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2007 Silverado 1500 LT 5.3 Z71 LH6 AFM Exhaust Leak

1K views 2 replies 2 participants last post by  rowdy76 
#1 ·
I have a 2007 Silverado 5.3 LT Z71 with the LH6 AFM aluminum block engine. At 156,xxx I had the engine rebuilt due to the oil consumption issue (1qt every 1000-1100 miles). Had an aftermarket warranty that paid for the rebuild after doing the consumption test recommended by GM. While doing the consumption test GM replaced the Left Valve Cover and put the shield in the oil pan. After the rebuild the oil burning issue is gone with a little over 30K miles driven.

Now I have a few issues that are minor in comparison but still issues. For this I am trying to tackle a exhaust manifold bolt issue. The shop that rebuilt the engine did a number that was covered up until recently. On the driver side rear the bolt must have snapped or broke off which is normal. The drill job they did now is not normal. They put a helicoil in but they obviously did not use a right angle drill. The hole was not deep enough and not straight. They also widened the opening killing any chance of a good seal. I found this while installing a set of headers. I had a slight leak but it didnt stay that way.

I ordered an oversized threadsert from McMaster Carr and did my best to correct the mess they made when I drilled it out. The insert went in fine after rethreading. I used an OEM metal gasket and torqued it down with new oem bolts. But still have a leak.

I am almost at a point to of the head off to fill in the hole and retap, but that is the last thing I want to do at this point. Any ideas about how to fill in the edges around the threadsert to get a good seal?
 
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#2 ·
Check this site to see if they have something that will work. I have used their product to fix the spark plug threads in a 5.4 Ford and they work great. They are expensive, but still cheaper than yanking the head off. http://www.timesert.com/ If they don't have something that will work you can remove the inner fender and a good welder should be able to fix it with the head on the truck.
 
#3 ·
Thanks, yeah that is similar to what I used. It was called a Threadsert made by mcmaster carr. It was oversized to allow for additional drilling but still kept the same ID for the factory bolt. The issue is when the idiot who drilled out the original hole for the helicoil he wallowed out the entry point. Threadsert fit in just fine with the whole I drilled per the specs given but it left a small gap once the insert was screwed in.

So I am wondering if there is anything I put around the port hole or around the opening for the bolt to seal that can withstand the heat.
 
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