I DID IT! On my beautiful W124 1989 300E (105,000 miles) the belt tensioner unit was shot and I had been planning to do the work for a while. I'd bought the parts through PartsShop (if anyone hasn't ordered stuff from them yet, WHAT ARE YOU WAITING FOR?!?!?) and was waiting for the "right day". The belt was wailing and I kept getting these "if you've got such a nice car, why don't you get it fixed...?" looks.
In the mean time I had done a transmission service on my wife's car ('92 190E 2.3 W201)and ended up over-torqueing the pan bolts and ruining the gasket. Ended up less than a week later having to have the car towed 40 miles ("over the hill from San Jose to Santa Cruz) when the pan gasket failed and spilled most of the new Mobil 1 synthetic ATF all over the parking lot at my wife's workplace. Our mechanics LOUDLY told me never to use ANY synthetic in our cars and said that I was lucky not to have ruined the transmission by botching the job... Needless to say, I was gun-shy in a BIG WAY!
For this reason I kept putting off the tensioner replacement. Yesterday I took a day off from work and made up my mind to do the tensioner job. I'd printed up numerous accounts from this board on how to go about it and I'd printed up the directions from my service and maintenance CD-ROM so I thought I had it in hand. We also have an extra car right now so I figured that I didn't have to rush it and could walk away from it if the thing really got the better of me.
I took my time, looking into all sorts of stuff while I was "in there" and after 5 1/2 hours turned the key - silent, smooth rock-steady purring, just like it should be. I DID IT! I've got to say I had begun to question my ability but as I said, I took the time, made sure to do it right, had the instructions and all of the parts I needed and just got into it.
If you're contemplating a job to keep up "your baby", take your time, have everything in hand before you start and GO FOR IT!
Thanks again PartsShop for saving me around $150 for the parts alone over what the dealer quoted me for this job.
Scotts Valley, CA.
1993 300 CE Cabriolet (A124) 131K miles
1997 C-280 133K miles
2000 BMW R1100RT 69K miles
1989 300 E 216K miles (sold)