Duramax Head Gasket Replacement

[Robyn]

Also.....doing the job yourself ensures that it gets done right in many cases.....YOU are going to take a second look at anything that seems a tad hinky.....as compared to the shop mechanic that MAY NOT give it a second thought....

[More Power]

You're right Robyn.

Mechanics and shop owners have a somewhat different motivation than do owners. They are worried about come-backs and liability, as well as producing a satisfied customer (or they should be). Shops also rely on their mechanic staff to do all that, while trying to keep the best mechanics and make the shop profitable (the really talented mechanics usually go out on their own). Shops have a lot of competing interests, which is partly why they do the "As Long As We're in There" routine with up-selling every job that comes in. There are a lot of good mechanics out there and there are a lot that aren't. I've heard so many horror stories through the years from GM diesel owners.

Jim

[Robyn]

I agree on the "Upselling" many times these things are done to "Cover the dealer/shops butt"

A side story.

My tenant that lives in the lower level of our place has a 2002 Jeep Cherokee with a V8
It has been giving issues off and on for a few weeks now.
I DO NOT WANT TO BE HER "GO TO MECHANIC" although on occasion I have wrenched on her rig to get it going so she can make it to work....(Important if I expect rent payment)

The Jeep started stalling.....I grabbed the scan tool and checked it out..../A failing crank sensor..

She took it to a shop close to her work....They installed the new sensor.....On the way home it died about 4 blocks from the shop....

Shop sends the mobile unit out and he determines that the tranny is burnt up and needs replacing.. Hmmmmmmmmmmmmmmmmmmm

She calls me and I told her....DO NOT DO ANYTHING.....NURSE IT HOME.

I check the tranny fluid....PINK AND SMELLS PURRRRRRRRRRRRRRRRRFECT.

Tranny shifts fine.
Every so often at light throttle the engine would just die....

Throttle position sensor and the idle air control are suspect in my book..

The TPS was replaced about 3 years ago due to a similar issue (Engine speed surging up and down)

I suspect the NAPA part that was installed (Made in China) is giving up....

Idle air control dirty with carbon and crud can and does cause stalling......

Sharis called another shop....told them the story....

Fella puts his scan tool on the JEEP and tells her she needs a new ECM

Nobody has hit on the IAC and TPS
She has been quoted MEGA $$$$$$$$$$$$$$$$$$$$$$$$$$$ to chase this anomaly....of which none of the FIXES will do anything accept take her money..

What I have seen so far is mechanics that rely waaaaaaay too much on the magic box scan tools.

If the tool does not tell them what's wrong....they default to a WILD ASS GUESS.....

They need to learn "Butt dyno" and basic automotive skills.

If the scanner is not showing anything then its not electronic (Generally)

Back in the day.....when a screw driver and a crescent wrench were king....We had to THINK


I digress


Glad to hear that the Daughter is interested in learning the art of swinging a wrench...
Definitely be good for her to have a good handle on all things automotive.....Then she will be able to know when she is being told BS....

[More Power]

I suspect the NAPA part that was installed (Made in China) is giving up....

Not much available in any auto parts store that's not made in china... They've all turned into Harbor Freight. (although HF is starting to grow on me... I bought a number of wrenches from them recently, including a 3' long 3/4" breaker bar - now that's a manly wrench!)

[Robyn]

Yes indeed
Big Ma break stuff type wrench

I avoid screw drivers and such. Pretty much junk
I have a set of impact sockets I bought back in the 80’s when HF was mail order only

Still 100% shape and been beat unmercifully over the decades

I have several power tools from HF
No complaints
Just need to treat them with a bit of care as opposed to tossing in the truck with a heavy hand

I have a 12” double miter saw, a hand held band saw snd a few other tools

All are great tools

Several air tools including my air compressor came from HF
My old air compressor died after 30 plus years of serious abuse

Ran to HF and picked up the Squatty top compressor unit on wheels

Works great
The Cat project has already put 16 hours on the beast

I have one of their multi meters snd it’s been great too

Most stuff from HF is great for hobby shop or moderate use and will live a long time if taken any dirt of care of

Oil the air tools and be somewhat careful of plastic handles and such

I have an ancient horizontal metal band saw that still fills in when we need two machines

My Son in law picked up a nice Jet band saw that has the protractor head on it

He found it sitting in a driveway near his house with a sign FOR Sale
This model is about $1000 and we got it for $500
Just requires a very easy feed or the band will pop off
That was common in that model

But for the price ..: good tool

HF is my Toy store

I will not buy their 18 bolt stuff

The 1plus from Home Depot have been great
Have Ridgid brand too
Both great tools

I like having several tools that use one battery and charger
The lithium ion batteries are sooooooo much better than the old chemistry stuff

Got one of those battery chain saws
Great for that little job that you don’t want to go get the gas saw and fool with it....

