replace bearings or buy an exchange engine

[mnrumpole]

Hi, Have 92 seville with 245M on it. Main bearing(s) starting to go and like to know cost of replacing bearings vs. buying an exchange engine. I have the large block; like the car, still gets me 28 mpg highway.

[DFBonnett]

What kind of a sound are you hearing? When are you hearing it? The 4.9 engines sometimes have something called "main bearing thump" which is annoying but not indicative of failure. You can test by relieving tension on the srp belt tensioner. If the noise goes away it is that thump. There is a replacement part to attend to this. That being said, 245K is a lot of miles.

[mnrumpole]

the sound is like a bowling ball hitting a wood floor, it happens sometimes when it starts, and most of the time just once, sometimes twice but the second one is softer

[DFBonnett]

That sounds like it could be the engine moving up under torque then dropping down due to a bad motor mount. It doesn't sound like bad bearings.