classic car forum header
Classic cars forum & vehicle restoration.
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
Register     Posting Photographs     Privacy     F/book OCC Facebook     OCC on Patreon

Part stripped spark plug thread ..alloy head
Goto page 1, 2  Next
Post new topic   Reply to topic    Classic cars forum & vehicle restoration. Forum Index -> Mechanical Restoration
Author Message
ukdave2002



Joined: 23 Nov 2007
Posts: 4100
Location: South Cheshire

PostPosted: Sat Mar 15, 2014 7:33 pm    Post subject: Part stripped spark plug thread ..alloy head Reply with quote

Bugger Mad

I must have removed and reinserted spark plugs in the Stag more times than .....well I have done it a lot ! Smile

Today whilst bringing the Stag out of winter hibernation I removed all the plugs to check and clean. All was well apart from putting the plug back in number 4 cylinder, actually one one the easier cylinders to access the plugs.

I always screw the plugs in with thumb and forefinger , only using a wrench for the final tightening ......No 4 plug did not want to go back Sad , the thread on the plug was clean and fine after 10 mins of trying to fit it , I decided to run a plug tap through the thread, thinking it may just need cleaning up.
The tap also took some persuading , but did take , but only for a turn and a half , then it went stiff Confused What do I do back out or carry on?....I backed out a few times, but then decided it was all or nothing, and ran the tap with what I would describe as medium force.

So I can now insert the plug , but with only half the turns it should have, the plug seals and the engine runs fine, so what are my options;

Leave as is until there is a future problem
Put a helicoil in now, it's one of the easier cylinder to do Smile
Never change plug 4 again !

Advice welcome Smile

Cheers

Dave
Back to top
View user's profile Send private message Visit poster's website
kevin2306



Joined: 01 Jul 2013
Posts: 1359
Location: nr Llangollen, north wales

PostPosted: Sat Mar 15, 2014 8:06 pm    Post subject: Reply with quote

Id leave it and see how it goes, maybe a smear of copperslip on the thread to ease it a little?

Kev
Back to top
View user's profile Send private message
Rick
Site Admin


Joined: 27 Apr 2005
Posts: 22429
Location: UK

PostPosted: Sat Mar 15, 2014 9:38 pm    Post subject: Reply with quote

Technically it may not be the correct solution, but as Kev suggests I'd leave it alone, for now at least, and see how it goes on a few local-ish jaunts.

RJ
_________________
Rick - Admin
Home:https://www.oldclassiccar.co.uk
Videos:https://www.youtube.com/user/oldclassiccarRJ/videos
OCC & classic car merchandise (Austin, Ford ++):
https://www.redbubble.com/people/OldClassicCar/shop
Back to top
View user's profile Send private message
Phil - Nottingham



Joined: 01 Jan 2008
Posts: 1252
Location: Nottingham

PostPosted: Sat Mar 15, 2014 11:27 pm    Post subject: Reply with quote

Been there done that and everything correct to the book and I also agree with what has been said ie leave it well alone.

You have nothing to loose - remove it only when you have to - then use an old plug as thread chaser to clean out the threads - this has worked for me twice now without problems and both are still OK after 10+ years

NEVER EVER remove/replace plugs when an alloy head is even remotely warm leave 24hours min. Use thread lube to replace and quarter turn MAX.

I did loose a plug on on my P5B V8 because of under tightening

Embarassed and often find them then "loosish"
_________________
Rover P2
Rover P4
Rover P5 & P5B
Land Rover S2 & S3
Morris Mini Traveller Mk2
Back to top
View user's profile Send private message Send e-mail
ajlelectronics



Joined: 04 Oct 2010
Posts: 168
Location: Gloucester

PostPosted: Sun Mar 16, 2014 8:34 pm    Post subject: Reply with quote

Phil - Nottingham wrote:

I did loose a plug on on my P5B V8 because of under tightening


Well you would.
_________________
Evans Waterless Coolants
Find this and more at http://www.classicmicrocars.com
Sat TV / Aerial systems etc: http://www.ajlelectronics.co.uk
Back to top
View user's profile Send private message Visit poster's website
goneps



Joined: 18 Jun 2013
Posts: 601
Location: Auckland, New Zealand

PostPosted: Mon Mar 17, 2014 1:11 am    Post subject: Reply with quote

Dave,

I presume these are alloy heads? If so, when you next have to remove that plug the best answer is to Helicoil it, and if I were in your shoes I'd bite the bullet and do the whole lot as an insurance for the future.

