Help - No Oil Pressure on start up

[Oz928]

Help,

I'm getting zero oil pressure on start-up - after about 10 seconds it comes up fine ? Every thing I've been able to find on this suggests the OPRV sticking open.

So, removing it to check it out and see what I can find - cap off spring out (looks fine), but how do I remove the piston from the bore ?

Any help much appreciated:-)

Cheers

Al

[XLR8928]

Any weird or disconcerting noises at startup?Have you considered that your Oil pressure transducer (sensor unit) may be malfunctioning? A mechanical gauge in parallel with it could verify.
Good luck,
-Kerry

[Mrmerlin]

helpful to include the year BUT
more than likely is the oil pickup tube seal inside the pan has failed,
thus it takes a while for the pump to suck enough to supply ,
remove the pan and replace this seal first

[JK McDonald]

Hey Oz - Could you give us a little background on how the problem began ? Have you had the car very long ? What is the year ? Has this been an on going issue over time or just a recent development ? Did you change your oil (brand/viscosity) and the oil filter (correct type) just before the problem began ? Have you eliminated a defective oil pressure sending unit by connecting up a mechanical pressure gauge ?

The older style (piston cup/spring) oil pressure relief valve can stick open slightly from hardened varnish or particles of crud in it's bore. Normally the piston does follow the spring out during dis-assembly but if it is stuck inside the oil passage there is an expanding tool that you might use to fish it out. On one 80 model 928 it took a combination of multiple doses of carburetor cleaner and much perseverance as well. In a pinch I've heard of some using a wooden dowel pin that was trimmed down to just fit inside the piston and gently twisting it out.

Here is a brief overview of the 928 oiling circuit -
http://www.justanswer.com/porsche/5vdcg-porsche-928-no-oil-pressure-1978-928-removed.html

Good Luck and keep us posted, Michael