Volkswagen TDI Camshaft Warning Signs
The replacement of a Volkswagen camshaft is an expensive item. The part itself is around $700. when VW made the 2004-06 TDI cars (an other years) some experts claim the cam design has a design flaw that causes premature wear of the cam lobes even if the correct oil specification ( 5w40, 505.01) is used over time. Some owners have had to replace a cam under 100K, which in other cars, is not needed. Part of the problem also deals with using less hardened metal technology to make the OEM cams. The OEM cams have a shallow hardness that grinds away over time. Using the correct oil will help but to expect the cam to last for the life of the car or 250K miles is not possible. KermaTDI offers a OEM cam that is optimized and with more hardening depth allowing a guarantee of 300K miles before replacement is needed.
The first sign is akin to detecting cancer. It is finding some soot (black powder-like) in your air filter, yet, the car seems to start and run just fine. This is an indication that some lobe's on the cam are wearing out of spec and allowing some exhaust to enter the air filter. If just a little black soot is present, it may mean only one of the cam's lobes is worn reducing the lift needed for the exhaust valve that allows exhaust to go where it is supposed to go. If the air filter is more extensively contaminated, it means more than one of the lobes are worn. AS the conditions worsens, your engine light will come on show MAF codes showing an implausible signal or odd results. You may think you need to replace the MAF sensor.
As you continue to drive with little more indication of a problem, because the exhaust cannot fully exit the combustion chamber, there is a little reverse flow back into the intake valve when it reopens. Over time, this will create a hole in the lifter. The hole disables the lifter's ability to open the exhaust valve. In a four cylinder TDI engine, you now only have three cylinders to run on and you definitely notice the loss of power and compression. The car may backfire, may have starting problems, idle may be rough or shaking. If the engine starts making a ticking or tapping noise, STOP!, once the lifter is worn through, the next thing that happens is the plunger from the lifter ruins the valve stem.
So, some cam wear could wear off .24" from the lobe and the car could still be driveable with obvious problems. Soot in your air filter is the early warning sign that you have cam wear. It could be months after its discovery that more serious performance issues appear, depending how much you drive. VW could have made the cam to last over 100K, and some do, but they chose to reduce manufacturing costs. Also, the cams require the use of the correct oil all the time. For instance, tests show using 5w30, 505.01, will cause wear on the lobes, while 5w40, 505.01, will not. If the oil is used correctly for the life of the car, a cam could last over 200K miles. But, the problem is that when you take the car into for an oil change, you do not know if they actually used the 5w40 versus 5w30. If they use 5w30, you drive another 5-10,000 miles causing damage to the cam lobe and over a few oil changes, the expensive cam replacement will have to occur!