AOS replacement tips

[Qmulus]

I did the AOS on my '03 S (three chain engine) this past weekend. The later AOS mounts differently than the early engines and it was a piece of cake. There are two hex head bolts that mount it to the head from the top, the two snap on PCV fittings, and a spring clamp on the hose underneath (this is in place of the bellows on the previous AOS). On this engine I found that it was easiest to access the hose connections from the top. First I released the plastic snap on fittings, then used a small vice grip pliers to get the spring clip. I left the vice grip on the clamp until the clamp was on the new AOS, then released it. MUCH easier than using a spring clamp pliers. That work was done leaning over from the driver's (left) side of the car. At first I tried to get at it from the right side and from below, but it was easier from the left side. Last I removed the two mounting bolts (working on the right side) from above and pulled it out. That process took me about a half an hour, but I could probably do it in 10 minutes next time. Carefully removing the plastic snap connectors is the toughest part. The car now has 52k miles and from what I can tell, the AOS looked to be original.

My symptoms were an occasional plume of oil smoke at start up, a slight rough idle when cold and intermittent resonance (noise). That all seems to be gone now.

So, if you have a late three chain M96 (M96.24 in my case) don't bother jacking up the car or putting it on a lift to swap the AOS. It is MUCH easier to do it from the top.