Hey guys,

I've had a 1990 240DL wagon for 2-1/2 years now. It had a bit of rod bearing noise when I bought it and I've put about 15k miles on it since. Steadily, it's been getting worse so I'm planning for my next steps. I'm going to get in and use plastigage to measure the con rod and main bearing clearances. I'm going to look at the bearings and try to determine the cause(s) of failure. I suspect the cause has been coked up oil from the prior owner not changing oil in time. From there I'll have to make a judgment call as to my next steps.

My options are:

1) Providing all measurements of the crank's rod journals are within book specs: Replacing (at the very least) the con rod bearings and the oil pump. I can check the main bearings and make a judgment call while I'm in there too. Can I successfully clean out the oil passages from the pump to the crank so this doesn't happen again? I've heard of people replacing bearings in-situ: some are successful and many others are not. I'm guessing this is because they don't do clean work and they don't fix the SOURCE of the problem. How would I successfully get through all the oil passages? Let's say I just did the con rod bearings b/c the mains were within specs and looked good: Can I clean the passages in the crank throws only? In parts cost, this is already pushing $300.

2) swap in a used junkyard engine or engine & trans (if possible). This option is going to cost me from $300 to $900 just for the motor or motor/trans. On the plus side, I will have a spare eng/trans to rebuild later if I want.

How concerned should I be about compatibility issues if I'm going to swap in a junkyard eng/trans? I'm going to be looking for a late (post 1989) B230F. Can it come from a 740? If so, what years are valid? Anything to look for?

3) should I attempt a full engine rebuild myself? This would be a lot of fun, but is it going to run me over $1000? Lots of machining and new parts to buy for this.

So what would you guys do? I'd really like to hear from someone who has successfully replaced rod and main bearings. Honestly, if I can get 50k miles out of new bearings I'll really be happy! Any thoughts?

thanks guys!
Steve