All Things Mk5 > Mk5 General Area
[SOLVED] Low oil pressure at idle
OllieVRS:
Took the oil pump out, and the pump mechanism to inspect it, as suggested by the WASAmotors engineer I've been emailing. This was in order to check the oil pressure release valve was not stuck open (mine isn't) or there isn't any wear in its bore. It's the brown thing with the ridges.
I tried to get the back of it off to further check, but even with a breaker bar I couldn't.
I sent to first picture to the WASA engineer and he had this to say:
Bashing in my M8 spline with a mallet and using a wobble 1/4" extension I managed to get all three oil squirters/oil jets out, and I took a short video of the condition of their ball-spring valves.
eature=share
As you can see, the first one has very little resistance to pressing it and even gets stuck when pressed down. The second has medium resistance and the third a high resistance. The first one is the most likely cause of the low oil pressure at idle.
Now I know the WASA engineer said the pump is bad. But my oil pressure above idle is absolutely fine, same as it was 11k miles ago, and within VWs oil pressure specification. I've had 5k km oil filter changes with no metal shavings at this oil pressure. I can't justify another ~€300 for another if mine is working sufficiently.
My plan is to replace the three squirters and that's it. Not sure I'll bother with replacement bolts for the oil pump since there's no active balance shaft there anymore to shake them out anyway.
Cheers, hopefully this is helpful to someone :happy2:
pudding:
If those marks at the bottom of the pump housing are gouging, then I think Wasa Motor are right. It certainly doesn't look healthy.
Maybe pick one up from ebay, strip it down and see if it's better than yours?
OllieVRS:
Little interim update while waiting for the oil squirters.
--- Quote from: Pudding on May 12, 2023, 06:17:17 pm ---If those marks at the bottom of the pump housing are gouging, then I think Wasa Motor are right. It certainly doesn't look healthy.
Maybe pick one up from ebay, strip it down and see if it's better than yours?
--- End quote ---
Took a more serious look at the gouging, as I realised it may have looked pretty serious from the photo I sent.
Gouging as seen from my phone camera:
Gouging as seen from my endoscope camera. Enough to catch a nail, but not as deep as it looks from the previous picture:
PRV bore inspection, doesn't seem worn out. No wiggle room.
And the PRV spring is still intact.
I can't justify a >€300 used oil pump when the oil pump I have seems fine and the pressure it puts out is within spec. I read on the Audizine forum that the PRV is designed to open at 58 PSI anyway to prevent over pressurising, and my oil pump gets up to 58psi at 3k RPM.
We'll also see how the new oil squirters affect the pressure at higher RPMs, I doubt they will, but there's a chance. Here's to hoping. :drinking:
Idle pressure is the only one out of spec so that's definitely going to be fixed by this. Here are the three squirters next to each other, spot the odd one out:
Apologies for the photo-heavy post.
OllieVRS:
I was right. OllieVRS 1-0 WasaMotors Engineer.
Just joking, there was probably some truth to his claim, I'll go into detail later.
So I've fixed the idle oil pressure. After replacing all three accessible oil squirters, the hot idle pressure has been raised from 0.8 bar to 1.2 bar (12psi to 17psi).
The original guidelines from the Audizine forum state that the measurements are at 80 degrees engine oil but I think that's a load of BS so I just let the car idle for 15 more minutes after the coolant hits 90 and then take my measurements.
Measurements before fix:
Idle: 0.8 bar (12psi)
2000: 3.6 bar (52psi)
3000: 3.9 bar (57psi)
Measurements after fix:
Idle: 1.2 bar (17psi)
2000: 3.6 bar (52psi)
3000: 3.9 bar (57psi)
So only the idle pressure has changed after the fix, the other pressure remain identical. Measurements done on 0W40 before and 5W40 after, so difference should be negligible.
Final Hot Idle
Video of Idle-2000-3000rpm
eature=share
Picture of original oil squirter (left) 06F 103 154 A, next to newer revision oil squirter 06F 103 154 C. The only visible difference is that the ball-spring on the newer one has a flat face. Apparently VIN numbers matter when buying these, I asked the guys at Skoda-Parts.com and they confirmed the newer one was the one for my Octavia.
Picture of where the oil squirters are located and how we reached them (the crankshaft has to been turned to a very specific angle for each of the three). We used 1/4" wobble-end extensions and big hex M8 spline bits inside 10mm sockets, and torqued the new ones to 27Nm. A long screwdriver is also required to point the spray jet nozzle in the right direction as you tighten the bolt and to line it up with the flat groove in the block.
My final thoughts are that my pressures are well within spec, but seemed to be capped just under 4 bar (59psi). I think this is due to the spring in the pressure release valve in the oil pump being weaker due to age and poor servicing in the past, so it's opening slightly prematurely. Just 10k miles caused my idle pressure to drop from 18psi to 12psi, basically one of the oil squirters collapsed in that mileage, so I would be anxious that the spring in the PRV could collapse in similar mileage too.
The WasaMotors Engineer pointed out the scratches in the pump mechanism look bad but it's impossible to measure the effect of them on the oil pressure. And that my pump would benefit from their oil pressure fix. Which I would look into were it not for the fact that my pump's PRV bolt seems to be permanently glued shut. Not even a breaker bar could get it open :thinking: . It must have been already fixed once by a previous owner, and they bodged it.
The scratches would affect the pressure across the board, whereas the PRV would only affect the higher RPM pressure. My 3000RPM pressure only being slightly higher than my 2000RPM pressure would suggest the PRV spring is the main limiting factor.
Ideally I should be able to surpass 4 bar at 3000RPM. I'll remeasure it in a few months to see if the upper pressure limit has degraded any further.
That's all for now. I'm going to work on an oil pressure solution guide for the forum considering how much knowledge I've gained researching this topic, and also from experience. Hopefully that will be of use to a few people :happy2:
Cheers
pudding:
Yeah the gouging marks look far less severe in the newer close up pics :happy2: Still not ideal, but not as bad as I first thought.
Hmmmm, yeah, definitely evidence of poor maintenance in the past. The very dark staining on the metal castings is a clear indicator of skipped oil changes.
Still, you've persevered and improved the low rpm oil pressure, so go you fella :happy2:
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