How to Avoid a Blown Head Gasket
(GM 4.3L, 5.0L, 5.7L)

How to Avoid a Blown Head Gasket

Is it possible to avoid a blown head gasket on your 4.3L, 5.0L, or 5.7L pick up (SUV, van or mini-van)? The answer is: Yes, you can avoid a blown head gasket on your vehicle by taking some simple precautions.

In this article I'll go into some detail about what you need to do, to avoid the tremendous expense that's involved with having to replace blown head gaskets.

The Root Cause of a Blown Head Gasket

The most important thing to keep in mind, is that a blown head gasket is usually caused by two specific things:

  1. Severe overheating. Usually the result of:
    1. Water pump failure.
    2. Coolant thermostat failure.
    3. Radiator Hose busting open.
    4. Radiator busting open.
  2. Internal hot spot developing on the engine block deck due to a small coolant leak preventing the cooling system from pressurizing.
    1. This little coolant leak usually doesn't cause the engine to overheat... which leads a lot of folks to just ignore it and think it's just ok to keep adding water or coolant to the radiator.

Now, in case you're wondering what the heck is the 'engine block deck'... this is the top surface of the engine block that mates with the cylinder head via a head gasket.

Of course, a small coolant leak doesn't result in a blown head gasket overnight... but ignored long enough, this little leak will eventually result in a blown head gasket (I've seen this happen a lot!) Why? because the cooling system needs to pressurize to a certain pressure to effectively keep the engine at a normal operating temperature. If it doesn't pressurize... the engine develops internal hot spots that can crack heads, the engine block, and burn head gaskets!

OK, in the next couple of sub-headings, I'll go into more detail on the things you need to keep an eye out for and repair and/or replace as soon as you spot a problem.

The Most Important Thing
You Can Do Is To Check For Coolant Leaks

Regularly popping open the hood of your pickup, van, or SUV and checking for coolant leaks with a flash light is fast, easy and important... especially if your vehicle has a lot of miles on it.

What do I mean by 'regularly'? Well, I recommend checking under the hood for coolant leaks at least once every two weeks or worst case... once a month. This is especially important if you have already replaced anything under the hood that required removing a radiator hose, the water pump, intake manifold, etc.

Also, scanning your driveway (or garage, if you park your vehicle in a garage) for green coolant puddles (or orange coolant puddles, if you have Dex-Cool in the radiator) whenever you pull in or out will go along way to finding coolant leaks.

Another good time to check for coolant leaks is at oil change time (whether you do them yourself or take it to a fast-lube/oil-change place). Since you're already under the hood (and under the engine draining the oil and replacing the oil filter), take the time to thoroughly check the top and bottom of the engine area for coolant leaks with a flashlight.

Although the following is not an exhaustive list of things that can leak coolant, it'll give you an idea what to shine your flashlight on (while you're under the hood or under the vehicle):

  1. Radiator Hoses (where the hose is clamped to the radiator or the engine).
  2. Heater Core.
    1. Since the heater core is inside the vehicle, the areas you need to check for coolant leaks are the front passenger side floorboard (inside the vehicle) and by the lower-bottom part of the engine's firewall.
  3. Radiator.
  4. Radiator cap.
  5. Intake Manifold Gaskets (the geniuses at GM decided to use plastic intake manifold gaskets that are prone to breakage around the coolant ports and are infamous for coolant leaks on the vortec 4.3L, 5.0L, and 5.7L engines).
  6. Water Pump weep hole.

If you do spot a coolant leak, what next? Well, let's explore this in the next subheading...

Don't Use Leak Sealers to Stop a Leak

If you do spot a leak, one of the worst things you can do (for the long run) is to use a coolant leak sealer to stop a leak! Whatever is leaking coolant needs to be replaced!

Yes, I know it's so tempting to use some sort of stop leak in a can because depending on what's leaking... it can get expensive once you factor in the parts and the labor (if you're not doing the job yourself) to fix the leak. Not only that, but the kid at your local auto parts store swears by the can of "Magic Coolant Leak Plugger" as being cheap, safe, and effective.

Well, simply put, a can of stop leak may work initially to stop a small coolant leak, but it's not a permanent repair. To add insult to injury, this can of stop leak will help clog your heater core and radiator in the long run and eventually cause your vehicle to overheat.

So, eventually, not only will you have to repair the leak by replacing the part that's leaking coolant, but you may also have to either rod-out the radiator (or replace it) and replace the heater core, thus making this 'cheap fix in a can' an expensive one!

