Replacing Olds 5.7l diesel head gasket

Dan Youngquist wrote:

> On Mon, 4 Jun 2007, Don wrote:
>
>> It is sheer folly. The diesel version of the Olds 350 engine was an
>> unmitigated disaster. The Olds 350 was designed for 9-10/1 gasoline
>> compression ratios and then a diesel version was hasily conceived with
>> much higher compression and attendant stress. About all they did was
>> increase the head bolts from 7/16' to 1/2' It wasn't enough and the
>> engines blew head gaskets all the time.
>
>
> You're partly right. It's loosely based on the gas 350, but that's not
> necessarily a bad thing if it's done right. GM's big mistake was not
> adding more head bolts, which led to the head gasket problems.

Well, there was another big factor, too. GM put these engines in cars
that were built for gasoline engines and didn't have the added fuel
filtration, water/fuel separation, and general water-vapor resistance
that diesel fuel systems need. Combine that with a Roosa fuel injection
pump that wasn't exactly the most rugged in the world, and you got a lot
of cases of very uneven cylinder fuelling. In other words, a few
cylinders would be trying to produce a lot more power than others, so
the pressures in those cylinders would shoot sky-high and blow gaskets
(or pound bearings, or break pistons). Attentive owners who could have
recognized the sounds of uneven fuelling would have helped too, but
diesels were a very new thing to most consumers back then and many
owners simply didn't know the engine wasn't running right until the
damage was done.