[ihc] RE: David's "diesel" 258

["Peter Shubin" <pshubin@xxxxxxxxxxxxx>]

My 258 in my Scout made the same noise that David is describing.  I was told
by many familiar with the 258 that it is a common high mileage 258
characteristic.  My 258 ran just fine with the noise right up until I pulled
it and put in the 360.  Now I have a different rumble that comes from under
the hood.


-----Original Message-----
Date: Tue, 17 Aug 2004 10:14:29 -0600
From: "ken.dunnington" <ken.dunnington@domain.elided>
Subject: [ihc] Re: David's "diesel" 258

David Bongo wrote:

DB> The truck runs loud, (258 I-6) but more so at slow speeds.  While the
DB> noise doesn't ever go away, it lessens when accelerating.  Which, as I
DB> understand it, is the opposite of pinging.

David

My *guess* would be that you are hearing piston slap in that 258. This
condition can mimic the noise of a diesel.  If excessive it can cause
damage but generally is only going to cause a loss of efficiency and
longevity.  One way an engine ends up with piston slap is many many
miles so perhaps that is the culprit.  Piston slap is simply a result
of excessive clearance between the piston and cylinder wall.  This can
also be the result of improperly fitted pistons on a new or rebuilt
engine.

Generally, engines can continue in service for quite awhile with
piston slap.

Improperly fitted wrist pins can also exhibit a noise such as this
but this condition will result in failure much sooner than piston
slap will.

Is the diesel-like noise loudest on cold startup?

Ken