Big_kid Posted December 2, 2021 Share Posted December 2, 2021 I have a couple broken exhaust manifold bolts. One on each side. The bolt head is 13mm on all of them. I see at the salvage yard about 95% are 10mm bolt heads. Do you think mine have been changed at some point or is it what ever GM used at the time. Thanks… Quote Link to comment Share on other sites More sharing options...
shakenfake Posted December 2, 2021 Share Posted December 2, 2021 Could have been changed. I suggest you purchase ARP bolts when you go to replace them. Quote Link to comment Share on other sites More sharing options...
2018GMC Posted December 2, 2021 Share Posted December 2, 2021 Here is a how to video. He mentions that the replacement bolts are different size than stock. Quote Link to comment Share on other sites More sharing options...
shakenfake Posted December 2, 2021 Share Posted December 2, 2021 I need to buy an acetylene torch... Quote Link to comment Share on other sites More sharing options...
richard wysong Posted December 2, 2021 Share Posted December 2, 2021 at least its not a Ford Quote Link to comment Share on other sites More sharing options...
Supreme Pizza Posted December 13, 2021 Share Posted December 13, 2021 I had to pull the head on my 5.3 recently, and I found that the very 1st and very last exhaust manifold bolts were both broken by a previous owner. To my surprise, all the other bolts came out with no problems at all. I drilled out the center of the broken bolts, and they came right out using a square easy out. I followed the OEM directions on re-installation, and everything has been good to go. As far as the size goes, I would just use what ever you have on hand, or buy some on Amazon. If you are torquing them correctly, I don't see why the bolt head size would matter at all. The instructions call for threadlocker/locktite and a specific torque spec, possibly with a 1st and 2nd pass if memory serves. Quote Link to comment Share on other sites More sharing options...
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