I bought a used 2005 BMW M3 (E46) With 60K miles wonder about the health of its engine. It has the VANOS system like many BMWs and I have heard it is a common failure point. Outwardly, the engine and VANOS seem ok – drives well at all RPMS, no codes on a scanner, no oil leaks, and no rattle sounds.
How can I tell if the previous owner updated the VANOS (for example Beisan kit) or if it needs maintenance? If I pull the valve cover, are any parts likely to have visible date markers on them?
Hello Mr. Zoghby, in order to check if the VANOS has been upgraded you would have to take it apart, there usually are markings but the parts are internal to the VANOS unit, therefore I think it is not viable due to the labor involved. The other way is to have the records. If there are no issues at this time I would just monitor it. As far as engine health goes I would recommend a leak down test on the engine and a lab test for the engine oil. The leak down test will give you a percentage of cylinder leakage, the way the test works is you have a special set of gauges, you add compressed air to the cylinder when it is at top dead center so that both intake and exhaust valves are closed, one gauge measures how much air goes in, the other measure how mach air stays in, the standard is 10% leakage. If there is any more leakage than that you can hear the air escaping, either from the oil cap, the exhaust or the intake.
The oil lab test will tell you the overall health of the engine, it works much like a blood test, it will tell you if you have any metals, coolant, water, etc… The best way is to have an oil change done, note the oil brand and grade, drive it for 5000 miles or 6 months, at the next oil change take a sample from about he middle of the drain time, the engine has to be hot. Send that out and wait for the results. I like to use Blackstone Labs, the cost is $38.00. Hope that helped, please let me know if you have any other questions. Thank you.