VZ Crewman 5.7 litre LS1 Oil Pressure Issues - wierd symptoms.

[MiKExAUS]

i recently purchased a vy clubsport with over 300k on it everything seemed fined until i changed the oil, oil pressure light came on when i was getting it of the ramps so every time after a cold start the oil pressure would take about 10 or so seconds to build up this was real you could here the motor sound change, i tried different oil problem got worse the thicker the oil but as the topic post parking it on a nose down incline pressure came up straight away on start up. After plenty of reading and talking to people who rebuild these, it all seemed to point to the dreaded oil pick up tube o ring , i was quoted 1,5to 2k for oil pump replacement removing the motor or dropping sub frame i will be doing a rebuilt on the motor but wanted to hold off till i have a few more funds so spending 2k seemed to be a waste , i decided to replace it myself this is a 100% doable on the car but is not ideal as there is not much room to work and oil sump leaks are a real possibility , OK new oil pump in and the pressure problems solved motor is surprisingly quite for its age the only thing i would do different if attempting this would be to install a extra clamp on the pick up tube they are on ebay for around $20
i came across this post with out a solution i hoped this helps somebody

Hi, did you replace the oil pump for extra precaution? It sounds like the pickup tube O ring was causing the issue so wondering why you also replaced the pump.



I have the startup rattle and trying to get away with only replacing the O ring!



Cheers

 

[carcollector]

In the end, I don't think it was the O ring. I think it was wear and tear on the relief valve piston, from many KM of opening and closing, wearing the piston out of round, and also scuffing the end so that it didn't seal properly. That's the only explanation I can come up with.

I ran out of time and patience to have a look at it myself, so I bought a brand new oil pump and gave it to a mechanic to fix. He first tried just replacing the O ring, but the problem remained. Then he replaced the whole oil pump, and problem disappeared. I got the old oil pump back, and it was in surprisingly good condition except for the relief valve piston, which was quite worn and scratched on the end like it had been dragged along concrete or something similar. No problems with oil pressure since then.