blew my exhaust manifold off?????

B

BSMITH8315

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Aug 22, 2016
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Michigan
So I completely rebuilt a 1999 SRX this fall. Went completely through the whole sled all new hard ward gaskets bushing everywhere. Took it out this past Sunday for the first rip of the year. Clicked 162 flawless miles. Then it blew the chain case side exhaust manifold clear off and the bottom 2 bolts on the center manifold. They were all brand new YAMAHA bolts and I red lock tighten them. What would cause this???? as Im getting ready to put back together today.
 

Did the bolts simply back off or did it literally blow off breaking the studs? Read locktite won't work. Too much heat and it just melts it. I've never used locktite before just torque. Maybe the locktite melted and acted as a lube and they backed off?
 
3 sheered off and 3 backed out....putting it back together this afternoon and Ill try without the locktight
 
I would not have used any type of locktite either, from my FIRST rebuild to my last I have always torqued, rode around for 15 min the retorqued, Never had a problem. Well I did one time where I tightened all bolts went for my ride but missed re-tightening 2 bolts, which happened to be 2 exhaust manifold bolts which loosened right off. I only noticed later on because there was a black streak coming from the bottom of the manifold, lucky they didnt rattle out. As for the reason, Im not exactly sure other than the metal expanding, it being aluminum so it expands faster, because of the amount of heat produced and the vibrations from the engine itself.
 
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Make sure the 2 springs that hook from the bellypan to the pipes are hooked up they keep the pipes from rotating when hitting bumps. If you can move anything when all together you have issues with the mount above the shock or weak springs/bent spring flanges or worn donuts.
 
I'm thinking it was the loctite, unless you were using a special high temp kind. That's how I usually gets red loctite undone, heat it. When the loctite warmed up in your manifold, it turned liquid and acted as a lubricant instead of a locker. When the 3 backed out, the stress on the remaining 3 was too much. Though I'm with bluewho and check your pipe springs, doesn't seem like it should have broken 3 studs even with 3 that rattled loose. Then again these motors do vibrate quite a bit, maybe it broke off due to metal fatique...
 
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