I have written plenty of articles on making sure you have the correct amount of fluid in your engine, transmission and cooling system. Yet I don’t think I have ever written one about having too much fluid. Until now.
A customer recently brought in his 2010 Toyota Camry and said that after another shop worked on it, he noticed white smoke coming out of his tailpipe on hard acceleration. He also reported that when accelerating, the car hesitated and had less power. He added that it happened on the freeway more than on city streets.
The problems occurred soon after the other shop performed a brake fluid exchange and coolant service and replaced the spark plugs. The customer was convinced that the white smoke was from engine coolant and the other shop had done something wrong when performing the coolant service.
First, we connected the scanner and pulled diagnostic trouble codes; there were no codes in the powertrain control modules. We then inspected the engine cooling system. The engine coolant level was slighting below the max line in the expansion tank and the radiator was full. We pressure-tested the cooling system and did not find any leaks. The brake fluid was full, as was the transmission fluid.
When we pulled the engine dipstick, we noticed that the amount of oil exceeded the max mark by approximately 4 inches. We lifted the car and performed an inspection of the engine bay. We found that there was engine oil all over the bottom of the intake manifold, positive crankcase valve (PCV) and PCV hose. The PCV hose was bloated and oil damaged.
Let’s get caught up on an engine PCV/crankcase breather system. Every time the piston goes through its four strokes, it pushes a small amount of pressure into the crankcase (approximately 4-6 psi). If this pressure is not vented, it will build up and blow the seals out the side of the engine.
This is where the PCV/breather system comes into play. The liquid oil, oil vapors, unburnt fuel vapors and solids get vented through the breather hoses, PCV valve and breather case. Once this material is in the breather box (breather valve, oil separator, breather case), it is separated into solids and vapors. The vapors go into the intake and the solids go back to the oil pan. This system was designed to mitigate pollutants from getting into the atmosphere and to reburn unburnt fuel.
We removed the excess oil from the engine and found that it was overfilled by 2.3 quarts. If the engine oil is overfilled, several negative things can happen. If the engine is extremely overfilled, it can bend piston rods, displace valve stem seals, overwhelm the breather system, aerate the engine oil and blow cam or crank seals out of the engine. If the engine is overfilled by 2 or 3 quarts, it can overwhelm the breather system and start pushing oil into the intake and/or exhaust. This will in turn cause the engine to start burning a lot of oil in the combustion chamber and foul the engine.
The breather system being overwhelmed with engine oil is what caused the exhaust smoke and hesitation on our customers’ vehicle.
When explaining this problem to the customer, he stated that the last shop did not perform the oil change. He said he took it to a different shop because it was cheaper. This customer only drives approximately 3,000 miles a year and almost never on the freeway. He had the oil changed in January, but then took the car to a different shop in February for other work. The customer had lightly driven the car between the last two service appointments. By the time he got the car to us, the overfilled engine oil problem revealed itself.
We then removed the intake manifold and let the oil drain out. We replaced the PCV valve, PCV hose and related gaskets. We made sure the engine oil was correct and test-drove the car. All was good. We asked the customer to bring the car back after 1,000 miles so we could check for leaks and make sure the engine wasn’t burning any oil. There is still the possibility that the engine could be more severely damaged from the oil level being too high.
There are two lessons to learn from this. First, always check or have your fluid levels checked properly. Second, once you find a good auto repair shop, stick with it. Don’t chase the inexpensive estimate.
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