An EGR (Exhaust Gas Recirculation) Cooler is a heat exchanger designed to recirculate exhaust back to the engine so as to reduce NOX (Nitrous Oxide) emissions. The EGR cools the exhaust gas before it is reintroduced into the engine, thus reducing the combustion temperature and NOX.
A bad EGR cooler can indicate a number of problems and exhibit a number of symptoms. The symptoms are easy to look for, so use them as a guideline to diagnose the problem. Once you know what the problem is, you can make the repair or take your vehicle to a certified professional automotive technician to take care of it for you.
Symptom 1: Steam
Steam coming out of your exhaust is a good indicator your EGR cooler is bad. At first it may appear to be white smoke, but with closer observation you’ll recognize it as steam, not smoke. You can tell this by the texture, smell and color. There may also be dripping on your exhaust pipe from the condensation of the steam. This occurs from the coolant dumping into the exhaust system and the exhaust system heating the liquid at a high rate, causing steam.
Symptom 2: Coolant Flow
While not an actual symptom of the EGR cooler, if your coolant is coming out of your degas bottle this could indicate a plug in your engine oil cooler that’s causing a restriction in the flow of coolant into your EGR cooler. The steam coming from the degas bottle is caused by the boiling of coolant because the flow of liquid is restricted. Take this opportunity to replace your EGR cooler, because it is likely stressed and worn from the plugged oil cooler and results. If not replaced it will likely fail in the near future, even after you’ve fixed the plugged oil cooler situation.
Symptom 3: Coolant Overflow
Another symptom of a bad EGR cooler is an overflow of coolant out of the degas bottle. You generally notice it by the contact low level of coolant. This can be caused by the overflow in the bottle or coolant system. Ignoring this symptom can be a costly mistake that leads to the other symptoms mentioned. Do not mistake this symptom as a coolant leak.
Once you’ve recognized the symptoms of a bad EGR cooler you need to take a few minutes to diagnose the problem. You can do this with a simple test. First turn off your vehicle and let it cool down. Then remove the EGR valve (it looks like a seven-ounce can and is located by the oil filter and alternator). Use a flashlight to look inside. If it appears to be steamed out, has a thick gooey liquid or residue or is wet, there is a problem.