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

I sometimes wonder why i try doing preventative maintenance!

So I did a full service on the Plus 4 (duratec engine) for the first time since a full dealer service, I took out the spark plugs to check the state of them and the gaps.

I was very careful refitting them - conscious of not cross threading etc. However, number 2 plug does not "nip up". It carries on turning with just under 10Nm of torque. I tried comparing the number of turns with the other plugs, did that to the number 2, then went perhaps 3/4 turn further with this steady, but slightly low torque. I dare not go further. I have looked down the hole and cannot see any swarf on the piston or sides of the hole. The plug seems ok. I cleaned the threads with a cloth on a stick - nothing untoward.

When I first got the car (from a far away dealer), it failed on my first journey and went to my local dealer who found the plugs swimming in water and corroded. So my theory is that the threads were slightly damaged when the number 2 plus was extracted then.

So what to do? I can leave it torqued up to the just under 10Nm and hope. After all it has been to Angouleme and back twice like that. I have a home made engine cover which should take the impact if it pops out. Or perhaps take it somewhere for a helicoil fitment. What's the wisdom of the forum on this?


Cheers
Nick

This is a difficult one. I dont think a helicoil can be fitted without removing the head -- still I suppose one has plenty of time to do this at the moment. It might be ok for another 10k miles but I would be worried about running it as is and it will haveto be done some time. I know it's too late to help your problem but I always remove the plugs as soon as I get any car (new or used), lubricate the plug threads with ultra high temp ceramic grease (some people use Coppersip) and refit them. It's so easy to damage alloy heads, particularly with the very narrow bodies of some modern spark plugs. You might be able to fit the helicoil with the head in place and suck the swarf from the combustion chamber with a pipe on a Hoover but I've never done it. On another matter I'm signed up for the Remparts this Sept but God knows if it will go ahead.

Nick

As Griffo says, this is a really tough one. I don't know the Duratec engine well so my comments are based only on generalities.

To be 100% certain you need to investigate this further. I don't know if you have access to an endoscope, but that might be able to look at the threads more closely and ascertain if it does require a helicoil.

Can you remember if the number 2 plug came out with less effort than the others? If so it might have sitting "loose" in the thread , but I doubt this. I suspect it was reasonably well seated, but disturbed when removed.

In the end , to be sure, I think you are going to have to bite the bullet and take the head off.

Good luck

A mechanic pal of mine reckons it's fine to helicoil a plug without removing the head, so long as you make sure the valves on that cylinder are closed and on no account drop the broken-off tang when you remove it. He reckons he's done it on loads of cars without a problem.

Does not sound good...sorry.

I have no idea of the plug type whether it has a washer of a chamfered shoulder, for the type with a washer I was taught to screw them in by hand until I felt they had hit "bottom" then give a quarter turn to compress the washer.

With the shouldered type again the idea was to feel the thread starting correctly and screwing in by hand you would feel if it had perhaps started incorrectly thus less chance of using force to cause things to cross thread... once the plug felt on it`s seat then torque to the required setting..

In theory you should be able fit a helicoil with the head on but you will need to consider the access to the job to ensure the old threads are drilled out properly, the oversize tap is started correctly etc.

Also, the taps in helicoil sets tend to have straight flutes rather than spiral flutes, which will tend to allow the swarf to drop down the bore irrespective of whether the valves are closed.

Have you done a compression test on the affected bore to check for leakage past the damaged threads?


Arwyn

I would get it helicoiled. Good Luck.

Apparently the reason you make sure the valves are closed is to ensure any ally swarf doesn't get out down the exhaust port and bugger up the cat.

I've only ever done it by removing the head and it was a very straightforward job so personally I don't think it's worth the risk.

OK thanks for the advice folks...
This is not something I shall attempt at home.

We have a couple of local engine specialists - Scholar Engines and Dunnell Engines - both have Duratec experience - so I will talk to them when the lockdown is over.

Thanks,
Nick

PS On Friday I shall be hopefully changing one brake slave cylinder - I have a back brake that does not back off so binds slightly and I suspect a corroded cylinder..... No doubt I'll bugger up something else and be on here later!!!!!!!!!!

Well Nick, there's no better time to be off the road, and if I were you, once you've done one rear brake cylinder, the other side will be much easier...……..