My car doesn't get used much this time of the year and I've noticed over the last few uses that the oil pressure doesn't quite reach the maximum figure it used to. On cold start it used to reach 90-95psi and fully warm 80-85psi at normal running speeds (2500-3000rpm) It now goes to a bit over 80psi on cold start and shows a bit below 80psi at fully warm running. Strangely the fully warm idle pressure is as before at around 40psi (mapped 900rpm idle)
I've checked with another gauge and it's the same. I'm going to change the filter to see if there's a pressure drop across the existing one (Bosch) There are no untoward noises from the engine.
Could it be a partially open pressure relief valve?
Comments would be welcome.
03 STi 51k

JohnD

 

When is the next oil change due ?
Oil could be thinning out due to fuel dilution causing a drop in viscosity and oil film strength.
Oil pump backing plate screws starting to come loose, bleeding off pressure.

The PRV in the oil pump is pretty reliable, don't tend to stick until after the crank bearings have failed and debris is circulated around the oil system.

Unlikely to be a fractured oil pick-up pipe drawing air on the EJ20 tbh.

Hope some of this helps.

Mick

 

It's due an oil change in March but has only done 2.5k in a year! the oil is Millers CFS 10/50 NT
I'm about to book a cambelt change. Would the pump be accessible during this?

JohnD

 

Well, I've changed the filter and hey presto! start from cold and the pressure went straight to just under 100psi! As it warmed to 80c the pressure was still 90psi at 2500rpm
So, it seems the problem was related to the filter. Visually, it looks fine but I certainly won't be using Bosch filters anymore! Incidently, the filter I replaced it with was a Blue Print which I've used before with no problems.

JohnD

 

All good then


Mick

 

just had a similar experience with a crossland oil filter. oil pressure was too slow to build from a stone cold start. swapped it out for a Halfords one and hey presto oil light goes out on the starter every time.
Upon inspection the crossland filter didn't have a bypass filter either. will stop being a cheap skate and stick to Halfords or o.e from now on.