Make a donation

Author Topic: [SOLVED] 19-20 PSI oil pressure on hot idle - too low?  (Read 1657 times)

Offline LC5F

  • Won't Shut up.
  • *****
  • Thank You
  • -Given: 15
  • -Receive: 50
  • Posts: 686
Re: 19-20 PSI oil pressure on hot idle - too low?
« Reply #30 on: October 27, 2021, 09:04:49 pm »
Their web site says nothing about flushing - https://products.liqui-moly.com/lm-48-installation-paste-3.html?___store=limo_b2b_com_en
I would say it should be fine just staying in the oil - it says use a brush to apply.

You will need another litre of oil too - 4.25 litres is a normal oil change amount, but even with the sump drained there is 0.25 litres still sat there - as you have had the sump off you probably will need need 4.5 litres

Hope this work sort your pressure out.

Offline OllieVRS

  • Taking part
  • ***
  • Thank You
  • -Given: 3
  • -Receive: 0
  • Posts: 32
Re: 19-20 PSI oil pressure on hot idle - too low?
« Reply #31 on: October 27, 2021, 11:07:03 pm »
Thanks for the reply LC5F. I'm going to send Liqui Moly an email and also do some further research on whether or not an oil flush and filter change is necessary.

As for the oil, I have a spare 1 litre bottle of cheap Millers' 5W-40 that I'll use if it's is too low.

Now, I wanted to add another topic to this post about the oil pump balance shaft timing:
As I've removed the balance shaft sprocket when taking off the pump (I should've taken off the pump sprocket instead) I no longer have the timing mark lined up accurately for the balance shafts. I know it can cause terrible vibrations if not timed correctly, and I want to get it right on the first go.

As everyone else online seems to have taken off the pump sprocket (not balance shaft sprocket), not many people have the same issue as me. I did find one Youtube comment though:



Basically says, that the balance shafts should be facing straight down or 'BDC' while piston 1 is at TDC. This same idea is reaffirmed by this scientific video about how balance shafts work:



Also on a side note, the big end bearings I ordered which are being shipped by FedEx have magically been stuck the Netherlands since Saturday, which is a bit annoying, so I can't guarantee I'll be working on the engine this week.

Offline OllieVRS

  • Taking part
  • ***
  • Thank You
  • -Given: 3
  • -Receive: 0
  • Posts: 32
Re: 19-20 PSI oil pressure on hot idle - too low?
« Reply #32 on: October 28, 2021, 01:35:22 pm »
Just received an email from Liqui Moly's support  :smiley::

Quote
Re: Correct Usage of Liqui Moly LM48 Installation Paste
Inbox

Steffen Niemietz <steffen.niemietz@liqui-moly.de>
1:30 PM (4 minutes ago)
to me

Oliver, thank you very much for contacting us and your interest in our LIQUI MOLY products.

No worries, when applying our LM 48 Installation past with the necssary amount, there will be no harm inside the engine / the engine oil and there will be no need for an immediate oil and oil filter change.



We hope we could help you with our information. Should you have further questions regarding our products we would be very pleased to get contacted from you again.

Freundliche Grüße / Best regards
 
i. A. Steffen Niemietz
Anwendungstechniker
application engineer

Offline Pudding

  • Global Moderator
  • Just look at my post count
  • *
  • Thank You
  • -Given: 2
  • -Receive: 578
  • Posts: 6713
Re: 19-20 PSI oil pressure on hot idle - too low?
« Reply #33 on: October 28, 2021, 01:44:20 pm »
Assembly lube is made to blend into engine oil, so no need for a flush.  Hell you could even use axle grease or vaseline and it would still meld into the oil no probs  :happy2:  It's only stuff containing, shall we say, 'particles' that a flush would be wise.

'Wrecked Revival' is spot on  :happy2:  Most people taking the sprocket off are fitting free wheeling sprockets and don't care about the balance weights being aligned.


2007 ED30 | 2009 TDI 140

Offline OllieVRS

  • Taking part
  • ***
  • Thank You
  • -Given: 3
  • -Receive: 0
  • Posts: 32
Re: 19-20 PSI oil pressure on hot idle - too low?
« Reply #34 on: October 30, 2021, 02:14:59 am »
Was just doing some research in preparation for the job, and came across a guide from ECS Tuning showing how to replace the clutch. The reason I was looking at this guide in the first place is because the flywheel uses the same bolt the balance shaft sprocket does.

Pudding mentioned earlier that the torque for this bolt is 20nm + 90 degrees, but I think he mistakenly found the torque for the pump sprocket bolt instead, which is a narrower M8x22 bolt (unlike the M10x22.3 bolt I'm going to be installing).

Here is an extract from the ECS Tuning guide showing the same M10 bolt being torqued to 60NM + 90 degrees  :surprised:



I know the bolt wouldn't snap if torqued down that much, but I'd be afraid of stripping the threads in the oil pump. I can't find a manual that states what it should be torqued to.

On Youtube people use red loctite on the bolt when installing a balance shaft delete freewheel, and one said that it's hard to torque down because it keep spinning, even with a screwdriver stuck in one of the holes on the pump to stop the balance shafts from spinning. So maybe I just aim for above 20nm + 90 degrees but not much more?

