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Yellow sludge in oil

Crazypete00 Oct 30, 2012

  1. Crazypete00

    Crazypete00 Active Member Audi S3 Audi A4

    Checked my oil earlier it was a tad low but also noticed a small amount of yellowish sludge on the dipstick and a small blob under the cap. I know when this happens it usually means head gasket! But was wondering because I fitted a catch can about 2 months ago and did the n249 bypass could it be just a bit of condensation?

    When I did the n249 bypass my puck valve and all the pipes where blocked with the same yellow sludge (like the pics on the how to thread) so could it be from that?

    I can't see any oil in my water and that level looks normal.

    i will be removing the sump on the weekend to do the oil pickup so I can further inspect it, just wondering if anyone has had similar issues or ideas?
  2. Carpy25

    Carpy25 Member

    can be due to lots of short runs when the car does not get up to temp first thing I would do is wipe off all I could then go for a long run and check again keep your eye on the temp gauge just in case and take some water with you

  3. The Doctor

    The Doctor Well-Known Member

    I agree with Carpy25 - can also be due to short runs in cold weather. Wipe it off and keep an eye on it for now, especially after a longer run.

    I'm also doing my sump & pick-up pipe at the weekend, weather-dependent... so will be thinking of you!
  4. Crazypete00

    Crazypete00 Active Member Audi S3 Audi A4

    thanks both, ye the car is my daily runner to work which is 9 miles so only does short runs.

    i forgot to say that when i removed my oil catch can there seemed to be a bit of water in it and yellowie sludge aswell. im wondering if some how this managed to run back down into the breathers...

    what im i looking out for in the temp gauge? usually dead on 90c sometimes a bit lower.

    ye not looking forward to doing the oil pickup, ive removed sumps before but this one looks a bit trickyer plus doing a full service on it.
  5. aragorn

    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

    Temp guage should never be "a bit lower", it should always stay exactly at 90 once its reached temp. If it moves, its probably a lazy thermostat letting the engine run cool. Use the climate control diagnostic reading to see what the coolant temp is actually doing (channel 49).

    The yellow stuff is what you get when you mix oil and water, usually it forms from the condensation inside the engine, hence short runs causing it. When the engine gets fully up to temperature the water evaporates off and the oil part returns to the sump so the stuff disappears.

    It takes about 5-10miles of driving before the oil temperature reaches its optimum level, if your work is 9 miles each way then i'd suggest thats probably enough that its not "short" journeys. If its 9 miles total then it probably is a bit on the short side.

    If your stat is lazy and its never properly getting to temperature then this is likely adding to the problem.
  6. Crazypete00

    Crazypete00 Active Member Audi S3 Audi A4

    well I did the oil pick up today. Did it in my garage with a trolley jack which was awkward but doable. Everyone one should check their pickup mine was mega blocked, I couldn't see the mesh! I had bought a new one but they sent me the short version so I ended up cleaning it with a compressor and card cleaner. Also did a oil change and all the filters. Now I just need to do the thermostat and change the coolant.

    For people looking to do the pick up I recommend the 5mm hex ball tool. Made life easier with the sump bolts. A good socket set and wobbly extensions also handy to have.​
  7. danger S3

    danger S3 Member

    Good work :beerchug: should help your engine last alot longer :thumbsup:
    I agree everyone should check there pickup, I've seen some nasty ones.
  8. vfr800

    vfr800 Active Member Team Dolphin Grey Audi S3 quattro Audi A6


    Good job, I really need to pull my finger out and get mine done.

    I'm sure by this you meant you used a trolley jack to put it on axle stands. Darwin *will* catch up with people who only use trolley jacks to support their vehicle while they work under them.

  9. Pops848

    Pops848 Active Member

    +1 for the oil pick up and sump clean, I did mine when I had my 8L and my oil was running "clean" for a long time! It took ages before it went fully black like it usually does straight after a change.

    The sludge is more then likely condensation build up, head gaskets are not a common problem for these engines. I had mine go, but that was because my CTS blew it self out of the housing and pissed coolant all over my engine bay straight down the air filter. Ruined my head gasket and MAF sensor. Ended up doing the head gasket, MAF, put stock air filter and housing back on and also cleaned the sump and oil pick up. Was running very well after all that!
  10. Crazypete00

    Crazypete00 Active Member Audi S3 Audi A4

    Ye sorry I did use axel stands (this is defo a must) my jack is knackered and slowly lowers itself.

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