Tools ... great toys for busy hands

[arveetek]

Harbor Freight quality has really increased a bunch lately, it appears to me. However, so have the prices. Case in point - their "pro" 1/2" drive torque wrench is $109. I picked up a Craftsmen brand from Lowes for $89.

Casey

[Robyn]

Looking great.

I have seen this view before a few times...... always a good feeling when ya get the crank in and start stuffing the little soldiers back in their holes.....

The sorting through the parts boxes is always fun....especially when others have torn stuff apart.

When the Dahooley came down the last time I knew it was going to be a lengthly period of time until it went back together.

Stopped at the grocery store and grabbed a few boxes of the various sizes of plastic zip lock bags.

Bagged and tagged all the bolts. nuts and sundry other small items.

Made the reassemble a breeze....No matter what was happening, a quick sort through the bags of goodies and whatever was needed was in hand and ready to go.

When the hood was closed for the final time ....all the bags were empty and nothing missing or left over.

Really makes me wonder why some folks toss all the bolts and such in a bucket and then have to sort through it all later....


Too much like work and frustration me thinks......

[More Power]

Bagged and tagged all the bolts. nuts and sundry other small items.

Yup... We used about 20 such cups for hardware during the Duramax head gaskets jobs, and I kept as much of the hardware as was practical with the items being removed. All of this speeds the reassembly process considerably. Unfortunately, the 6.5 was disassembled by someone who didn't know - who hadn't done this before, as evidenced by the fact that they ruined the original crankshaft getting it out of the block (gouged journals) and not protecting vulnerable inner parts from moisture (i.e. most of the lifters were ruined by rust and none of it was kept clean). There are about a dozen cups with hardware, but most weren't labeled (or the lettering rubbed off) and there appears to be a mixture of fasteners in some cups. Reminds me of the time that, as a teen in the '60s, I bought a basket case 1938 Harley Knucklehead for $75 that I turned into a bobber. Fun times! My spine winces a bit when I think of riding that bike.

[Robyn]

Sad to see stuff trashed.....but it happens.

[arveetek]

I watched an ARP video a while back where they discussed the "elastic" clamping load supplied by properly installed and torqued Series-2000 head studs produced for the Duramax. I like it that the ~$650 head studs have some elasticity designed-in.

However, we know that GM is still using TTY bolts in the newest L5P Duramax, which is rated for 445 hp / 910 lb-ft - and rated for up to a 35,000-lb GCVWR.

I interviewed the "Duramax Power Tour" team in 2000, who drove an LB7 equipped 3500-series truck towing a 20,000-lb event trailer. I rode in that truck as they wailed on it, on the I-90 continental divide pass just east of Butte, Montana. I asked them if they drove it like that all the time. I was told yes... They put in excess of 20,000 miles on that truck - hammer down all the time. I can also point to a 750,000-mile LLY Duramax used to commercial tow RV trailers all over North America, that I wrote about a few years ago. GM could acquire head studs equal to those offered by ARP (maybe even contract with them to provide) if they felt it was necessary.

I have a couple of debate points about studs that are hard to answer and difficult to challenge. 1- The aftermarket pushes anything that they can sell - ("while you're in there") type of stuff, including head studs. 2- Studs are simply easier to install than TTY bolts. You must mark the heads of each TTY bolt during the two angle tightening sequences or you'll mess up the installation. With studs, you only use a torque wrench. If you forget one or get out of sequence, it's really easy to check what the torque is for that stud. Personally, I think this is why many vendors/mechanics push studs (sell more expensive stuff and they are easier to install). Otherwise, they would/could point to actual durability tests involving direct comparisons between engines using head studs and TTY bolts (fleets would be the best source of information. Second best would be an accumulation of real-world reports from actual owners - like the story I did on the 751k mile LLY Duramax). For most, these head gaskets will wear out long before any real comparison can be done on the veracity of claims otherwise.

I have the opportunity to purchase some new ARP head studs for my 6.5L for the same cost as new TTY head bolts. Is there any reason NOT to use head studs in my application? This is a stock 6.5L with 375K on the clock and no other issues other than a blown head gasket. John Kennedy recommends studs.

Thanks,

Casey

[More Power]

I have the opportunity to purchase some new ARP head studs for my 6.5L for the same cost as new TTY head bolts. Is there any reason NOT to use head studs in my application? This is a stock 6.5L with 375K on the clock and no other issues other than a blown head gasket. John Kennedy recommends studs.

