[Vwdiesel] Is it weird oil pressure?

[Shawn Wright]

On 21 Apr 2005 at 15:47, Libbybapa at wmconnect.com <Libbybapa at wmconnect.com> wrote:

> 
> Actually my TD does not seem to have LOW oil pressure, as I have stated 
> previously.  Even hot at the head never drops below 14 psi at idle.  Cruising is
> 28+ hot.  I am not concerned about the overall amount of oil pressure, but
> rather it's behavior.  It would seem to me, and according to others experience,
> that the oil pressure should be independent of boost pressure.  Mine is not. 
> Oil pressure drops as boost increases.  That seems weird to me.  I have
> previously forgotten to mention that the bahavior is more dramatic when the
> engine is cold (below freezing).  Oil pressure will register 70 psi idling, and
> as one accelerates it will rise normally, when boost starts to kick in it drops
> way down to 5-10 psi.  That is about a 70-80psi drop in oil pressure when the
> turbo spools with cold oil!  When hot and cruising without boost it will
> register 35psi full boost will drop it to 28psi. Any explanations will be
> considered and appreciated. Andrew

Now this triggered a memory for me - mine would sometimes peg my 100psi gauge 
when really cold with 20w50 or 15w40 oil (below or around freezing is really cold 
here...), but only for first few minutes of driving. I do recall seeing the pressure 
suddenly drop as boost kicked in, although I don't think it was as low as 10 psi. Since 
it rarely gets that cold around here, and I need to drive a fair distance before I hit a 
main road, this behaviour was fairly rare. I always assumed it had something to do 
with the oil pressure relief valve.

Shawn Wright
http://zuiko.sls.bc.ca/~swright
'85 Jetta D 
'88 Westy 2.1L, soon to be 1.6TD 5 speed
 (see progress at http://members.shaw.ca/vwdiesels)
'82 Diesel Westy