7 replies to this topic

[kavesh]

Hi all

 

My 308 motor was rebuilt about 2000kms ago. Not really an issue but I am always nervous about the oil pressure when warm at idle, always dropped to less than 1 bar or 14psi. give it a rev and the pressure climbs up 3 bars or 43 psi always.

 

After my recent oil change, using 15w40 oil (oil is same as before), I decided to open up the oil pump, the gears are all in good condition. I decided to give the 2 halves a little wet paper to even out any uneven surfaces and bring the halves closer together without binding. (I am reusing the oil pump, its not new, probably original).

I also decided to add a little shim by the relief spring maybe 2 to 3mm.

 

Anyways now on cold idle I am getting 4 bars or 58psi oil pressure and when warm at idle it reading 2 bars or 29psi.

 

When cruising the oil pressure reads maybe 5 bars or 72psi, probably closer to 6 bars or 87 psi

 

Is this too much pressure? Should I consider removing the shim from the relief spring?

 

Or am I overt thinking things.

 

Appreciate the advice, thanks

[warrenm]

It's not too much pressure, Holden V8's are notorious for low pressure at idle. 

[axistr]

The rule of thumb used to be 10psi plus 10psi for every thousand RPM. High oil pressure costs HP and increases fuel consumption. You don't need big number pressures. I would remove the shims under the relief valve before you start blowing out gaskets or oil filters. I sometimes fitted a 0.5mm shim under the relief valve but 3mm would be way too much unless the spring is bugged.  

[greenhj]

Probably too much.

 

Thinner shim required.

 

No need for more than 60psi and 20psi at idle wouldn't bother me at all.

[gtrboyy]

Yeah too much you want 10psi every 1000rpm.

15psi hot is decent for holden red...flow of oil more important than higher pressures lots of little tricks you can do but they'll still read on low side

[kavesh]

Thank you kindly for all responses. I shall remove the shim and see what the readings look like and may then use a thinner shim if need be.

[Rockoz]

Ive had a few Holden V8s over the years.

Oil pressure at idle when warm was always what you would consider low.

Talked to a couple of performance engine blokes and they said it was normal.

An added bonus though was when the oil light started to flicker at idle when warm, you knew it was time for an oil change.

 

Cheers

 

Rob

[EunUCh]

According to workshop manuals (both 6 & 8 cylinder) it was normal for the oil light to flicker when engine was warm , from memory it was something like 10psi or less for this to happen which seems a little on the low side considering we have a 1933 car at work and the oil pressure when cold is 50psi and no mods have been done to oil pump , it drops a bit when warm but not by almost half.

One thing the workshop manuals say is that the pump gears should be proud of the pump body by 2 thou and then the gasket will take that up and add a bit for clearance , again its only a couple thou needed for end float clearance.