Re: 91 200q low oil pressure

["Scott M." <scottmo@teleport.com>]

Jerry,

Regarding your lower oil pressure...

Jerry said:
>   Finally got around to installing second oil cooler per
Eric F.'s 
> suggestion.  Car seems to run a little cooler in normal
street 
> driving, as it appears the thermostats on both open at
relatively the 
> same temp.  

What was your oil temperature running before you added the
second oil cooler? Normally you want the oil temp to get
above 80-85C as quick as possible to avoid sludge formation
etc. The Audi turbo engines routinely run slightly above
130C oil temps with no problem. I suppose if your car is
run on the track at high speeds/high revs for long periods
of time, the oil temp could get excessive especially with a
modified engine/turbo.

>However, at speed,  when warm, oil pressure is down.  Now 
> about 3.25 bar as opposed to 4 bar per guage.  Pegs guage
at 5 when 
> cold and idle is almost the same (difference is the width
of the 
> needle), just under 2 bar.  Other than bigger or longer
hoses, any 
> explanation for pressure drop?

Well, going with a larger hose and/or a longer length hose
normally would result in a pressure drop through the
system. Having 3.25 bar of pressure should be more than
adequate. Is this second oil cooler installed in parallel
with the original stock cooler setup? Is the oil thermostat
on this second cooler designed to open at the same
temperature as the stock oil cooler thermostat? If it is,
when these two t/stats open up, you have got two sets of
lines, coolers etc to pump the oil through which should
cause a drop in pressure with all other things being equal.


I am making the assumption that the stock oil cooler
thermostat causes all the oil from the pump to flow through
the cooler and then back into the engine when the t/stat
fully opens. Does anyone know if this is indeed the way it
operates? It would seem that upgrading the stock size oil
cooler to a larger size cooler would make more sense than
adding a whole separate cooler, thermostat and additional
oil lines especially if the second thermostat opens at the
same temp as the stock oil cooler thermostat. Any ME's out
there who specialize in fluid mechanics?

Scott M.
89 200TQ

> 91 200 STEADIA3qw