Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Spark Plugs changeout Mazda MZR/Duratec engine

OK, so i know they now last 60K but my cars 7 years old and i've heard they can be impossible to remove so i thought i would remove and renew. I sourced new plugs (NGK) from Opie oils at £54 quid.
I partially screwed out each old plug and and blew out the well with my tyre inflator air compressor, a lot of debris and dust was emitted from the well that would have ended up in the cylinders so i would recommend this procedure!
Upon removal the plugs were found to be the original FOMOCO fitment, nothing wrong with that i would suggest but i like NGK. The plugs that i removed were heavily corroded around the hex section and a rust tidemark confirmed that water submersion had occurred. My engine is an OMEX as fitted to +4SS so maybe its the type of HT terminal thats used , i must stress it never missed a beat!!, maybe the normal 2.0 litre duratec coil at plug is more water proof and would not suffer the same corrosion issue, worth checking

P.S. the plug tips were still in great shape, really no need to change, but hey after 7 years service (only 18k) why not

That advice could save someone an engine rebuild ..

Excellent information Lowflyer

Hi Kev, is the almond making an appearance at Hurworth, near darlington next sunday? (13th). Nice little run from york, see hurworth community association classic car show

Did you put any form of anti seize lubricant on the threads of new plugs before you replaced them?

Arwyn

There was a 4/4 with a 1.8 Duratec in my local garage a little while back with a seized plug. I tend to just slacken and re-tighten mine every now and again. Only takes minutes. I use anti seize too.

Antiseize had already been applied previously i must say i always use it, however NGK recommend that you do not use it due to the inaccuracy of the torque setting if used. For me its a must, same with wheel bolts.....never lost a wheel in 53 years!!

This highlights the need of a cover of some sort to exclude rainwater from the sparkplug well. For the life of me I don't know why Morgan don't offer one as an option. Much as the louvres look the part I wonder if it would not be better to have the louvres only on the sides and at over the air intake for the heater/aircon.

This has always been a bit a conundrum for me as I have exactly that louver configuration. No louvers over the engine but I do suffer with corroded plugs. Obviously louvers might let water into the engine bay but I don’t buy into the mainstream belief that they are responsible for corroded plugs. Many Fords suffer with corroded plugs too and they don’t have louvers either and often have clever designed engine covers.

The water sealing around the cam cover and plugs lead is really very good on my engine. The plug caps have a super tight triple finger environmental seal and there is a 10mm high up standing on the cam cover around the plug cavity. There would have to be quite a deep puddle of water sloshing around to breach that!

One of my corroded plugs despite no louvers
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My money is on high humidity noxious internal combustion gases getting past the cam cover seals and causing condensation to form on the plug surface which causes the corrosion. Perhaps on a cold day when an engine block cools after a run the plugs on top would tend to attract surface condensation from the high humidity cooler atmosphere trapped around the plugs?

Here is a pic of the underside of a Duratec cam cover (not mine).


You can see the seal paths around the plug chambers where the cover seals to the head. Whilst this type of simple seal in a plastic housing would prevent the non-pressurised engine oil escaping it would not take much of a pressure differential for gases to escape into the plug cavity.

Just a theory………