Low oil pressure?

[w00zie]

Wondering if i've got an issue or not......

In the past, all the 911's i've owned have had high oil pressure at start up (goes to 5, idle @ 3),,,,not a concern

But lately when my oil temp hits 200/210/220, @ full throttle i'm ok and hitting 4-4.8. But at idle (750 RPM) my oil pressure sits at 0.75, just a bit under 1

Of all the cars i've had, the lowest i've idled at is 1. I've had this car for a long time, and i'm at 51,000 miles. I had an issue with oil pressure on the top end before but it ended up being a sending unit which was replaced about a year ago

My 993 has over 60,000 miles and idles @ 1+

I'm wondering if i should be concerned. Any input would be appreciated.

Car is a 2006 C4S

Thanks!

Edited May 29, 2011 by w00zie

[Mera]

I had something similar last year. My 2006 C2 was starting up at 3 and dropping to 1 once warm. Turned out one of the scavenge pumps was seized and then the banmk 1 timing chain broke and the engine needed a rebuild. Now the car starts up at 5 and drops to 3 once warm. Of course it might not be anything as serious for you, it might just be the gauge or pressure sender unit ...... eerily mine was at 52k miles when it happened

[cmills]

Suggest you have a borescore anaysis done.

[MichaelL]

This may not be a problem. At idle, fully warmed up, oil pressures around 1 bar are not uncommon. Your oil level may be a little low. The gauge should peg at 5 bars on cold start or close to it when warmed up and the rev's are up.

[logray]

I read a thread recently over on rennlist about an oil pump spring replacement solving this problem. A cheap and simple fix.

Of course the sending unit and it's wiring can contribute. Not as easy to replace, but not that expensive.

I've also read threads about partially seized, seized, or even incorrectly installed scavenge pumps causing oil pressure problems.

Oil viscosity and temperature can also play a role.

There is even the possibility of an oil passageway blockage somewhere.

On my 99' 996 the pressure would be 5 bar at startup but then sometimes at hot idle .8 bar. The pressure would also fluctuate a little at idle. Not good. Too low and it shouldn't fluctuate.

Cleaning the connectors on the sending unit did not help.

I decided to go "agro on it" and at not a huge expense while my engine was out for a valve job, I replaced:

Both oil scavange pumps (after tear down one of the pumps was not rotating as easily as the other one).

Oil pump hex driver with LN model, piston, spring, gaskets, orings, washers

Sending unit

Changed oil to 5w50

(also a complete valve job that discovered 5 bad guides, along with 24 new seals)

Now at a "warmish" stage 1 fans running at 210F idle, I'm at 1.2 bars without fluctuation. At startup 5 bars.