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 Post subject: cracked head
PostPosted: Sun Apr 29, 2007 6:44 pm 
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Joined: Fri May 19, 2006 9:54 am
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Location: cowra nsw
g'day im only 17 and my dad wants me to put in a post onhow you know if you have a cracked head on ya mini apart from bubbles in ya radiator andoverheating.
thanks


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PostPosted: Sun Apr 29, 2007 7:32 pm 
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Joined: Fri Jan 14, 2005 9:08 pm
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Location: Bris Vegas Occupation: Engineer
When you take it off you can get it tested at a head reconditioner. Most cracks you can't see.

It might just be a blown head gasket.

Regards

Daniel

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PostPosted: Sun Apr 29, 2007 7:53 pm 
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Joined: Tue Oct 17, 2006 6:20 pm
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Check and see if the valves and guides are very clean, because if they are, chances are the head is cracked, and also check for any signs of hoses that have blown, or are about to.
The hoses blow, because if there is a crack in the head, the vacuum of the pistons suck in coolant with fuel, and then push pressure back out of the crack, thus making the hoses pop.


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 Post subject:
PostPosted: Sun Apr 29, 2007 8:16 pm 
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Joined: Wed Feb 07, 2007 6:46 pm
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Location: sydney
another way u can tell is take it to a mechanic and tell them u want a tk test done on ur car to see if u have a cracked head, the problem with a cracked head is 2 things it will either crack chamber to jacket or from jacket to side of head. u can tell if its chamber to jacket by the tk test or bubbles in the radiator if that doesnt work, check the sides of the heads for bubbles appearing or water coming out

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 Post subject:
PostPosted: Sun Apr 29, 2007 8:42 pm 
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Joined: Fri Mar 19, 2004 6:19 pm
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Location: near Baulkham Hills, NSW
Apart from the original Mk1 Cooper S heads, Minis are not renowned as head crackers.
I've only ever had one cracked, that was a Minimatic with a flaw in the casting between chambers 1 and 2.
No worries- I just preheated it, bronze welded it, cooled it slow overnight, decked it flat, put it back on.. 8)
I've seen more cracked Mini blocks than cracked heads... :lol:

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 Post subject:
PostPosted: Sun Apr 29, 2007 8:43 pm 
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Joined: Fri May 19, 2006 9:54 am
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Location: cowra nsw
ok thanks for the info guys


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 Post subject:
PostPosted: Mon Apr 30, 2007 5:09 pm 
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Joined: Wed Apr 04, 2007 8:10 pm
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Location: Feilding, New Zealand
Yep like doc said very uncommon for a mini head to crack.But very likley a blowen head gasket.Take it to a garage and get a cylinder leakage test or a tk test.If head gasket is blowen why.Check all the basics like faulty thermostat/radiator cap/blocked radiator/faulty water pump dont just replace head gasket and hope it will be ok.The head could also warped and will need to be refaced

Cheers
Mason


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 Post subject:
PostPosted: Tue May 01, 2007 6:05 am 
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Joined: Fri Aug 26, 2005 1:03 pm
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Location: Napier, NZ
Just a slight hijack....is a crack in the end rocker pedestal mounting point (from bolt hole out to edge) a show stopper? Or would it really dpend on the crack?


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 Post subject:
PostPosted: Tue May 01, 2007 7:43 pm 
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smac wrote:
Just a slight hijack....is a crack in the end rocker pedestal mounting point (from bolt hole out to edge) a show stopper? Or would it really dpend on the crack?

No it's not- you can usually tap the hole a little deeper, or braze the pad corner and retap the hole.
What causes this breakage is people undoing the 4 rear head nuts before the 4 small ones on the rockers.. the valve spring tension then tips the rocker posts and studs forward.
Always undo the little nuts first, and do em up last. :wink:

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 Post subject: Wax
PostPosted: Tue May 01, 2007 11:16 pm 
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Location: Sthrn HiLoLands, NSW, Australia
drmini in aust wrote:
Apart from the original Mk1 Cooper S heads, Minis are not renowned as head crackers.


Except in the old days when people used Wax Thermostats that used to fail shut :oops:

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