Re: tapping sound on startup 93 90q

[Elliott Potter <epotter@abraxis.com>]

>I have a 93 90scq with the 2.8l v6 and when i start it from dead cold it
>makes a sound almost like the valves are rattling. This sound goes away
>about thirty seconds after startup and doesn't come back until i leave it
>overnight. My oil pressure (when cold) stays at 5bars, is that where it
>should be? when it warms up the oil pressure comes down to 2bars and stays
>there until i rev it up, at highway speeds (3000 rpm) it stays at
>5 bar. this seems a little high to me . if anyone has any ideas please feel
>free to voice them. Thank you all.
>                                                                Paul >Dansereau
>                                                               93 90csq
>

Could it possibly be that one of the lines that circulates oil up to the
lifters is partially plugged?  If this was the case then when you
started up the car, the oil pump would pump its regular amount of oil
but with the constriction in the line pressure would build up.  As the
engine warms up, the oil would get a little thinner and find its way
past the constriction, allowing better lubrication and therefore less
noise (and since the oil can move through, lower pressure).  When you
rev it up, the oil pump moves faster, but the oil can't get around the
constriction much faster, hence the renewed pressure build up.  Probably
a little more lifter noise too, but less audible because of other
noises.
Such a blockage might be in one of the lines that take oil up to the top
of the engine, or in the pickup screen (small screen filter at the end
of the intake to the oil pump that rests in the oil pan--isn't there
one?)

Of course all of this makes sense to me but it's also 2:00am so one
never knows.  Sorry if I'm just babbling.



HTH!

Elliott