I'm just paranoid I'm going to get something wrong in this repair job that will lead to catastrophic consequences for my wallet and engine :smiley:

Offline Pudding

  • Global Moderator
  • Just look at my post count
  • *
  • Thank You
  • -Given: 2
  • -Receive: 578
  • Posts: 6713
Re: 19-20 PSI oil pressure on hot idle - too low?
« Reply #35 on: October 30, 2021, 10:10:18 am »
You're absolutely right, I did mistake that bolt for the oil pump sprocket, my bad!

As you can see in the diagram below, there is no reference to the balance shaft sprocket bolt. Probably because that bolt is not available separately and therefore not relevant to a repair manual, as you'd have to buy the whole £1500 assembly to get a new bolt! Crazy! The sprocket isn't available either.  VW really don't want people messing with it do they!

I don't think 60nm + 90 (that's a bit over 100nm total in reality) is achievable DIY.  The factory must have some special rig to torque that bolt up, hence why the sprocket and bolt are non serviceable parts.

As you say, all you can do is use high strength loctite, tighten it as much as you can, and hope for the best!

https://workshop-manuals.com/volkswagen/golf-mk5/power_unit/4-cylinder_injection_engine_(2.0_l_engine_turbocharger)/engine_lubrication/parts_of_lubrication_system/assembly_overview_parts_of_lubrication_system/part_2/
« Last Edit: October 30, 2021, 10:12:10 am by Pudding »


2007 ED30 | 2009 TDI 140

Offline OllieVRS

  • Taking part
  • ***
  • Thank You
  • -Given: 3
  • -Receive: 0
  • Posts: 32
Re: 19-20 PSI oil pressure on hot idle - too low?
« Reply #36 on: October 30, 2021, 05:28:31 pm »
Quick update, the WASA freewheel bolt is 50NM, so I'll be aiming for that now.



Offline OllieVRS

  • Taking part
  • ***
  • Thank You
  • -Given: 3
  • -Receive: 0
  • Posts: 32
Re: 19-20 PSI oil pressure on hot idle - too low?
« Reply #37 on: November 03, 2021, 07:05:20 pm »
Alright, after working in 5 degree weather I've replaced the connecting rod bearings with the help of a friend. Here are pictures of two of the top half bearings, quite pitted as you can see (crankshaft looked fine):





All was going well (bar my low range torque wrench not clicking anymore) until we got to putting the balance shaft sprocket back on with the pump already installed.

The bolt was quite resistant but I thought nothing of it, as I had the idea of '50 NM' in my head and it definitely wasn't going in crooked. Just under half way in, and struggling for torque I removed it to see what was going on, and this is what I found. Left bolt is new one, right is original one that I took out:



Thankfully, the balance shaft threads seem fine, they must be much stronger than the bolt material as the seem to have carved into the bolt threads.

So it turns out I'm a bit of a idiot when it comes to making sure which bolt came from where.

While writing this post, I double checked on google images for reference to what the bolt should look like. Notice how they have washers and how the thread is much further apart than on the bolt I tried inserting.



This also means I have screwed the correct spline bolt into the the wrong place on the oil pump, marked as 'WT' on the bottom right of oil pump diagram I posted earlier. :doh: Probably completely stripped the thread on that, thankfully it only holds the plastic thing to the sump so I don't think it's too vital, I could be wrong though.

Now I need to see if I can get a replacement for the bolt with the washer or just stick the old bolt in and hope for the best.

EDIT: Have now ordered some 'JB Weld JB27136 Perma-Lock High Strength Thread Locker' from Amazon as after a few hours of searching, it turns out it is impossible to buy that bolt.
« Last Edit: November 03, 2021, 08:52:22 pm by OllieVRS »

Offline Pudding

  • Global Moderator
  • Just look at my post count
  • *
  • Thank You
  • -Given: 2
  • -Receive: 578
  • Posts: 6713
Re: 19-20 PSI oil pressure on hot idle - too low?
« Reply #38 on: November 04, 2021, 01:34:32 pm »
Apart from the pitting, the old bearing shells look fine.  Not sure what the pitting is all about.  Acidic corrosion from lots of short journeys?

Yes indeed, one cannot buy that bolt.  I would just reuse the old one, but just give it a set torque figure as high as you dare. Obviously you can't do the 90 degree bit again as the bolt has 'stretched' once already.

Getting there!


2007 ED30 | 2009 TDI 140

Offline OllieVRS

  • Taking part
  • ***
  • Thank You
  • -Given: 3
  • -Receive: 0
  • Posts: 32
Re: 19-20 PSI oil pressure on hot idle - too low?
« Reply #39 on: November 14, 2021, 01:04:52 am »
I'm going to cut straight to the chase before I say anything else: THE ENGINE IS NOW FIXED!

I was going to post earlier but I had to make sure it was fine by doing some endurance and stress tests, and after roughly 60 kilometres (37 miles) of driving I am fairly certain it's fixed.  :grin:

I'll just mention a few things about the reassembly job before I go into detail about what caused the low oil pressure and costs/time etc.