How do I know a can of stop leak is more trouble than advertised? Well, I've been working in the trenches of automotive repair as a full time tech for 20 years now and have seen first hand its ineffectiveness (not to mention its surpassing ability to cause the vehicle owner to spend more money down the road). So, my advice to you is: avoid the can of coolant stop leak and replace the component that's leaking.

Replace the Thermostat as Part of Regular Maintenance

You're already used to replacing quite a few things on a regular basis such as: engine oil and oil filter, air filter, brakes, belts, ignition system components, etc., so... why do we neglect something as cheap as a thermostat?

It may very well be due to the fact that the thermostat is simply out of sight inside its housing that we simply don't give the thermostat any thought (as the ole’ saying goes: “Out of sight, out of mind”).

Well, changing the thermostat at least once every 30,000 miles should be done as routine maintenance, considering the importance of the thermostat in keeping the engine at the correct operating temperature.

Keep in mind that the thermostat isn't going to last forever and when it does go bad, it usually stays stuck closed (although in rare occasions, it stays stuck open when it fails). The end result is the engine overheating. As you've learned so far, overheating is the number one cause of a blown head gasket.

If the Vehicle Overheats on the Road

Most of the head gasket repair jobs that have been assigned to me (at work over the years) usually resulted from the customer noticing that his/her vehicle was overheating, but decided to drive it as far as it would go. A thousand dollars plus later, he/she realized that maybe it would've been better to pull over in safe/public place and have a tow truck tow it to the shop.

There are so many factors involved in deciding to pull over and have it towed home or to the shop, when a vehicle overheats. Things like: Is it a safe area? The weather (rain, snow, cold, heat, etc.), how far you're from home, etc.

But, once your vehicle starts to overheat, every mile further down the road you drive it... is possibly adding more money to the final repair price. Not only that, the engine will eventually just stop (stall). So it's better for you to decide to pull over in a safe, public and well lit place and wait for the tow truck, than to have the engine blow a head gasket and quit on you in the most inopportune time and place.

Maintenance is Key to Preventing a Blown Head Gasket

Maintenance involves time, effort and the five letter dirty word: money. There's just no way around this... but considering just how expensive it is to have the head gaskets (and possibly the cylinder heads) replaced... the cost of preventive maintenance is far cheaper.

Remember, it is possible to prevent a blown head gasket on your GM 4.3L, 5.0L, or 5.7L equipped pick up, van or SUV if you check for coolant leaks, repair coolant leaks as soon as you spot them (avoiding stop leak in a can fixes), replacing the thermostat as part of routine maintenance, and if your vehicle does overheat... stop in a safe place and have it towed home or to the shop.

Chevrolet Vehicles:

  • Astro
    • 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
  • Blazer
    • 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
  • Blazer TrailBlazer
    • 1999, 2000, 2001

Chevrolet Vehicles:

  • C1500, C2500, C3500 Pick Up
    • 1996, 1997, 1998, 1999, 2000
  • Express Van 1500, 2500, 3500
    • 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
  • G30 Van
    • 1996
  • K1500, K2500, K3500 Pick Up
    • 1996, 1997, 1998, 1999, 2000

Chevrolet Vehicles:

  • K1500, K2500 Suburban
    • 1996, 1997, 1998, 1999
  • P30 Van
    • 1996, 1997, 1998, 1999
  • S10 Blazer
    • 1994
  • S10 Pick Up
    • 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004

Chevrolet Vehicles:

  • Silverado 1500 Pick Up
    • 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2007
  • Tahoe
    • 1996, 1997, 1998, 1999, 2000

GMC Vehicles:

  • Sierra C1500, C2500, C3500
    • 1996, 1997, 1998, 1999, 2000

GMC Vehicles:

  • Suburban C1500, C2500
    • 1996, 1997, 1998, 1999
  • G3500 Van & Vandura
    • 1996
  • Jimmy & Envoy
    • 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
  • K1500, K2500, K3500 Sierra
    • 1996, 1997, 1998, 1999, 2000

GMC Vehicles:

  • P3500 Van
    • 1996, 1997, 1998, 1999
  • S15 Jimmy
    • 1994
  • Safari
    • 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005

GMC Vehicles:

  • Savana Van 1500, 2500, 3500
    • 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
  • Sonoma
    • 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004

GMC Vehicles:

  • Yukon
    • 1996, 1997, 1998, 1999, 2000, 2001, 2002

Isuzu Vehicles:

  • Hombre
    • 1997, 1998, 1999, 2000

Oldsmobile Vehicles:

  • Bravada
    • 1996, 1997, 1998, 1999, 2000, 2001

Cadillac Vehicles:

  • Escalade
    • 1999, 2000

“I love deadlines. I like the whooshing sound they make as they fly by.”
Douglas Adams

MORE TUTORIALS: