Morris Minor Owners Club

Over the years I have accumulated quite a few fouled spark plugs none of which is anywhere near worn out. As the spark plugs for our engines are quite cheap, I have typically replaced a set with new ones and kept the old ones "to clean up on a rainy day". Well that rainy day finally arrived and I thought I would try something different from the usual spark plug brush and carburettor cleaner.

I cleaned the plugs in my ultrasonic cleaner in a hot solution of caustic drain cleaner. The results are very good. All of the caked on carbon has gone as well as all of the oil contamination. Sodium hydroxide is used as an oven cleaner for the same reasons. After cleaning the plugs are thoroughly rinsed in clean water and dried. I now have years worth of spark plugs!

Of course, in an ideal world the plugs would not get badly fouled, but my engine has been burning oil for a long time. It is now being rebuilt so this problem should be a thing of the past.

Stephen

Well done, the ultimate recycling,
I considered myself to be a saver, they might come in one day.
Regards Win

I bought an ultrasonic cleaner and got some great results with cleaning up two carbs. I would be a bit reluctant to submerge spark plugs but they certainly look clean. Have you put any back in the car to test or will you wait until the engine is done?

I recall the engineering God Alan Millyard once saying never clean a plug with a brush just use a blow torch.

rocco wrote: ↑Tue Feb 04, 2025 6:49 am I bought an ultrasonic cleaner and got some great results with cleaning up two carbs. I would be a bit reluctant to submerge spark plugs but they certainly look clean. Have you put any back in the car to test or will you wait until the engine is done?

As yet I have been unable to test as I have no engine at the moment!

Stephen

Wes wrote: ↑Tue Feb 04, 2025 7:32 am I recall the engineering God Alan Millyard once saying never clean a plug with a brush just use a blow torch.

That's because people would use a wire brush and then get a broken strand of wire bristle caught up in the air gap...

geoberni wrote: ↑Tue Feb 04, 2025 10:51 am

Wes wrote: ↑Tue Feb 04, 2025 7:32 am I recall the engineering God Alan Millyard once saying never clean a plug with a brush just use a blow torch.

That's because people would use a wire brush and then get a broken strand of wire bristle caught up in the air gap...

Yes but also because abrasives cause a rough surface that is easier for further deposits to stick to. This is after all why we scuff surfaces to get paint to stick......

Stephen

Is a copper brush for suede shoes softer than the metal of the electrodes?

A brass spark plug brush is softer than the steel but if they're copper-core plugs and it's pure copper than I would have thought that would be softer than the brass? I am not sure but I have never noticed damage from using a brass brush. We can be thankful that our spark plugs are cheap. My modern Audi uses some exotic platinum alloy-core plugs and they are extremely expensive!

Stephen

OK, thank you. TBH I'm not sure if my little shoe brush is brass or copper, but it is soft. I don't think I can add any more other than I have used them for decades, apparently* without issue. I haven't got an ultrasonic cleaner.....
* I say 'apparently' because I can't be sure that my plugs might have gone on longer using some other method. But they do go on for years....

I’m a huge fan of Ovenpride oven cleaner for cleaning spark plugs. My Godson used to get through iridium NGK spark plugs in his Rotax kart at a rate of two per weekend. At £11 each this was not sustainable. A jam jar half full of Ovenpride for 24hrs would have them clean. A quick rinse and blow dry and they were good to go again.

The same method has worked really well with iridium and standard NGK plugs in my 1275 Midget. Just be careful not to leave them in too long as the Ovenpride will eat the metal eventually.

Yes the same idea, Sodium Hydroxide. Strong alkali.

Stephen