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Reduced oil pressure warning only when engine hot??

rcnacura Apr 9, 2019

  1. rcnacura

    rcnacura US Spec 8V

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    So I've recently been getting reduced oil pressure warning (brown plug near oil filter) on my newly-ish built 83mm piston engine with roughly 7k miles. Really started happening after I changed from 0w40 to now 10w40. This ideally should not make a difference. Also happens when the car is at operating temp (over 180°F+ only).

    Was reading on previous gen ea888 engines the pcv could cause this and was a recall. Currently have CTS on the car so going to put stock back on just in case.

    I've also changed the actual brown pressure sensor too, oil is at normal levels. Is there anything else anyone would suggest before I try and tear down the engine for the worst case scenario of maybe rod bearings? Only thing is machine shop spec'd all bearings... Just at a loss of what to look for next - been riddled with issues, mainly all software related.

    Is there basic settings that needed to be performed after new engine installed as I'm not sure the shop did it since I have a strong angle sensor issues when I picked it up originally.

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  3. Gazwould

    Gazwould Registered User

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    The 0W40 will be thinner when hot than the 10W40 !!
     
  4. rcnacura

    rcnacura US Spec 8V

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    Only at cold temps as the first is cold followed by hot temp viscosity. Since this happens only at operating temps, why I'm not sure the oil would make the difference since I had 0w10 prior.

    Many have run 5w50 and 10w40 with no issue.

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  5. Gazwould

    Gazwould Registered User

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    :wink:

    What actual 0W40 and 10W40 did you use ?

    We could also talking semi and synthetic .
     
  6. rcnacura

    rcnacura US Spec 8V

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    Always full synthetic. Mobil 1 with 0w40 and motul 10w40 in now.

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  7. Gazwould

    Gazwould Registered User

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    Top man .

    Motul....? 10W40 is the Mobil 1 ' New Life' ?
     
  8. Retroman

    Retroman Audi A3 2010 Sportback 2.0 TDI 170 (CBBB engine)

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    I can't see that switching between 10W-40 and 0W-40 would lower your oil pressure significantly on an engine barely at 80C (180F). Normally this sort of "flickering" at idle is due either to a faulty "oil pressure sensor" or worn engine/oil pump. If it was me, I would get some tests done before doing anything drastic e.g. oil pressure via a separate measuring instrument, compression test and leak down test.
     
  9. rcnacura

    rcnacura US Spec 8V

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    I will install an external aftermarket oil gauge this weekend. I also bought a new oil pressure sensor, however, was reading others changed without much permanent luck. I also had nearly perfect compression and almost zero for compression and leak down test done about 2 weeks ago.
     
  10. Retroman

    Retroman Audi A3 2010 Sportback 2.0 TDI 170 (CBBB engine)

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    What's oil consumption like? Is it high? eg 1 litre every 1000 miles or even more than that? The 2.0 petrol VAG engines which had the "known problem" with heat damage to pistons and rings, usually start showing high engine oil consumption. Bad valve stem seals will also result in a lot of oil usage but not necessarily be so obvious on a compression test. If you're not using any significant engine oil, it might point to the oil pump or a common problem on certain VAG engines i.e. a blocked/restricted oil pick up pipe - work done on the engine may have dislodged debris/sludge and exacerbated this?
     
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  11. rcnacura

    rcnacura US Spec 8V

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    The engine doesn't have any significant oil loss, I've done oil changes every 3k miles or so because of adding larger baffled oil pan and cooler.

    All items on the car are new, valve seals, pistons, rings, rods, bearings, however, I reused the sensors, but even changing those didn't make a difference.

    Another friend with a built 83mm piston engine is also experiencing the same issue. We both are trying to figure out what it could be.

    I'll be buying some plastigage to see if the rod bearings could be out of spec.

    When I bought the main bearings, manual said blue, however, only Violet is available for this engine. Blue seemed to be for a4 engine. In the back of my mind I feel it's because if this, but still the bearings are in spec when it was assembled.

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  13. rcnacura

    rcnacura US Spec 8V

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    Interesting observation is that the error comes up only if the temp is 155-195F°. Anything above, it doesn't go off...

    I wonder if this is a software issue since the car usually operates around 200F°+.

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  14. AlS3BE

    AlS3BE Registered User

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    Could it be your larger oil pan/sump?
    The oil pick ups might not be reaching the oil at the bottom so when you corner or do anything other than standing still it goes off.
     
  15. rcnacura

    rcnacura US Spec 8V

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    I don't think this would cause it as the oil is increased so there should always be a plentiful supply and at the proper level.

    I'm going to try and take the pan of again to check the pickup tube.

    Still at a loss of what going on.

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  16. Retroman

    Retroman Audi A3 2010 Sportback 2.0 TDI 170 (CBBB engine)

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    With the problem worsening when changing from thinner (0w-40) to thicker (10W-40) it hints to me a slight oil restriction issue (e.g. the pick up as I mentioned above). Some of the classic BMW port injection engines M44, M52, M54 (1995-2005) although bullet-proof, could be a bit sensitive to thicker oil causing problems with the hydraulic valve lifters. I have personal experience of engines which had terrible cold start issues (particularly as weather got colder) which was completely eliminated when switching to a 0W-40 oil. Best of luck - we're all guessing on an internet forum :smile new:
     
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