Talk Morgan Forums Thread Like Summary - Seized spark plug

Hi everyone!
Having a maintenance blitz on my 1984 +4 (Fiat engine) Mog. Decided to remove and check the spark plugs, only to discover that one has seized and won’t unscrew. I haven’t forced it as I don’t want it to break off, which could be an expensive top end removal!
Has anyone got any useful tips please?
Many thanks Smuggs.

We used to make steel for spark plugs. Thousands of tons a year. Also used for other end use.
It is a low carbon steel, similar to EN1A spec.
0.1%carbon so at the lowest mild steel spec. It was also a resulphurised steel as rhe sulphur content helped with machining. A bit of extra manganese to combine with the sulphur and help in oxygen control , everything else at low levels. It was not easy to make as whhen you go that low in carbon content in the molten bath of metal the oxygen level shot up and there was a danger of ending up with ingots like Aero bars, full of holes that would self weld inside but those at th3 surface split open to leave a useless finish. When ready to tap the furnace a " block" was put in with so that refinement was stopped for long enough to tap into a ladle. The block was a deoxidiser to "kill" the reaction temporarily. Tapped a5 1600 degC. Rolled to billets and sent to a finishing mill in the Birmingham area where it would be rolled to hexagon shaped feedstock to high speed maching units.
We'd also add lead shot during casting as the lead helped lubricate during high speed machining.
We started with open hearth furnaces and moved to two 150tonne electric arc furnaces. From an art to brute forde!
Great memories of those days.

This, and make sure you use a correctly-sized 6-point socket. Also a nice long breaker bar if you can, it's a lot easier to apply gentle but increasing amounts of torque using a long bar gently tan it is heaving away on a short ratchet handle.

I know that opinions vary on this, but on spark plugs in older engines that are vulnerable to water ingress I use a tiny smear of Copaslip on the upper part of the threads to prevent seizing. Others will say you shouldn't do this as the copper grease will melt migrate down the threads and contaminate the combustion chamber but it's never happened to me because I don't splurge the stuff all over the place.

A few years ago I successfully removed a tight spark plug using a spray called Arctic Hayes Crack-it shock release spray.

Used by plumbers and available at Screwfix, it cools the plug which then shrinks to permit release.

One of the first engines I worked on around the age of fourteen was an old side valve that had been out in the rain for a while leaving rusty spark plugs wells. Managed to remove three plugs but the fourth wouldn't budge. On a whim poured vinegar into well and left overnight. Couldn't believe how easily it came out the following day.

Vinegar is under-rated. During my two year restoration of my MGBV8, I wanted to use as many small components and clips as possible. Most were grubby and tarnished, but a few days in a container brought most things up like new, including nuts and bolts. It leaves a matt finish, which can be polished up easily.

Vaseline is the other "V" which is overlooked. The ONLY thing which has stopped my sidescreens misting up. All the fancy polishes and anti-foggers made no real difference. Vaseline stops it, and now I also use it on chrome plated stuff, It polishes of like polish but leaves a resistant layer for damp air.