Cracked cylinder head
#1
Scooby Regular
Thread Starter
iTrader: (1)
Join Date: Jul 2012
Location: Scotland
Posts: 102
Likes: 0
Received 0 Likes
on
0 Posts
Cracked cylinder head
Have just removed head on my 03 wrx wagon to replace head gasket and have noticed both heads have cracks around spark plugs ,
Has any one else had this problem and will they be ok to use again or should I find some new ones ?
Has any one else had this problem and will they be ok to use again or should I find some new ones ?
#5
mine was a lot more cracked, but i only found out at rebuild time, and i didn't rebuild due to a failure, car was still running good. I have been told that these are common. I got another set though
Wrong torque setting on plugs can cause this and too much heat - but if you ask me it is the material itself which is not the best.
Wrong torque setting on plugs can cause this and too much heat - but if you ask me it is the material itself which is not the best.
Trending Topics
#8
Scooby Regular
iTrader: (23)
Join Date: Jul 2008
Location: In the fast lane
Posts: 3,458
Likes: 0
Received 0 Likes
on
0 Posts
These cracks are very common, but that crack looks very close to the valve seat, although it could just be the camera angle.
If the crack goes more than 5 or 6 threads deep into the plug hole it will be getting close to the water jacket.
If the crack goes more than 5 or 6 threads deep into the plug hole it will be getting close to the water jacket.
#9
Scooby Regular
iTrader: (1)
The cracks are caused by the spark plug being 'shy' of approx 3 to 4 threads when tight - the open threads are then exposed to the flame front and eventually crack.
Provided the cracks dont go under the valve seat,then they are generally ok to reuse.
If you have a good set of heads without cracks, then its wise to have the spark plug seats on the heads machined so the spark plugs have full engagement in the threads.
Mick
Provided the cracks dont go under the valve seat,then they are generally ok to reuse.
If you have a good set of heads without cracks, then its wise to have the spark plug seats on the heads machined so the spark plugs have full engagement in the threads.
Mick
#11
Scooby Regular
iTrader: (1)
No, not machined on the combustion chamber side - it's done on the opposite side where the spark plug tightens onto the head.
Material is machined off that face to allow the spark plug thread to come through flush and engage/use the open threads on the combustion chamber side.
Standard practice on the GRP N engines.
Hope this helps.
Mick
Material is machined off that face to allow the spark plug thread to come through flush and engage/use the open threads on the combustion chamber side.
Standard practice on the GRP N engines.
Hope this helps.
Mick
Last edited by merlin24; 13 August 2014 at 08:50 PM.
Thread
Thread Starter
Forum
Replies
Last Post
Mattybr5@MB Developments
Full Cars Breaking For Spares
12
18 November 2015 07:03 AM