Thanks,

Casey

I can easily make the case for TTY - which includes the quote you included in your post. What was not in that quote was the head gasket durability I saw with our 6.5TD Power Project, using TTY bolts (300K miles of mostly towing/performance miles without a single head gasket problem).

It's disappointing that "some" get perturbed when asked to provide support for their position. I don't understand it. If studs are better, state why you believe that... I have nothing to gain otherwise by promoting one type of fastener over another (I actually lost a vendor over this very issue). As an information resource (thedieselpage.com) I have more to gain by promoting the "best" option. There are several criteria for what could be considered "best". "Best" could defined as proven better - sorta like how the FDA approves new drugs (blind studies - direct comparisons). "Best" could be defined as being more than adequate for the vast majority of the owners while saving them a lot of money in the cost of fasteners. What's not "best" is theoretical or an arm chair opinion. I would ask the stud advocates to put some verifiable high mileage examples of head stud usage on the table to consider - like the following high mileage TTY head bolt example I talked about a couple of years ago - 772,470 miles, which backs up the story I did on the 751k C2500 Duramax RV hauler and our own 300k-mile 6.5TD Power project... Read more about high mileage Duramax trucks here: https://www.thedieselpageforums.com/...-March-updates



It used to be back in the early days of the 6.2/6.5 that GM's head gasket suppliers hadn't figured out how to design a gasket that worked for these engines. Far too many head gaskets failed in these engines because of poor gasket design, and that's when the aftermarket (and others) began advocating for studs for the 6.2L/6.5L. Then one day Fel-Pro designed the best head gasket, and head gasket failures almost disappeared. Turns out that the problem was never the fastener but the gasket design. But, old opinions die hard. By the way... throughout the early years of the 6.2L diesel engine production, GM used head bolts that were not TTY. They were simply torqued to a specified torque value in steps... like stud nuts are now. GM could have stayed with non-yielding head bolts, but they switched to TTY early and continued through to the end of their own production of this engine, and AMG continued to use TTY when they took over 6.5 production.

So, to answer your question.... because of their elastic head clamping design that compensates for thermal cycles and gasket compression (and my own verifiable long-term experience/success with them), I prefer TTY, especially for the 6.5. Now, for the Duramax, if cost is taken out of the equation, it's more of a toss-up in choice except perhaps for a high power (2x+) application, then ARP's engineering data "begins" to sway my opinion. But, even that is simply theoretical. ARP's own ad claims in the Northern Auto Parts catalog, when talking about diesel stud kits, say that their studs are preferred among "racing" enthusiasts. That said, I'm quite content in my choice of TTY for Lil Red's Duramax because it has been retired from any sort of racing/dyno/nitrous duty. The 6.5 I'm putting together right now will get Fel-Pro TTY head bolts along with Fel-Pro head gaskets... just like our 6.5TD Power Project did in 1999. Besides, due to the limitations in fuel delivery of the DS/DB fuel injection system, the 6.5 can't be made to produce a horsepower level that justifies studs... in my humble opinion.

Jim

[Robyn]

GM spent a buttload of $$$$$ designing things (Bean counters not included in the equation)

But even the best engineering will not always stand up to road testing by "Bubba"

I think you are pretty close to the mark....

The Monday morning quarter backers.....always...woulda, shoulda, coulda types always have an answer to every issue.. "My buddies uncles shop" does it this way......

Ah well.

Such is life....

[More Power]

GM spent a buttload of $$$$$ designing things (Bean counters not included in the equation)

...

I'd bet that "if" GM believed studs were best, they could contract with ARP or another manufacturer to provide head studs for the Duramax. DMAX has produced millions of these engines. That should allow for a pretty deep discount on quantity buying.

By the way, the engine shop I visited, to get my GMC's aluminum heads resurfaced, also builds Duramax engines for their retail market. They offer a 5 year warranty on their top of the line Duramax engines, and they only use ARP head studs and Mahle gaskets. The owner is a nice guy, and I didn't press him by asking "how he knows they're best?". I was there to make friends. Sometimes people forget or simply don't know how much experience I have with these engines - and how many people I've talked to in more than 2 decades. I always allow room for others to have their own opinion, even if it is based on theory or... If their position is fixed, I move on.

An additional item I found during the Duramax head gasket replacement project(s)... The Mahle head gaskets made for the Duramax don't seem to compress overnight after having the fasteners (either stud nuts or TTY bolts) torqued to their second-to-last torque setting (59 ft-lbs). When checked the next morning, the torque setting was still right where I left it. So, there's no need to pause overnight, then re-torque to 59 ft-lbs the next morning, before moving on to the last step in stud/TTY tightening.

Jim

[Robyn]

Allowing folks their latitude is usually a great plan to make inroads.....

The folks that really irritate me are those that say.....WHATEVER IT IS ....You can't do it that way...."Why" BECAUSE....IT WON'T WORK.....

No explanation....just because....

Arrrrrrrrgh....

[More Power]

I haven't talked much about the injectors I used for the two Duramax head gasket projects discussed in this topic thread, and after having lived with the choices I've made for some weeks now, I think I have enough information to talk about the differences between the original VCO type injectors (stock type used in the LB7) and the more recently available SAC type that I installed in my GMC during the head gasket replacement.

First, a little background: The original 2001-2004 LB7 high pressure common rail fuel injection system operates at up to 23,000-psi fuel rail pressure. The more recent model year Duramax operates with up to 29,000-psi rail pressure. We all know that high pressure liquids can erode even hardened components. For example, the Duramax conversion motor mounts we sell here at thedieselpage.com are made from 3/16" plate steel cut from large sheets using a computer controlled water jet system. It cleanly and smoothly cuts steel plate like butter. The Bosch fuel injectors use hardened components designed to deal with the high pressure diesel fuel... but, there is a design difference between injectors made to operate at up to 23,000-psi and those designed to work at up to 29,000-psi. The aftermarket (S&S Diesel) began offering the SAC type injectors for the LB7 in about 2018, which combine some of the 29,000-psi nozzle components in an injector body that fits the LB7. Longer nozzle life is the leading ad claim. That's the upside... but, is there a downside? Turns out... yes...

According to the web site: https://powerdrivendiesel.com/differ...sac-injectors/ , the acronym VCO is derived from (Valve Covering Orifice), where SAC style nozzles utilize a different shaped orifice that is said to provide more longevity. The site didn't say what the letters SAC mean..., but they do mention a difference in the level of combustion rattle (noise) produced by the engine depending on which type of injector is installed - confirming what I experienced. I didn't know this before the SAC installation...

In real terms, there are a few differences you will notice the first time you start your LB7 Duramax after installing the new SAC injectors.

Originally equipped with VCO, my 2001 GMC got the new stock flow rate SAC type injectors during re-assembly. After all this work, the engine appears to start almost instantly with a much crisper "ccrraacckk" sound. While motoring around town, you can hear more combustion rattle in general along with a background of light secondary rattle (like shaking an empty soup can with a dozen BBs inside). I don't see anything in the way of smoke, either during a cold start (it's summertime) or when accelerating hard - boost goes to 20-psi. Seems to be very clean for a 141,000 mile engine. At secondary road speeds (55-65-ish) the increase in combustion rattle produced by the SAC injectors can be a bit annoying... it's as though the pilot injection has been reduced or is only marginally effective. Haven't had it on the Interstate yet. By the way, my GMC is running with a 100% stock factory-programmed ECM and without any sort of power adder. There is no SES light.

For Lil Red, I re-installed the very same factory original VCO injectors that this particular LB7 came with - now with just over 8,000 miles on it. Not surprisingly, the engine sounds exactly like it did before the head gasket replacement. Its combustion rattle is relatively quiet, just like it was before. In terms of combustion rattle, it's noticeably quieter now than the GMC... By the way, I went to considerable lengths to keep Lil Red's injectors clean and uncontaminated during dis-assembly, storage and re-assembly. I must have done a good enough job because the engine runs just as smoothly now as it did before all of the engine work.

The original VCO injectors in my GMC crew cab ran to about 120,000 miles before #2 set a fuel-rate balance code (P0302). Not long after, a local diesel shop installed a full set of VCO reman injectors for me (I know, I know... I should have done it...). After about 4 years and ~20,000 miles (now 140,000 miles total on the truck), I was beginning to see a little blue fuel smoke at a cold start that quickly went away and didn't return till the next cold start. It ran well enough with those reman VCO injectors, and the combustion rattle was just like it was with the factory original set of injectors. I decided not to re-install this 20k-mile set of injectors during the head gasket replacement because of the blue puff at a cold start - "as long as you're in there", I thought. By the way, I've always used a commercial diesel fuel treatment in this truck (lubricity, cetane, anti-corrosion, cleaner, etc.). I had originally planned on taking the GMC's injectors to a local certified shop for testing and cleaning (if they would do it), then re-install them, but doing the work myself saved so much money that I splurged a bit on new reman injectors.

Going forward, the only reason I can see for choosing the SAC type injectors is longer life (theoretical - yet unproven), which would be a good reason... but, I know now that the VCO type injectors offer a much quieter operation - and that's important to me as well.

What would I choose if doing the GMC again? I'm thinking I'd choose VCO... And, I would investigate the service life data and cost differences comparing reman Bosch injectors with new Bosch injectors as part of the decision making process, as well as looking to solve some of these injector problems on my own work bench using the available replacement parts. All that said, I'm glad I reinstalled the original VCO injectors in Lil Red.

Jim

[Robyn]

Interesting stuff.....

[DieselDavy]

Hey Jim,
I'm wondering if John could spin some new code to quiet the GMC down. See what he says.....

[More Power]

As an aside... During the opening phase of these two head gasket replacement projects I became acutely aware of the enormous cost potential, especially if a truck owner took the advice of the "replace it as long as you're in there" crowd and replaced or upgraded everything. Doesn't take long to cross the line in economic sanity.

As my work progressed, I assumed I'd need a water pump for the GMC, even though it had been replaced just 3 years earlier. I thought this because I could smell hot coolant after a drive, parking, then walking around the front of the truck. I just assumed the water pump seal had surrendered to the excess pressure, so I bought a new water pump from Kennedy (like most things I needed) so it could be replaced as part of this head gasket replacement project.

During the tear-down I noticed that most fittings/joints/connections in the thermostat housing area had been oozing coolant for quite some time. The coolant ooze had run down the front of the engine behind the fan pulley assembly, producing the hot coolant smell. That made me curious, so I then carefully examined the weep hole on the bottom of the water pump, to see if it showed any evidence of coolant leakage. That weep hole is somewhat hard to see - it takes some effort to be sure about it. Turns out the weep hole was bone dry and was without any dried coolant residue. So, there were no water pump seal leaks. As a consequence, I didn't replace that 3 year old water pump. It wasn't leaking then and still isn't. I left the brand new water pump on the shelf, "standing by, just in case" for the Lil Red project.

When Lil Red was at the same place in its head gasket replacement, I examined its water pump weep hole. Nary a hint of leakage... So, I kept the new Kennedy AC Delco water pump (with welded impeller) on the shelf. I've driven Lil Red about 4,000 miles and the GMC about 8,000 miles since replacing the head gaskets (now ~13 months after the fact - September 23, 2022). Everything remains perfectly dry and without a whiff of a coolant leak... After having done these two head gasket replacements, I now know that a water pump replacement is, by comparison, cake (I've participated in one complete WP replacement)... Besides, I still have that new Harbor Freight 3 foot long 3/4" breaker bar I mentioned a few weeks ago, just in case I need to remove the damper during a water pump replacement.

[More Power]

Hey Jim,
I'm wondering if John could spin some new code to quiet the GMC down. See what he says.....

I wondered about that. I suspect he's reading this thread.

Experience... you'd think that at some point a person would have a good handle on what to ask - live long enough and you'd become that wise old sage. Seems I'm still learning...

S&S has an info page that talks about and discusses the benefits of SAC. I should have asked them about downsides... didn't see any on their web site. I thought maybe I'd screwed up during the install because the truck was so much noisier with combustion rattle... Then I started doing a little research online... I also wonder about potential impacts to power and fuel economy - by comparison to VCO. I've been tracking fuel economy in the GMC... I'll report what I find when I have enough information to form an opinion. Jim

On edit (9/15/2021): Fuel economy so far... has been in the range of 15-17 mpg for mostly local driving, so my guess is that the fuel economy hasn't been affected all that much - that's about what it did pre-head gaskets with the VCO injectors. I'll know more when we drive it on the interstate for a few hundreds. The GMC has nearly 2,000 miles on it since the head gasket replacement.

On edit (2/1/2023): The GMC is coming up on 10,000 miles since the head gasket and injector replacement. I've gotten more or less used to the increase in combustion rattle. The engine runs smoothly, and continues to perform very well without any sort of problem. It's wonderful knowing that I can jump in the truck, and can go anywhere without worrying about whether or not the cooling system will dump its contents out onto the highway. We love this truck. I'd rather drive it than our Chevy Malibu, anytime, anywhere - for the room, the comfort, and the safety...

[arveetek]

I thought maybe I'd screwed up during the install because the truck was so much noisier with combustion rattle...

Sounds like a good thing to me! That's actually one of the things I don't like about the newer diesels... they are too quiet. I love the older, clattering diesels.

Casey