My knowledge of auto repair ends at recognizing a blown head gasket is a major problem. How does one prevent this from happening? I just had one blow on an old '97 Sable and I'm in the market for a new car. It seem like if you google (insert desired car here) and head gasket, you will find complaints about this issue. What kind of preventative maintenance can be done extend the life of head gaskets? Should the gaskets be replaced at a set amount of mileage?
Head Gaskets
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Don't run it out of coolant......They don't need to be replaced if they're not leaking.
A blown head gasket is bound to happen to just about any car. Some engines are prone to head gasket problems, most aren't. They mostly blow when the engine is overheated. There isn't really anything you can do to prevent a failure except make sure the cooling system is in good shape and don't overheat the engine. I would not replace them as preventative maintenance. The odds of having a failure (on an engine not prone to failures) where the cooling system is in good shape and not overheated is super slim, and the cost of replacing the head gasket is too much to do a "just in case" replacement.
Outside of overheating an engine (and certain GM v6's, Honda's from the mid 90's) it's fairly uncommon to hear of. But it could happen on any car so I'm sure the internet would yield results for anything. Keep your cooling system in decent shape and worry about something else.
The only real preventitive maintenance you can do is to maintain the cooling system (both so the car doesn't overheat, and also so the coolant doesn't wear out and turn corrosive).
Honestly, though, the main factor is engine design. Some engines are prone to headgasket failures, like the subaru 2.5, the ford 3.8, toyota inline-6s from the 80's, and some others. I'd be willing to bet the engine in your sable was the OHV vulcan, not the DOHC duratec, right? The vulcan is somewhat known for head gasket failures but I pretty much never hear about it happening to the duratec.
Honestly, though, the main factor is engine design. Some engines are prone to headgasket failures, like the subaru 2.5, the ford 3.8, toyota inline-6s from the 80's, and some others. I'd be willing to bet the engine in your sable was the OHV vulcan, not the DOHC duratec, right? The vulcan is somewhat known for head gasket failures but I pretty much never hear about it happening to the duratec.
Yes, I have 3.0 Vulcan. I'm really interested in a Subaru Outback, but again, head gasket issues. If I get the 6 cylinder Outback, do the head gasket problems go away? When you say maintain the cooling system, what all does that entail?
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The 6-cylinder subarus are fine. It's also suspected that the new subaru FB engine (used in the forester and non-wrx impreza, so far) will be much better as well because it has a smaller bore and longer stroke which makes the gasket thicker between the cylinders.
Maintaining the cooling system pretty much just means changing the coolant according to the manufacturer's schedule (typically 50-100k miles or 3-5 years. age matters!). I've never had to replace a radiator in any of my cars but it can sometimes be needed in rust-prone areas.
Maintaining the cooling system pretty much just means changing the coolant according to the manufacturer's schedule (typically 50-100k miles or 3-5 years. age matters!). I've never had to replace a radiator in any of my cars but it can sometimes be needed in rust-prone areas.
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Some amazing misinformation here. The link between engine design and head gasket failure is very tenuous.
In addition, bore and stroke means absolutely NOTHING to head gasket thickness.
In addition, bore and stroke means absolutely NOTHING to head gasket thickness.
Bore absolutely has something to do with head gaskets. I didn't mean the thickness vertically between the block and the head, I meant the amount of gasket material between cylinder bores. In the same block, a larger bore will have less space for the gasket to fill between the cylinders. This is why the subaru 2.5 is bad about blowing head gaskets but the 2.2L version is not. The 2.5 has a larger bore and this bore is too large for the block and the head gasket material. This is also why GM reduced the northstar v8 from 4.6 to 4.4 liters for the supercharged version, and why they do not supercharge the 7L LS7 in the ZR-1, but instead use the smaller bore 6.2L. They were worried about head gasket integrity.
Other engine design features that can impact head gasket life are if the block is an open deck design (like the subaru 2.5), and if the gasket materials interact poorly with the coolant (like 90's GM v6s with dexcool).
EDIT: here is picture of the deck on a subaru 2.5. Look at how the large bore and the open deck make the contact patch for the head gasket very thin.
Other engine design features that can impact head gasket life are if the block is an open deck design (like the subaru 2.5), and if the gasket materials interact poorly with the coolant (like 90's GM v6s with dexcool).
EDIT: here is picture of the deck on a subaru 2.5. Look at how the large bore and the open deck make the contact patch for the head gasket very thin.
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In case anyone is interested in seeing the comparison, here is the 2.2L subaru block. Same engine family as the 2.5 but the 2.2 has a closed deck and a smaller bore. This engine has basically zero head gasket problems while the 2.5 is notorious for them.
Originally Posted By: ksp7498
The 6-cylinder subarus are fine. It's also suspected that the new subaru FB engine (used in the forester and non-wrx impreza, so far) will be much better as well because it has a smaller bore and longer stroke which makes the gasket thicker between the cylinders.
Just highlighting what you said... and in any properly assembled engine the WIDTH of the gasket won't matter either.
If it did how could my blown big block huff 15 psi with those 4.56 bores? There's very little width of gasket in between them and almost no thickness at all! (It uses a metal HG)
The 6-cylinder subarus are fine. It's also suspected that the new subaru FB engine (used in the forester and non-wrx impreza, so far) will be much better as well because it has a smaller bore and longer stroke which makes the gasket thicker between the cylinders.
Just highlighting what you said... and in any properly assembled engine the WIDTH of the gasket won't matter either.
If it did how could my blown big block huff 15 psi with those 4.56 bores? There's very little width of gasket in between them and almost no thickness at all! (It uses a metal HG)
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Metal head gaskets are stronger but they are not going to come in most cars from the factory. Curiously, this is how subaru tackled the head gasket problem on the turbocharged EJ25 as well. The gasket material choice is yet another good example of an engine design decision that can significantly impact head gasket life.
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