I recently bought an '89 B250 with the port-injected 360 gas engine. The van
is in nice shape, and seems to have plenty of pep. Problem is -- low oil
pressure. I replaced the oil pump with a new hi-volume one, and installed a
good mechanical oil pressure gauge. It would read around 60psi when I first
started it, then, after 15 miles, if I came to a stop with the transmission
in gear, it would be down to 20psi, and after another 25 miles or so, if I
came to a stop, pressure would drop to zero and the van would stall.

I tried replacing the oil with 20W50 synthetic, and that's helped a bit.
After extended driving, it now only goes down as far as 20psi (again, trans
in gear, foot on brake).

My mechanic says I shouldn't drive it with that heavy oil during the winter,
and recommends replacing the engine bearings. He says he can put them in
from the bottom without pulling the engine, so it shouldn't be TOO
expensive.

I don't mind spending the money, but don't want to spend the money and find
myself in the same situation when we put it all back together.  I've never
put new bearings into an engine without simultaneously cutting the crank, so
I'm not sure if just replacing the bearings is really sound practice.

Thanks.

Joe