|
Premature Chain Stretch from Bad Cam Bearings?
On my 85 380SL, I did the timing chain job at 95K, and had cam bearing failure on the LH cam and bearings at about 106K (not the oil tubes, the engine had a tough life before I bought it, I had to replace the RH cam at 95K, upon purchase, before doing the chain due to a worn lobe). The lower guide broke on the LH side at 119K and I've replaced the LH guides (with METAL guides), the cam gears, the chain, and the tensioner. Originally, I thought the tensioner went bad but I'm guessing that I had 8-10 degrees of stretch and the tensioner was pretty darned close to the limit. You won't believe this, but the e-clips came off (probably due to the broken guide piece bouncing around) and the link and outer plate were being held by a piece of plastic from the guide about 1/4 the size of a grain of rice!
Anyway, after doing this, the new tensioner is much more "pushed in", and the stretch is probably no more than 2-3 degrees. It's hard to say what changing the cam gears was worth out of that improvement - they were scored and definitely sharper than the new ones.
I'm guessing that the bad LH cam bearings (the cam was not spinnable by hand) stretched the chain prematurely.
Does this sound reasonable?
|