical though; and it fits when it's out. Is there anything that could obstruct it? As I say I couldn't see anything but that was in natural light; I didn't shine a torch in for a proper look but it seemed all clear.

forgotmyname

Are the new plugs shorter than the old ones?

Have you pushed the metal clip thats inside the rubber further up?

When you try and fit the lead it bottoms out before the metal clip attaches.

Drone31

forgotmyname wrote: »

Are the new plugs shorter than the old ones?

Have you pushed the metal clip thats inside the rubber further up?

When you try and fit the lead it bottoms out before the metal clip attaches.

Plugs are dead on the same length; I wondered the same about the clip but none of the other leads will go over it either when it's fixed in - yet they fit over their respective plugs no problem. I suppose the more I think about it the more likely it's something obstructing it. What that could be I have no idea, but the issue was there before I owned the car it would seem.

I think I will swap a couple of the new plugs around just in case, but I'm prepared to bet it won't make any difference.

Do any of you know if there's any danger in trimming the rubber on the lead back so it's a closer fit?

forgotmyname

Trim as little as possible. The more exposed the easier it is for the spark to track.

Old cars never used to have full shrouding of the plugs. They ran fine.

Well until they got damp/wet of course

cheekychappy

Have you cross threaded the spark plug and the HT lead is hitting the sleeve of the cylinder head?

Norman_Castle

Is the plug washer missing?. Loosen the plug a bit and see if the cap fits then. Does this cap fit on the other plugs?.

mkirkby

Is there anything down the hole nestling next to the spark plug?

maninthestreet

Can you upload a few pics of the offending spark plug in situ, and the plug recess in the cylinder head with the plug removed?

Drone31

cheekychappy wrote: »

Have you cross threaded the spark plug and the HT lead is hitting the sleeve of the cylinder head?

That's crossed my mind - it was like that before I fitted the new plug, but I may have made it worse. There doesn't seem to be even space around the plug when I stick a finger in, but that might just be my imagination - if that is the case, is there anything I can do?