Years ago I permanently fixed an exhaust leak on my GM equipped LH8 5.3 V8 Alpha H3 Hummer and I think everyone with an LS engine should know about the ARP Chromoly Header Bolt Kit. However, those ARP bolts alone won’t completely fix the annoying sound of an exhaust leak. If the problem is anything similar, a brand new header is going to be needed to completely eliminate the unhealthy engine noise.
When I first discovered the exhaust leak the issue could be temporarily fixed by tightening the bolts that hold the headers on. However, every month I would be back under the hood tightening down the same bolts because those bolts would have loosened back up. I repeated that process for months until one of the factory header bolts sheared off after using a bit too much elbow grease.
Having broken the bolt, I figured it would be clever to replace the bolt with a much stronger one. Searching the internet I found that the ARP part number 134-1102 Chromoly Header Bolt Kits works perfectly with the V8 in the H3 Hummer. The quality of the bolts from ARP are noticeably better. Just picking up the package of 12 bolts, it becomes apparent that they are heavy and dense. At 0.6 pounds for 12 bolts, it is very noticeable.
Now the only way to extract what was left of the old bolt was to completely remove the header. Considering that the bolts kept backing out and requiring tightening meant that the header was likely warped. Spending all this time to remove an old header just to extract a broken bolt doesn’t take any more effort to install a brand new header. A new header that is perfectly true and not warped will help eliminate the exhaust leak. Especially when considering that RockAuto has both GM Genuine factory headers at a great price. Currently, both sides are just $160 + shipping for both the passenger and driver side header. The part numbers are 12600527 and 12598548. Also, don’t forget to grab a couple of new header gaskets too instead of reusing the old ones.
I did heavily consider purchasing a set of shorty headers instead of the OEM headers but I decided against it. Worrying that there would be issues with clearance and fitment became the main reason I decided against a set of shorty equal-length headers. Also, worrying that by design a pair of shorty equal-length headers are probably gonna sacrifice low-end torque in favor of more horsepower higher up helped in making the final decision. Unless someones bombing through a desert at incredibly high speeds, more low-end torque is much more important than just a bit of extra horsepower high in RPMs.
I’m happy to say that I’ve had that new header installed on my passenger side for years now without any issues. I still think the quality of the ARP bolts is amazing. I’m so glad the engine sounds great and I don’t have to hear an annoying exhaust leak noise anymore. This old H3 has over 200,000+ miles on her. But she sounds great. And drives even better than anyone would expect. Especially since installing a Summit Racing SUM-8718R1 racing camshaft.