Elementary, My Dear Watson
Now that you know the causes of leaks, as well as the stakes involved, it’s time to get on to the detection of those leaks.
Fundamentally, if your gasket is leaking, you’ll have one of two things. Either an internal or an external one. The external leak is by far the easiest to diagnose. If nothing else, the large puddle of coolant spreading from under your car should be a hint. A few minutes with a flashlight should be enough to verify that.
But what if the leak isn’t where the naked eye can see it? What if it’s an internal leak?
What then?
An Inside Job
Again, we can divide the types of leaks into two; a leak into an oil galley, or a leak into a combustion chamber.
Should your coolant begin leaking into an oil galley, it only takes a few tablespoons of coolant to destroy your oil’s ability to lubricate engine parts, destroying bearings in a matter of miles. Fortunately, diagnosing this can be as easy as checking your oil. Just pull out your dipstick. What you’re looking for here are thick oil, and a milky white residue on the underside of the fill cap. Either of these can be a sign that you’ve got a leak.
The Heat is On
That was easy enough. Unfortunately, our next suspect is a much sneakier customer. A coolant leak into a combustion chamber can be extremely difficult to diagnose. Yet again though, we find ourselves with two choices at this juncture. When a hole opens between two places, something’s going somewhere.
First up is a leak into the combustion chamber. Coolant leaking into the combustion chamber will cause thick white smoke to come out of the exhaust pipe, a telltale sign. If nothing else, you’ll know that something ain’t right.
But that scenario is as easy to diagnose as it is rare. Unfortunately, you’re far more likely to have combustion gasses leaking into your cooling system. You see, the average car’s cooling system operates at a compression of about 15 – 18 psi. Running compression on that same average engine however, is far higher; 80 – 90 psi. That much pressure difference means that the combustion gasses are much more likely to wend their merry way into your cooling system then not. As these gasses are extremely hot, it doesn’t take a professional mechanic to figure out how well they fit in a system that’s meant to cool the car. In a word, poorly. They heat up the coolant, robbing it of its cooling power. Not only that, but combustion gasses are just that, gasses. On the other hand, coolant fluid is, well, fluid. And what happens when you inject gas into a liquid? That’s right, they form bubbles. Now we’ve got bubbles of hot gasses forming in your cooling system, making the cooling system’s job all the harder.
But that’s not all. Remember that 60 – 70 psi difference between your combustion chamber and cooling system? The one that’s pushing hot gasses into said cooling system? What do you think that much pressure is doing to it? The short answer is: nothing good. The still-short-but-accompanied-by-an-amusing-visual-image answer is to imagine what happens when you hook up an air hose to a regular latex balloon. You put that much pressure into a system that wasn’t designed to take it, and things start breaking. Things like hoses. And radiators. Bad news.