I got away very lightly with screwing in the wrong bolts in earlier - The correct bolt (which I screwed into the hole marked WT) was barely even scratched from being inserted into the wrong thread. The thread it was screwed into looked slightly mangled, but nothing a little threadlocker couldn't solve. If anyone is using this post as a guide, always remove the pump mechanism sprocket, not the balance shaft sprocket, and make sure you put the in pump chain tensioner and sprocket simultaneously, as otherwise they won't fit.

Once the bottom of the engine was assembled back together and filled with oil, I cranked it without the coil packs plugged and the HPFP fuse out, to circulate the oil around. Then came the nervous part of actually running it. It ran rough for about 3 seconds, then became smooth. All perfectly normal behaviour.

After about 15 minutes of running at idle, an oil drip developed from the pressure switch area. After a further 10 minutes it started trickling, so I shut the engine off. The pressure gauge showed 20 psi with the oil not fully warmed up, so the bearing change didn't affect the oil pressure, which is what I expected. I will go into detail later about the correct specs for oil pressure.

I've circled a free-spinning part of the gauge where the leak most likely came from. It lost about half a litre of oil through this connection.



Upon putting the new pressure switch back in, no more oil leak, confirming the gauge was at fault (although there is a minute oil leak from the vacuum pump).

After letting the car warm up I did some harsh test driving, and I would hold the RPMs at 1200-1500 after giving it the beans to gauge if the pressure is good. If the pressure was bad, it would toggle at these RPMs. I then did an endurance test of 30km on the motorway to see how it would hold up on a longer journey. Neither of these tests made any lights pop up, and the engine sounded perfectly smooth.

Now the car has failed the NCT (Ireland's version of the MOT) on the two front rearmost wishbone/control arm bushings and the rear discs, as the pads are not fully touching the disc due to a lip on the disc. Not a bad verdict as it could failed on so many other things, considering it's dodgy history. I'm having my mechanic friend (same one that was with me when I bought the car) change out the previously mentioned items, and the NCT is now booked for this coming Wednesday.


THE VERDICT:

Unofficial oil specs from an Audizine forum post are as follows:

Idle 1-1.2 bar or (14.5-17.4 PSI )
2000 RPM 2.7-4.5 bar (39-65 PSI)
3000 RPM 3.5-4.5 Bar (51-65 PSI)


My car achieved (on 5W40):
Cold Idle: 55 PSI
Hot Idle (After harsh driving): 16.6 PSI

I don't remember the measurements for the PSI at higher RPMs, as it was the idle oil pressure I was concerned about.

If your pressure is lower 17.4 - 23.2 PSI @ 1200RPM/1500RPM for over 0.5 seconds you will get a low oil pressure light that will disappear if the pressure improves. If it remains in this condition for over 1.5 seconds then the oil pressure light will stay on no matter what RPMs you are at (I have conflicting info about which RPM the ECU polls the pressure switch at).

The oil pressure switch is not polled by the ECU at idle.


What caused the low oil pressure for me?


To be honest, I'm not 100% sure, but I think one of these or a combination of these was the culprit:

Faulty PCV: With the Oil Filler Cap off the RPMs didn't drop, indicating it was faulty. AFAIK, this causes too much crankcase pressure, putting strain on the pump, reducing oil flow or something like that.
Over-filled Oil: The oil in the car was overfilled when I bought it, which strangely enough can cause low oil pressure.
Blocked Pick-up Pipe: The pipe itself wasn't too blocked, there was some dirt/sludge around the edges. I found some broken off plastic pieces in the sump that had broken off the oil pump chain guard, likely from when the balance shaft sprocket bolt sheared in the past. These could've floated into the pick-up temporarily blocking it.

The oil filter was also old and filthy, but nothing that would stop oil flow.
Changing out the connecting rod bearings didn't affect the oil pressure, so it definitely wasn't those either.
I inspected the oil pump when I took it out and it was perfect, bar the scars from the balance shaft sprocket coming loose in the past.


So how much did all of this work cost?


€1,115. This cost includes 2 torque wrenches, about 20L of different quality engine oil, at least €150 of just VW stretch bolts, engine components and expensive shipping fees from the Czech Republic.

All of the work was done by myself and the help of a friend, so none of this cost includes labour. If a mechanic were to do the same work I did, I assume the total cost would be €2500+.


And how long did it take?


Roughly 3 months, or about 100 hours of my spare time lying on the ground under the car. I could've had it fixed by the start of October had I known the oil pressure specs before diving into the guts of the engine.


That's all from me. I seriously owe you a pint @Pudding for your help in all this.  :drinking:
« Last Edit: November 14, 2021, 01:08:38 am by OllieVRS »

Offline Pudding

  • Global Moderator
  • Just look at my post count
  • *
  • Thank You
  • -Given: 2
  • -Receive: 578
  • Posts: 6713
Re: [SOLVED] 19-20 PSI oil pressure on hot idle - too low?
« Reply #40 on: November 20, 2021, 01:50:04 pm »
Blimey, what a journey that was!  Glad it's all sorted now  :happy2:


2007 ED30 | 2009 TDI 140