Remove exhaust manifold bolts hot or cold?

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JeremyNH

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I have some Gibson shorties I want to install on a 1998 5.7L Vortec. Gibson instructions say very specifically to remove the manifold bolts only with the engine cold using penetrating oil. 1A Auto has a good video where the mechanic says to make sure to run to operating temp before you loosen else you risk breaking the bolts. Which is the best way? I could see Gibson wanting to limit liability by warning not to work on a hot manifold. But then I have Aero-Kroil which has previously worked wonders on seized bolts in the past and may work just as well here. I just don't want to deal with broken bolts so thought I would post the question to those who have done it before.
 

man-a-fre

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I would spray your Kano Aero kroil on them( best penetrant made IMHO) when they are warmed up and remove them cold to keep from warping them and having to use manifold spreaders to install them next time. I realize you won't be using them again but this is the way I have had success doing it.
 
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