Re: Engine Knock Right at Engine Start only!!

On May 5, 1:07=A0am, "Dunamis" <u43397@[EMAIL PROTECTED]
> wrote:
> I'm trying to get as much research for this as I possibly can before
takin=
g
> action. Any info you guys could provide would be greatly appreciated!
>
> My Situation:
>
> Sometimes when I go to start my truck, I will turn the engine over and
whe=
n
> it fires up there are a series of 4 knocks and then it goes away. Each
and=

> every time it does it, it's four knocks. It usually happens after the
engi=
ne
> has been sitting for the night. I took my truck to a mechanic concerning
t=
his
> "knock". He said it sounded like front/rear main bearings or possibly
the
> crank shaft, but he could not tell which area it came from. What puzzled
h=
im
> is that it only "knocked" four times and then went away. After that,
> everything sounded perfect. Absolutely NO ENGINE NOISE WHAT SO EVER. He
> commented that the truck ran remarkably well.
>
> Info I recieved from another forum:
>
> this is most likely a problem with the crankshaft main bearings. general
> motors had a bulletin on this when these engines were new and the fix
was =
to
> measure the main bearings and install oversized bearings on the mains.
the=
y
> also note that this will not affect the longevity of the engine. bottom
li=
ne
> is leave it alone.
>
> Do you guys concur with this response?
>
> Thank you for your input!
>
> Phil


Sounds like classic bearing rattle to me. You get it at startup till
the pressure builds up.

Longevity? Hard to say. Were it me, Id think about using a heavier oil
and see if that helps any.
Maybe a can of oil treatment. You want to prevent the rattle. I have
to assume when it rattles it is potentially scarring the bearing. For
putting around town you may get by for a long time, Id be afraid to
make any long distance trips.

Id also think twice before I gunned it to get around grandpa.