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Location:
Canberra
Registered:
May 2002
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 Re-torqueing head bolts - Hot or Cold??
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Mon, 20 May 2002 08:56
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When re-torqueing head bolts, should the motor be cold, or at operating temperature? what are the pros & cons of each?
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Location:
Newcastle
Registered:
May 2002
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 Re: Re-torqueing head bolts - Hot or Cold??
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Mon, 20 May 2002 10:47
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I beleive they should be done cold, due to the expansions of themetals and so forth, i am not too sure on the particulars but i have experienced it before if you put a bolt into something warm or hot when it cools down it basicly gets locked there forever.
technicly you should replace your head bolts each time they are undone but i know no one ever does it including me. it is to do with the stretching of the bolt when it is torqued down.
what you should do is take the bolt right out when you go to retorque them put a thin smear of oil on the thread, inder the head of the bolt and under the washer of the bolt if it has one, this is to reduce friction and give a true torque reading.
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I supported Toymods
Location:
Perth WA
Registered:
May 2002
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Re: Re-torqueing head bolts - Hot or Cold??
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Mon, 20 May 2002 10:55
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I don't have any direct experience, but thinking about it they must be done at the factory cold, and the specifications given must be for this. (?)
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Location:
Canberra
Registered:
May 2002
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Re: Re-torqueing head bolts - Hot or Cold??
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Mon, 20 May 2002 12:25
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thanks guys, that makes sense to do it when cold.
Celica RA40:
Are you sure its necessary to remove the bolts altogether? they've only been in the motor for a few hundred kays since assembly, and they were oiled well then, on the threads, and under the bolt heads. Even when i pulled the bolts out to remove the head last time after 10,000 or so kays, there was still plenty of oil on the bolts. 
Phil
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Location:
Newcastle
Registered:
May 2002
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Re: Re-torqueing head bolts - Hot or Cold??
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Tue, 21 May 2002 00:15
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Me again, this is what I was told when I got my motor back before I even contemplated starting/driving it,
1 - remove spark plugs and let engine turnover until oil pressure has built up.
2 - replace plugs and start engine, let it warm up to operating temperature then shut down.
3 - let engine cool again (left mine overnight) then re-torque the head bolts to appropriate settings, 60ft-lbs for standard head gasket according to Sean Moloney. (mine 75ft-lbs due to copper head gasket and o-ringed block/head)
4 - have fun 
This is what I was told and what I have done, it is only a guide, I'm sure opinions and practices vary.
Neil
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