August 14, 2023 - Head Gasket Replacement Update
It's now been a little over 2 years, and the truck has accumulated nearly 13,000 miles since my daughter and I replaced the head gaskets, injectors and injector fuel lines, and resealed the injector cups, resurfaced the head decks and set the valve lash in my 2001 GMC's Duramax 6600. The truck continues to run great, and there has not been a single issue with the head gaskets or any other aspect of the tear-down and re-assembly (other than a minor fuel and coolant leak after the initial startup the first day after the service - that were easily taken care of). None of the head gasket service videos that I've seen online talk about how successful their repairs were over time. A rather important point, considering the "dubious" repair procedures shown in the videos... So, other than to share a little of Montana with you, that's the reason for this update - to talk about the success of the head gasket replacement project that was completed in June of 2021 - done the right way. ;)
https://www.thedieselpageforums.com/...9&d=1692026290
Nearly a hundred miles from home, this pic was snapped on Thursday, August 10th looking north from an overlook situated above the southern end of the beautiful Flathead Lake here in western Montana. Just over the hill and to the left a couple of miles is the small town of Polson, Montana. However, our destination that day was to the right in this photo, on the eastern shore of the lake, to a public facility called Finley Point State Park. We had rented a cabin there for a few days. This trip was possible because the new head gaskets have made the truck a reliable member of the family again.
Flathead lake is among the largest freshwater lakes in the country, being 28 miles long, up to 15 miles wide, and 370 feet deep at its deepest point. The scenic value of this natural wonder is awe inspiring, especially when set against the glacially carved and rugged Mission Mountain Range just off camera to the right. This mountain range reminds me of the glacially carved topography found in Yosemite. Flathead Lake is the result of a very large glacier that had scooped out the lake bottom during the last ice age. This elevated overlook where the truck is sitting is a "terminal moraine" that had been bulldozed into place by that glacier, and which also defines the southern boundary of the Continental Ice Sheet that once covered all of Canada and a northern fraction of what would become the US's lower 48.
We were here, partly, to kayak and to try our hands at fishing. Flathead Lake contains Lake Trout up to 40", good sized Lake Whitefish, Kokanee salmon and several other species (bass, perch, etc). My experience with fishing the lake was pretty limited, but the Zimmerman bait/tackle shop in Ronan, MT set us up with a selection of the right gear, and showed us a chart with water depths describing where each species would be located. This time of year, the bigger fish are all in deeper water, so my daughter and I jigged for Whitefish using artificial lures in about 100-150 feet of water - offshore from Blue Bay. I caught one and had several others on the line. The Whitefish we battled were about 2+ lbs and about 24" in length. Though the limit was a hard-to-imagine 100 per day, we were just catch-release fishing. We found the Whitefish to be hard fighters when using light tackle, and when in a kayak!
We had beautiful weather this trip, and the many cherry orchards around the lake had produced a bountiful crop - there were many open fruit stands all along the roadways. The large Bing cherries were delicious! My daughter even fed a few cherries to a Whitetail doe and fawn just a few feet off the front porch of our rented cabin.
See my signature below for a link to a page that describes our printed and bound Duramax Diesel Service Guide book, which includes a number of service procedures for the Duramax 6600 - including a head gasket replacement project. Do it once, do it right. :)
Jim Bigley
PS - The name "Flathead" came about because of a native tribe that once inhabited this area. Their custom was to bind boards against the heads of younger members of their group, thus modifying their skull shape over time. This was similar to what was practiced by a few native tribes found in both North and South America.
Today, the southern half of Flathead Lake and continuing south for another 50 miles is all within the boundary of the beautiful Flathead Indian Reservation. There is much to see and do within the Reservation, and I encourage those visiting this area to take advantage of the opportunity. Fishing on the reservation requires a reservation permit - available at any license counter here in western Montana or online.
I've known and even worked with a few natives from this area - going back to when I was a teen, and up through the 1990's when I assisted their tribal college to complete the setup and repair of some science tech I was trained for at the University of Montana. We met and talked with a handful of natives during this August 2023 visit. They're still the real deal... This area is a bright spot among Indian reservations. It's beautiful here. You'll be blessed for having visited.
October 27, 2023 - Update on Head/Block Prep
I've mentioned here before that Youtube can be a fun place to hang out or learn something you didn't know. However, when it comes to working on your Duramax 6600, a little common sense can go a long way. Back in 2021, I did a search on YT about Duramax 6600 head gasket replacements... I found the most popular video in the list of those I watched to be one where the mechanic was using a horrible technique to prepare the block deck for new gaskets... Here's a screen grab. Yikes!
https://www.thedieselpageforums.com/...1&d=1698432471
The above image would be appropriate if he was grinding off a half inch of body filler - but this is not appropriate prep for new head gaskets. To compound the problem, there is absolutely no attempt to prevent carborundum grinding grit and debris from falling into the lifter galley, onto the piston crowns or into the cooling passages. This is NOT how GM specifies the heads and block decks are to be prepared...
The next image shows what IS recommended by GM - to help prepare the Duramax 6600 head and block deck surfaces.
https://www.thedieselpageforums.com/...2&d=1698433033
This is a 3"x4" steel block that was machined flat on a milling machine. GM recommends using a light oil (I used WD-40) with 600-grit wet/dry paper on the pictured steel block to prepare the cast iron block and aluminum head deck surfaces. I also stuffed the lifter galleys and piston crowns with clean shop rags, and any accumulating oily sludge was prevented from entering the cooling passages. Our Service Guide linked-to below shows how this is done.
The Duramax 6600 head gaskets require a certain smoothness for both the block and head deck surfaces. The design of the head gaskets require this smoothness, and the differing temperature coefficient of expansion between the aluminum heads and cast-iron block demands it. 600-grit provides that smoothness, when used with an absolutely flat steel block.
I had a local fabricator make this block for me, but you could create your own by using a 4" length of 3" steel angle iron. Then make it flat by using a series of coarse/fine grit wet/dry sand paper sheets on glass or a flat counter top. Round the edges before completing the job - so they can't dig into the aluminum heads.
The job of preparing the heads and block isn't that difficult and it goes pretty fast. Jim
Head Studs V. Factory Head Bolts
https://youtube.com/shorts/pySyCI1lR...HunvXKqYnAoKzp
I know that the debate regarding whether to choose head studs or head bolts for a Duramax 6600 will likely never be completely resolved, but here's another voice that addresses the question... ;)
I like Gale Banks. I've met him personally a couple of times, had dinner with him, and we've talked on the phone/email. But... Now, to be fair, the image he uses in this video of block deck bolt thread failure is NOT of a Duramax 6600. I don't know what engine is represented by that pic. You can see in the image in a previous post (of mine) what the block deck actually looks like in a Duramax 6600. The bolt holes are much different, and far less likely to fail like that shown in the Banks video.
Still... I believe Banks would be running studs and selling his own stud kits if he thought studs were either necessary or even just a better choice. Studs are a fairly expensive option. Gale is a businessman...