Durametric Cam Deviation Help

[adbm3]

Thought I'd re post this in its own topic to see about getting some traction (heh)

Fooled around with the Durametric recently looking at the cam shaft deviation on my 2000 S. I just finished changing the belt and had some extra time on my hands.

Cam shaft 2 deviation stayed at -4.89 from cold to full operating temperature. However, Cam Shaft 1 deviation started out at -4.81 and then dropped to -3.81 as the engine warmed up to operating temperature. This change was not at all erratic. In fact, it only dropped by a few hundredths after each rev of the engine via the pedal and then stayed steady until I revved the engine again. I stopped reading the drop after the car hit full warm so I have no idea how low it would have dropped thereafter.

This doesn't strike me as problematic - only the timing changing to maximize engine efficiency as temperature rises. But, would like a more expert opinion.

[JFP in PA]

Probably the result of a worn tensioner tightening up as the oil warms up. I would not be overly concerned, but PCNA has released updated tensioners that use an assist spring to help hold tension as the oil pressure comes up, you may want to look into them down the road.

[adbm3]

Thanks much. I figured that the tensioners were maybe a bit off before I ran the analysis since I get a bit of rattle on cold start. I read up on the replacement procedure in the "101" book and it doesn't appear that bank 1 (left side facing forward from rear, which I believe is cylinders 1-3) is very difficult. Its nice to know that the cam shaft deviation plot on the Duarmetric can also be used for this diagnosis.

[The Radium King]

another good indicator is your oil filter. bits of the plastic chain tensioner ramps will show up there as small, dark brown bits of plastic. There are some good images of this on 986forum. some suggest a heavier cold weight oil (i.e., a 5wxx instead of a 0wxx) so that the ramps retain a bit of lubrication on cold start (the thicker cold weight oil doesn't all run down into the sump); LNE (makers of the billet chain tensioner) recommend 5w40, and porsche now has more 5wxx than 0wxx on their lsit of approved oils.

[adbm3]

That's good advice. Actually, I've been running Amsoil 5w-40 European Formula oil since I got the car. I figured that with all the talk of IMS issues, especially related to seal breakdown and the dogmatic belief of running Mobil 1 0w-40, that there was something a bit more systemic to the issue. Not knocking Mobil 1 but there is the off chance that it has additives or carries contaminants in a way that isn't friendly to the bearing. Just a theory. Besides, I've been using Amsoil in my M3 for over 10 years with no issues.