Morris Minor Owners Club

If the plug is running hot use a cooler running plug for example if using a N9Y replace with a N7Y or similar. The lower the number the colder the plug runs. Use a plug without a extended nose.

https://www.sparkplugs.com/what-is-a-sp ... at-range-2

The title of this topic reminded me of an owners manual for a British Seagull outboard motor. Those motors were pretty well indestructible but definitely "had their moments". Anyway, the manual advised that in cold weather, the spark plug should be warmed in an oven to aid starting. Given that the motors were often used on the back of a dinghy, I often wondered just where one was supposed to find an oven, and just what reaction a chap would get when explaining to his wife that he was just heating an oily spark plug in her baking appliance Hopefully that isn't too sexist for today's readers.

When I replaced the starter ring on my Renault 5 I heated it up in the oven to expand it in order to fit it ! I have also heated spark plugs on the Rayburn for my ailing two stroke garden impliments.

I recently fitted 4 new plugs in my rebuild 1275 engine. I've driven 500 miles or so and wanted to check it all over. When I started to remove 1 plug to check colour, it snapped. Then I tried another plug, snapped. 2 out of 4 broke.

Me thinking it was my plug spanner, I tried it on my spare engine with old plugs in. All 4 came out easy. I'm thinking 2 things.

Plugs do run hotter or the quality is very poor now on parts. Plugs were from ESM.

Regardless of the supplier, which manufacturer is stamped on the plugs?

ampwhu wrote: ↑Sat Sep 04, 2021 9:49 am I recently fitted 4 new plugs in my rebuild 1275 engine. I've driven 500 miles or so and wanted to check it all over. When I started to remove 1 plug to check colour, it snapped. Then I tried another plug, snapped. 2 out of 4 broke.

Me thinking it was my plug spanner, I tried it on my spare engine with old plugs in. All 4 came out easy. I'm thinking 2 things.

Plugs do run hotter or the quality is very poor now on parts. Plugs were from ESM.

Where did they break? Ceramic or Metal parts?
A correctly fitted Plug Spanner/Socket is only bearing on the metal 'nut' of the Plug, it should not be exerting any pressure on the ceramic, the most it should be doing is having a foam padding to help lift the plug out.

If the 'nut' part separated from the 'thread' part, then it's a quality issue after 500 miles so complain to the manufacturer.

Look at this video of a Yank who broke 2 plugs on a Pick-up.
His must've been in there since the truck was made looking at the rust....
https://www.youtube.com/watch?v=JijVI3RTkMY

ceramic part. Plugs were Champions.

Interesting comment from geoberni , could it be the plug spanner catching on the plug as its removed and breaking the ceramic ????

i agree totally. But these plugs were very brittle which is why they broke easily. First time for me in what.... 35yrs!

My champions snapped on 3 of my ceramics, this with me not catching them with my socket.
I think unfortunately the quality isn't as it used to be on some plugs, I have fitted NGK with no issues so far.