dasher1 Posted July 23, 2011 Share Posted July 23, 2011 Hi everyone, I need some advice & help - due to a series of "ham fisted" events (long story), I've managed to crack & break the left front valve cover bolt boss on the cylinder head. So my question is … What's the best way to fix this with out buying a new cylinder head? Can i use JB Weld and drill & tap it? Also, whats the best way to set a new rubber bushing into the valve cover bolt into the valve cover? Thanks for any and all help, i've posted this across several boards Link to comment
Danny caddyshack Noonan Posted July 24, 2011 Share Posted July 24, 2011 The rubber bushing and screw come right out of the cover with a little convincing. The new one will go in with a bit of motor oil. Broken boss? Epoxy, weld or new head. It's going to depend on how much parent material is or isn't there. Epoxies are fairly tenacious bonding agents with aluminum. However, at temperature they soften and the tensile properties fall off rapidly but, that's at around 300F minimum. I suspect intake temperatures don't exceed that on the boss but don't know about the exhaust side. Go look at the failure location and see if there is enough thread hole remaining on the head that a long helicoil or keensert might help retain the bond. If so, consider that as an option for rebonding the boss...epoxy and mechanical retention. My first try would be with either JB or to order a high temperature 4000 psi tensile minimum epoxy. Clean everything with Acetone and soak the loose part in it. Let dry a minimum of 15 minutes. Then glue it back on, wait 2X the cure time for maximum strength and then either install a thread repair or test the existing thread for strength. Getting a new head is a much shorter reply. Link to comment
dasher1 Posted July 24, 2011 Author Share Posted July 24, 2011 I've gone with the JB Weld, it built up nicely, will try drilling & tapping it tomorrow 74c5 thanks for your reply & info Link to comment
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