Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Duratec spark plug - hmm

Chances are the threads are knackered.
However, as it has probably to be repaired anyway at some expense, why not give it another go? Trouble is, you can never be sure exactly when the thread takes, up so comparing turns with another plug may not be a reliable yardstick. I suggest giving it a bit more than the three quarter extra turn just in case its a tight spot that may eventually come right with a couple more turns or it will strip the thread properly. Nothing lost. This might be described as a Sh*t or bust approach but has a slim chance you may succeed.

Its a thought. The spark plugs are those with a tapered seat (not a washer), and the tapered seat is not in contact - i put some copper grease on to see if it was wiped off and it wasn't.

Hmm - if I feel brave I'll have another go.

And Dave - yes I will do the other side but I can't get a replacement yet... so I shall do the bad side first.

Cheers
Nick

Is it worth getting another plug before you go he helicoil route. It might be off spec

This was my first thought, to try fitting a plug that you know torques down correctly?

Well emboldened by Doug's comment I've just given it another go. I checked No 1 with copper grease on the seat area to see if it seated - which it does.
Then again on No 2 and it didn't. So I tried oiling the thread and running it in an out a few times, each time seeing if it seated (it didnt). So I carried on turning for a bit longer and it did tighten. So I pulled it out and put it back again and it tightened better. Still not a satisfying "nipping up" instant tightness, but it is more torqued than before.

Good thought John - I have the old plugs so I could try one of those back in again.

I am more content now though!

Nick

One of these might help:

Thread restorer

Interesting tool. Well I've just tried an older spark plug (cleaned up), and it does the same -it will torque up but not a crisply as they others. And It does need some winding in for the last couple of turns using the ratchet bar (whereas the others are turn by hand then nip up, in the usual way). So maybe I do have some messed up threads towards the bottom.

It has, however, led me to look at the old damaged plugs more carefully... and it does seem that apart from one cylinder the originals did not naturally seat - the plugs that were damaged by the water sitting in the wells have corroded seats - which is odd.

Pleased to hear that result Nick and you have been very methodical. Bear in mind that these tapered plugs don’t need to be overtight...14 lb. ft or 20 Nm is plenty but expect you know that anyway. Good luck with brake cylinders.

It could be that if the plugs had not been seating fully before, there may have been a bit of carbon build up in the lower thread or two so you might just be "chasing'" the carbon out of the thread and in effect restoring them.

Hello.. I had a similar problem as you have with a sticky rear brake cylinder. Have a look at the Gomog manual under brakes (4:14) sticking brake problem. It worked on my car. I marked about .5 mm on the rod and filed to the mark.
Hope this helps you out.
Best of luck with your plug problem.