This is not meant to be a scary thread and shouldn't be. One thing I think most can agree on is the bearing is an item that fails in about 1% of dual row cars and 8% of single row. That's enough to prompt some folks to treat the bearing as a maintenance item and change it out.
I thought I'd start this thread to provide those thinking about changing their own IMSB a resource to review to help make the decision whether or not to do it before diving in. I've seen folks not locking at TDC, or (gulp) dropping a fastener into the engine. So if you've changed your IMSB you can help others by posting here, and if you have a thread, include a link! Include the Good, the Bad (true confessions) and the Ugly. Remember, pictures or it didn't happen.
I cheated a little and changed mine while the engine was conveniently split. After lots of study I went back with a Nachi 6204 high temp fully sealed (Viton) steel bearing (about $10) with a couple of small holes drilled in the IMS chain sprocket to stop oil from getting pushed through the bearing. The lower photo shows one of the two holes drilled through the chain sprocket.
The Good, after everything I've read, I'm convinced that the grease will stay in the bearing, and with full seals, bearing killing foreign objects will stay out. Over 4000 miles and it's still running great. I also upgraded the IMSB bolt with the Pelican Parts kit.
The Bad, The repair is totally unproven, far as I know I have the only one.
The Ugly, made my own tools that were barely adequate for the job and I ruined a bearing.
What I'd do different, Get the right tools.
