How to Test for Car Exhaust Manifold Leaks

For many, the need to find car exhaust manifold leaks follows a failed emissions test. You might also hear a rumble when starting your car or while it runs cold. Thankfully, finding out whether you do, in fact, have a leak is a fairly easy process.

Step 1 - Test your car shortly after starting it. You may be able to hear and feel the leak more easily while it is still cold. You also lower the risk of burning yourself.

Step 2 - Sniff around for exhaust. This is the least definitive way to test your manifold for leaks, but it may be a sign. Carbon monoxide, which is what is released by your exhaust system, has no smell.

Step 3 - Listen to your car. Most exhaust manifold cracks or leaks will cause a ticking noise, especially when your car is running cold. There may even be a noticeable vibration that goes along with the noise.

Step 4 - Use a stethoscope to listen to the manifold closely. You should be able to determine the location of the leak if there is one. If you don't have a stethoscope, use a hose or tube to localize sound.

Step 5 - Check your manifold physically. If you can get it out of your car and manually inspect the part, you may be able to determine warping or cracking. Since this requires removing parts from your engine, you may want to consult a mechanic.

Step 6 - Look for damage around the exhaust ports. Discoloration or burnt paint often signifies a leak. Burned spark plugs, boots or valves indicate a leak as well. If you notice this kind of damage, have your manifold fixed immediately to avoid more serious fires.

Step 7 - Take your car in for an emissions test, even if it is not due. Most leaks reduce the oxygen output and will cause the car to fail the test. If your manifold passes inspections, you may just need to have it straightened out due to warping.

TIPS: Test for hot spots around joints. Heat escaping the joints is a sure sign of a leak. This kind of leak causes the same effects as a manifold leak. Don't ignore check engine lights on newer cars. Since the oxygen indicator is located near the manifold, the light may be your first sign of a leak.

THINGS YOU'LL NEED: Mechanic's stethoscope

WARNINGS: Even a small leak causes adverse reactions to those in the car. Nausea, dizziness and headaches may occur with carbon monoxide leaking into a car's interior.

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