| Re: Exhaust Manifold Rupture [message #304489 is a reply to message #304434] |
Fri, 29 July 2016 07:01   |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma:
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Clark,
I have seen such failures. What I can also tell you is that it is nothing remarkable, it was just a cast material failure that was run for a period at high load. The metal near the leak was both over heated and some carried away by the exhaust stream. It was most likely caused be an inclusion in the casting.
The use of hardened fasteners in exhaust systems in not advised. If you do, they should only be tensioned to level of a grade two fastener. All high grade parts get the increased strength from heat treatment. While this does require better alloys, after a short period at exhaust temperatures, the effects of heat treatment are just about gone. I also advise that if you did not coat the fasteners liberally with a good anti-sieze that you remove them and do so now. One of the side effects of the heat treatment and alloy is a propensity for galling.
Matt
Clark76 wrote on Thu, 28 July 2016 13:29I have already replaced it with another manifold from a local parts-coach. Also used new copper gasket, gasket seal, and new #8 hardened bolts and lock-washers. Took it on a long trip and no further issues. Clearly, the metal fatigued in the old Exhaust Manifold. I am just curious if anyone has seen a rupture like this before and if so, If they knew the cause, so it won't happen again.
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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