“A leak-off test is a specialist test to find the cause of the abnormality. If you find a cylinder with low compression, a leak-off test will tell you why. If air leaks out of the exhaust or intake manifold, a valve is leaking - cylinder head repair required. If it leaks out of the oil cap/PCV system, rings are allowing excessive blow-by” It was leaking pretty bad, so got a new one from dealership, when I went to replace it the old one pulled right out, they stripped the cast aluminum threads so Im screwed for a bit. I temporarily stuck a 7/16x20 bolt with teflon tape in it to stop it from leaking and will be replacing the housing when i do the EGR delete and oil cooler upgrade. The coolant cools the exhaust gases, and this part can crack. If the EGR cooler cracks, it can cause coolant to come into the exhaust pipe and drip from the tailpipe. If the water coming from the tailpipe smells sweet, it could definitely be caused by a broken EGR cooler if your car is equipped with one. 5. Defective Pistons or Rings The 3 Most Common Cummins ISX Problems and Failures. 1. EGR Issues. As we mentioned, the EGR system was a newer addition to the ISX. Like any other engine with an EGR, the system can cause some problems. On the ISX, it most likely has to do with a leak in the EGR valve. This is a difficult problem to diagnose, but monitoring the coolant A large leak diagnostic trouble code is related to, and could also cause, these additional trouble codes: P0440; P0441; P0442; P0444; P0445; And more; Many of these EVAP trouble codes are from a series of sensors that measure different areas for air leaks. A major leak could affect more than one area, causing multiple trouble codes. When a valve cover is bad, you may notice an external oil leak. This would also lead to a lower oil level than expected. Depending on where the oil is leaking, you may also smell something burning. This problem can also cause oil in the spark plug wells, a misfiring engine or dashboard warning lights. The throttle body costs between $200 and $500, while the labor cost is around $50 and $150. The throttle body can be differently priced depending on different vehicles, models, and the manufacturing company. Basically, the main cost involved in replacing a throttle body is the cost of the parts required to be replaced. Engine Overheat. One of the clear signs of a bad EGR cooler is if the engine overheats more than usual. This typically happens if a blockage restricts the exhaust gas flow in the cooler. The jam happens if there is carbon build-up in the cooler after an extended use time. When this happens, the cooler will not efficiently cool down the exhaust Take note though that a faulty coolant container causes smoke to come from the engine, not from the exhaust pipe. 4. Oil Leakage. A faulty valve or piston will cause the oil to leak into the combustion chamber and be burnt together with fuel. With the burning of the mixture, however, blue smoke, instead of whitish, is released. Another possible cause for the P0401 code is a faulty EGR valve. This part can also stick due to carbon buildup, but also wear. It’s recommended to clean the EGR valve every 20,000 miles or replace it if it’s stuck even after a thorough cleaning. Vacuum Hose Leaks. Cracked or leaky vacuum hoses between the EGR valve and EGR control solenoid 9yqB.