If Triumph hadn't been so cheap-skate they'd have used steel inserts in the first place. Fine threads (M14 x 1.25 if they're standard plugs) are not suitable for soft materials! My 1964 BMW motorcycle had steel plug inserts in its alloy heads, and there was never a problem in the 36 years I owned it.

Richard
Back to top
View user's profile Send private message
peter scott



Joined: 18 Dec 2007
Posts: 7113
Location: Edinburgh

PostPosted: Wed Mar 19, 2014 5:37 pm    Post subject: Reply with quote

I'd be inclined to fit a Helicoil now otherwise you might end up with an emergency repair instead of one at your leisure.

Peter
_________________
http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon
Back to top
View user's profile Send private message Visit poster's website
D4B



Joined: 28 Dec 2010
Posts: 2083
Location: Hampshire UK

PostPosted: Wed Mar 19, 2014 5:44 pm    Post subject: Reply with quote

How do you prevent swarf getting in the cylinder when helicoiling?

or is it only to be done with head off?
Back to top
View user's profile Send private message
goneps



Joined: 18 Jun 2013
Posts: 601
Location: Auckland, New Zealand

PostPosted: Wed Mar 19, 2014 10:41 pm    Post subject: Reply with quote

Safest to remove the head(s), of course, but in dire circumstances a liberal coating of grease on the tap will retain virtually all of the swarf. Ditto for snapping off the tang of the Helicoil.
Back to top
View user's profile Send private message
ukdave2002



Joined: 23 Nov 2007
Posts: 4100
Location: South Cheshire

PostPosted: Sat Mar 22, 2014 8:02 pm    Post subject: Reply with quote

Thanks for the replies Smile

I'm going to see how it goes! Logic being that the worst that can happen its that I may loose 1 out of 8 cylinders, so would probably be able to limp home Smile

I have fitted inserts before with the head in situ, doing as Richard suggested greasing the drill and tap, but also making sure that the inlet valve is open with a plate on the carb, tapped to take an airline fitting so that compressed air can be blown in, encouraging swaf to stay out of the cylinder, + it's an aluminium head so whilst any contamination in the cylinder is not desirable, it's softer than the rings and cylinder walls.

Will keep you posted

Dave
Back to top
View user's profile Send private message Visit poster's website
winchman



Joined: 21 Feb 2014
Posts: 235
Location: Merseyside

PostPosted: Tue Apr 01, 2014 11:15 am    Post subject: Reply with quote

I have used a Dyson with a straw taped to the end of the hose, it works well.
_________________
It will come in handy even if you never use it.
Back to top
View user's profile Send private message
Rosco663



Joined: 17 Dec 2012
Posts: 257
Location: South Australia

PostPosted: Sun Apr 06, 2014 2:28 am    Post subject: Reply with quote

ukdave2002 wrote:
..........making sure that the inlet valve is open with a plate on the carb, tapped to take an airline fitting so that compressed air can be blown in, encouraging swaf to stay out of the cylinder,......


Excellent idea Idea
_________________
Rosco
Back to top
View user's profile Send private message
Greeney in France



Joined: 06 Mar 2008
Posts: 1173
Location: Limousin area of France

PostPosted: Sun Apr 06, 2014 9:01 am    Post subject: Reply with quote

I dont know if it past this but I have a couple of different sizes of these and they work really well.
You put then in, find the inner threads and then expand them to unthread.

_________________
www.OldFrenchCars.com

We do these things not to escape life but to prevent life escaping us
Back to top
View user's profile Send private message Send e-mail
Jonv8



Joined: 28 Jan 2009
Posts: 66

PostPosted: Thu May 01, 2014 6:24 pm    Post subject: Reply with quote

Greeney in France wrote:
I dont know if it past this but I have a couple of different sizes of these and they work really well.
You put then in, find the inner threads and then expand them to unthread.

That is a tool I've been trying to design in my head for ages....
Who makes them ?
Back to top
View user's profile Send private message
Greeney in France



Joined: 06 Mar 2008
Posts: 1173
Location: Limousin area of France

PostPosted: Thu May 01, 2014 6:27 pm    Post subject: Reply with quote

Its a Sealey MS003
_________________
www.OldFrenchCars.com

We do these things not to escape life but to prevent life escaping us
Back to top
View user's profile Send private message Send e-mail
Display posts from previous:   
Post new topic   Reply to topic    Classic cars forum & vehicle restoration. Forum Index -> Mechanical Restoration All times are GMT + 1 Hour
Goto page 1, 2  Next
Page 1 of 2

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
OCC Merch link
Forum T&C


php BB powered © php BB Grp.