GM's 3.4L, gasket problems


Apr 12, 2006


The Bottom Line Check your lower intake manifold gasket at every oil change, and get the most up-to-date one installed if it's leaking.

Introduction
If you've been following the news lately, you would have heard about the lower intake manifold gasket problems with GM's 3.4L V6 engines. I am not a spokesperson for GM, nor did they pay me to write this article; however, I am an owner of a GM vehicle with this engine, I have experienced failure of the lower intake manifold gasket, and I have done extensive research on this problem. In this article, I will explain why I switched from driving an import to a GM, then I will go into details on this problem.

My Honda
Back in the early 1990's, the general attitude about cars was that domestic was crap, and imports, in particular Honda, were superior automobiles. I bought into this import hype when I bought a used Honda Accord. I was extremely happy with this car until one fateful day it unexpectedly died on a long stretch of backroad, leaving me stranded. Personal cell phones weren't popular until the mid-90's, so I had a heck of a walk. I had the car towed to a shop, where it was determined that the timing belt broke. I was reasonably familiar with automobile mechanics and could not see any broken belts, then it was shown to me that this belt was hidden. What's worse, when it broke, it actually caused the engine to self-destruct! Valves crashed into the pistons, damaging both the valves and pistons. I could not believe that my Honda was so fragile! The repair cost was crippling; I basically needed a new engine.

GM convert
The woman who would become my wfe was driving a '93 Cavalier. I was paranoid about timing belts, so I went with her when she took it to the dealership for an oil change and asked them about it. That's when they told me that the engine didn't have a timing belt! In fact, most of GM's engines do not have a timing belt. To drive the accessories, they used a self-adjusting heavy duty serpentine belt that lasts a long, long time. The car drove quite smooth, was reasonably fuel efficent, and had plenty of power. It occurred to me that GM's focus was on making the engine as maintenance-free as possible; this became more evident as they started using Dex-Cool engine coolant, platinum spark plugs, and then incorporated an engine oil life monitor. That car turned out to be the most reliable car I've ever seen, with the lowest maintenance cost. It was so good, her sister bought a '95 Cavalier which was also extremely low maintenance. I was forced to re-evaluate my perceptions, and came to the realization that GM was one of the, if not the, best automaker in the industry for people looking for a low maintenance car.

What is a gasket?
Gaskets are material that seals two metal surfaces together. They can be made of cork, silicone, metal, rubber, or a combination of materials, depending on the task they're required to perform. In a car engine, gaskets are usually under extreme heat and pressure demands. It's not uncommon for gaskets to fail in a car; indeed, all cars will experience some kind of gasket failure at some point, due to the fact that gaskets break down over time due to the extremes they're placed under. However, we have come to expect critical gaskets to last 10 years or more under normal driving conditions. Critical gaskets are those that are necessary for the car to operate without catastrophic failure.

What's the big deal about the lower intake manifold gasket?
The lower intake manifold gasket has a very demanding job; it needs to keep the coolant and oil from mixing with each other. Coolant and oil are under pressure, and both get very hot. If this gasket fails, it may be possible that coolant, being under higher pressure than the oil, can get into the oil system. When coolant gets into the oil, the oil can't do its job properly. This can possibly lead to catastrophic failure of the engine if the leak isn't detected in time. Fortunately for owners of GM's 3.4L engine, it's usually easy to check and see if this gasket has failed before catastrophic failure, as oil will seep past the gasket and be visable.

Why do gaskets fail?
In spite of our best efforts, gaskets can and do fail. It was a gasket failure that caused a space shuttle to explode, in spite of the best efforts of the best scientists and engineers at NASA. They fail because, over a period of time, we cannot always predict unforseeables; engineers can test a gasket on an engine and run it day and night to simulate hundreds of thousands of miles, but it's humanly impossible to predict what will happen in unique situations or over an extended period of time. In the case of the lower intake manifold gasket, some people suspected that the long life engine coolant caused the gasket to deteriorate as its chemical composition changed over time. Others feel that the gasket was too thin and eventually collapsed. Indeed, advances in engine fluid technology almost always comes with unforseen consequences, and it always seems to be the gaskets that go. For instance, in the 1970's, it was discovered that synthetic oil, while superior to conventional motor oil, caused gaskets to shrink.

I have a 3.4; How do I protect myself?
The best way to protect yourself is to keep an eye on the intake manifold gasket. Based on my experience, it doesn't fail instantly, unexpectedly, and catastrophically like a timing belt will, but rather will start to seep oil visably for quite a while before coolant starts to slowly seep into the oil; so I would think that checking it at every oil change for seepage ought to be sufficent. If you know your way around an engine bay, the intake manifold is on the side of the engine that's at the front of the car. If you can't tell the difference between an intake manifold and the oil pan, most competent mechanics know what to look for. The dealership I go to, Cliff Mills, checked for this problem for me for free.

This has been a problem since 2001, what gives?
Reports indicate that GM recognized this problem as far back as 2001, and now it's 2006. Consider that the 3.4L started to be widely used in 1998 for the '99 model year line-up, and we're looking at roughly 3 years minimum before gasket failure. My car, a 2002, took four years before this gasket showed signs of failure. Cars are usually manufactured a year ahead of their release date. We can then assume that, given the 3-4 year time span for gasket failure, GM would recognize this as a problem sometime in 2002. By then, they're already manufacturing cars for 2003. I doubt even the best engineers can redesign a gasket overnight. At the same time, they can't exactly shut down production because of a gasket failure.

Have they fixed this problem yet?
It appears that GM has addressed this problem on three fronts. One, they've ceased using the 3.4L engine alltogether; it's been replaced by an all new 3.5L engine. Two; they now offer a 5 year warranty instead of a 3 year warranty, which would be plenty long enough to cover this type of failure. Three; the new gasket looks a lot more substantial than the old one. I'm told that it's also impregnated with silicone, which has amazing properties. Based on this, I would say that, yes, it does appear that this problem has been corrected.

Mine went outside of warranty, what do I do?
I don't represent GM, but I do recognize the value of the extended warranty. GM offers, and people buy, the extended warranty because of unforeseeables such as gasket failure. That said, if yours failed and you're just outside of your warranty, I'd give them a call. My experience with them thus far has been positive, like they actually care about the customer. Indeed, I've seen them go well out of their way to ensure customer satisfaction. Also, it should be noted that their new vehicles now have a 5 year warranty, which should reassure people considering a new GM vehicle.

Conclusion
I still maintain that GM vehicles are some of the lowest maintenance vehicles in their respective classes. This gasket failure appears to be a snag on their road towards a completely maintenance-free car. Keep an eye on yours, and if it does start to leak, make sure to get the most up-to-date gasket installed.

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