As diesel lovers, it doesn’t get much better than a Duramax – but it seems like they all suffer from one common problem: head gasket failures. We get a lot of questions about this topic, so here we’ll talk about some of the most frequent ones, give some insight on the repair process, and outline some issues that may need attention while those repairs are going on.
Why do Duramax head gaskets fail?
Let’s start with the biggest question: why do head gaskets fail?
Well, throughout the years, GM has revised their head gasket design multiple times and they each fail in their own unique way. No matter which gasket design your Duramax has, they are all susceptible to overheating – the #1 reason for failure.
Gaskets live a very hard life, in a harsh environment that deals with extreme temperature and pressure changes. These extremes mean that, in general, they are the first major engine component to fail – not only on a Duramax, but on most diesel vehicles.
When do head gaskets usually fail?
There is no real clear-cut answer for this question, which is often asked by new diesel owners. All we can really say is that it is typically the first major component to fail. However, there are some trends, based on the year the vehicle was manufactured.
How do I know if my head gaskets are blown?
The most common concern with blown head gaskets is the loss of engine coolant with no apparent visual leak.
When the gasket fails, the general problem is that cylinder pressure leaks into the cooling passage, over-pressurizing the cooling system and in turn pushing coolant out of the reservoir when it comes under heavy load. These trucks will start and idle without any smoke, and there can be no visual coolant loss, but the driver will have to constantly put more coolant into the system.
Many people think that they need to put in more coolant only when they are towing – because they are working the engine harder, putting more pressure into the cooling system, and the leaks occur while the truck is driving (and they don’t see the leak).
The 2006-2010 riveted gaskets are the only ones that don’t follow this pattern, because they do leak externally when they fail and rarely cause this over-pressurization. However, these will often have coolant puddles on the ground when the truck is parked overnight, making it easy to see that there is an issue.
Another good indicator of failed head gaskets is a “stiff” upper rad hose. If there are no external leaks, the cooling system can hold excessive pressure for months after the engine has been shut off. A simple test is to put the engine under a good load at operating temperature, then shut it down and let the engine cool off for 8 hours or more. If the upper rad hose is still firm and opening the coolant reservoir cap releases air and pressure, the head gaskets have almost certainly failed.
The last common indicator is constant coolant leaks. With the added pressure of failed gaskets, people may find they are constantly chasing coolant leaks – a never-ending battle of replacing water pumps or coolant lines and tightening clamps. When trucks roll into our shop for a basic water pump job, it’s common to find a failed head gasket on the truck.
Is Grade C the best head gasket?
This is a common misconception about the grades of head gaskets. GM has 4 different grades, A, B, C, and D, which are used to signify the dimensions of the gasket – and Grade C is the thickest factory-installed gasket. This means you can get a Grade C gasket in the 2001-2005 crimped style, the 2006-2010 riveted style, and the 2011-2016 gold colour.
The grading has no bearing on whether the gasket is good or bad, only on its thickness. In our opinion, the best gasket is the 2006-2010 riveted design, and it’s the only one we use on all of our head gasket repairs and engine builds, from stock to high horsepower competition engines.
Does my Duramax need head studs or bolts?
This question comes up all the time, and the truth is this: it is rarely the head bolts that cause the failure of the Duramax head gasket.
A Duramax is not a 6.0 Powerstroke, and the factory GM bolts are more than adequate. When we perform these head gasket jobs at the shop, we will warranty head bolts to 700WHP, far surpassing the “safe limit” of the factory pistons and connecting rods in a Duramax diesel. With head studs costing $900+ CDN and head bolts coming in under $200, we believe most customers that use their trucks for work , towing, or casual racing with mild to modest performance upgrades, could better spend that money on other upgrades.
Should I do any upgrades while replacing the head gaskets on my Duramax?
When we are performing a head gasket replacement, we must take apart the entire top end of the engine. This makes it a very good time to think about other performance upgrades, because there are little to no additional labour costs to do a lot of engine modifications.
For example, it can take 8-16 hours to remove the exhaust manifolds, up pipes, turbos, fuel injectors, and injections pumps. While we are there, we like to do any requested upgrades in that area of the engine. Depending on your end goals with the truck’s performance (and your overall budget), replacing gaskets and installing modifications are perfect to do together.
What is the cost to repair head gaskets?
A hard question, but it’s necessary to know! With the amount of teardown and rebuilding required in order to do the job correctly, it will take 36-44 hours to complete – there’s no other shortcuts to take. We recommend putting rebuilt heads on all trucks with mileage above 250,000 km because of worn valve guides. All in, the average cost is around $7,500 - $8,500.
Can I replace my head gaskets myself?
If you have the skills, sure – it is a large and complicated task, but it does come down to just nuts and bolts. Our recommendation is that you stay well-organized, have a spacious and clean work area, and clear out your schedule, because you’ll need a lot of spare time.
We have entire gasket packages on our shelf to get you everything you need to do the job correctly. Even pros like us started in our home garages, and we know the thrill of getting things done DIY-style, so feel free to tackle the project – and if you need any help to finish it off, you know where to find us!