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

[David Bongo <dbongo@xxxxxxxxx>]

On Tue, 17 Aug 2004 10:14:29 -0600, ken.dunnington
<ken.dunnington@domain.elided> wrote:
> 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.

The engine was freshly rebuilt just prior to my purchasing the rig. 
So excessive miles wouldn't be the cause.  A poor rebuild is a
possibility, though.  I'll have to get it checked out.

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

That's good news, since I can't afford to have the rig out of
commission for any length of time.  I get Wednesdays off, so anything
that can't be done in one day is cause to burn vacation time.  And,
maybe it's just me, I prefer to use vacation time for, you know,
vacation and stuff.  Auto repair is kinda low on the list...

> 
> 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.
> 

Let's leave it as piston slap, then, OK?  <sigh> I'll have to get that
looked at, as well.

> Is the diesel-like noise loudest on cold startup?

I'm 99% sure (I'll check tomorrow) that it's a bit louder on cold
startup, but not much.  It's why I haven't dismissed the exhaust leak
theory, since it does SEEM to get a tiny bit better when it warms up.

I paid close attention yesterday when I picked up the rig, and I'm not
entirely convinced that it does get less loud when accelerating.  I'm
thinking now that the "diesel" noise is constant, but the other noises
associated with acceleration are louder and, therefore, just drowning
it out.  But it's tough to tell.

Thanks for the help.

Dave