1.8 Stripped Spark plugs help

[Garfy81]

Morning everyone.

Just after some advice please regarding the ZT-T I purchased September. It’s a standard 1.8 none turbo. Whilst driving, the car has now developed what I can only describe as an intermittent misfire. I changed the leads and coil packs and seemed better but does come and go which is puzzling.

I decided a plug change was needed and when I went to remove the plugs, the first one (as looking at the engine, plug on the left nearest drivers side) was very loose and just spinning. The next one along was ok to come out, the 3rd is the same just spinning and the last one came out ok.

From looking at the 2 that come out, the plugs look newish and no obvious issues. When looking with a touch at the two which won’t come out, they look older plugs from what I can see.

I have contacted a local engine centre to where I live and they have quoted £1,230 to remove the head, helicoil and put back on.

So my questions for advise please are

1) has anyone ever had any issue like this before that they have managed to resolve without removing the head.
2) If I am to have the head removed, is helicoil the way to go or should I look to purchase a good/new head

Whilst I don’t have the cash at the moment to have the car done, I intend to not give up on the car as since owning it, I have grown fond of her. Whilst I’m no mechanic, I do have some albeit limited knowledge and if the head has to come off, then I intend to do this myself in the new year. Any advise of removing the head (do’s and Dont’s ) would be greatly appreciated. I will with the head off fit all new gaskets, water pump, belts etc.

Many thanks everyone for any help/ advice you can give and also merry Christmas.

Matt 👍

[Matt_75]

If you can get the spinning plugs out somehow with the head in situ, I have seen a video of spark plug thread repair before albeit on a V12 BMW: https://youtu.be/zN-EO_WivXY

This isn't the proper way of doing it and he does mention this in the video, but has some methods of reducing the risk of engine damage from metal shavings.

If you decide to do it properly (removing the head), make sure to use a workshop manual and follow the correct sequence for removing the bolts. There's a copy of the manual here (post #8, service proceedures document): https://the75andztclub.co.uk/forum/s....php?p=2604687

[suzublu]

May I also add, when, if, you get the plugs out and refit, gap them to .75/.8mm👍

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[alan richard]

My sympathies.

I have in the past had similar on a motorbike that blew one plug out.
A local guy was able to helicoil it in place.

We stuffed a clean but grease covered rag down the plug hole first before starting to catch any swarf and fished it out after.

It worked out ok.

-A

[macafee2]

Helicoiling has been around for many years and is a tried and tested method.

Ideally, remove the head.
If your head is good apart from the stripped thread I would tend to stick with it.
If you do helicoil with the head in place there is a risk of swarf but this can be minimised and you may be fine. If you are willing to spend over a £1,000 on the car you have nowt to loose by doing a helicoil in place. Try to get as much swarf out as you can.

good luck

Is the head that difficult to remove as £1,230 seems a lot of money

macafee2

[Popcorn]

Originally Posted by suzublu

May I also add, when, if, you get the plugs out and refit, gap them to 7.5/8mm👍

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Just a guess but should that be 0.75/0.8mm

[suzublu]

Originally Posted by Popcorn

Just a guess but should that be 0.75/0.8mm

Oops 😁 yes of course 👍

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[SCP440]

Originally Posted by macafee2

Helicoiling has been around for many years and is a tried and tested method.

Ideally, remove the head.


Is the head that difficult to remove as £1,230 seems a lot of money

macafee2

That is they dont want to do it price and if they do end up with the job that is enough to make sure they are happy with it.

[Mr Toad]

Hi Matt,

About 16 months ago my Mustang engined Rover 75 V8 had a spark plug exit the engine and damaged the threads in the head. Apparently this is a very common problem with Mustang engines and their derivatives in the USA. Helicoils are not considered permanent repairs. The best kit is an American one but it is expensive.I used a kit made by Sealey Tools VS301 together with Sealey's high strength thread adhesive.

There are two problems. Firstly, you need to try and get the swarf out of the cylinder when cutting the new thread. I modified a vacuum cleaner pipe with a piece of neoprene tubing that I could put down the cylinder. I also greased the taps and then removed the swarf with brake cleaner, When the job was completed and before I put the plug back in I ran the engine briefly to eject any remaining swarf.

Secondly, the American kit has a guide which you insert into the cylinder to ensure that the new thread is not cross threaded. The Sealey kit does not have this useful tool so that when cutting the new threads you have to be very very careful and take your time.

There is a useful video on Sealey's internet site.

16 months on the new thread is holding so it seems to have done the trick. Most importantly it can be done without removing the head which in my case would have been a mission.

Good Luck
Martin

[Mike Noc]

Originally Posted by Mr Toad

Helicoils are not considered permanent repairs.

Not only are they permanent repairs, they are stronger than the original threads in aluminium heads.