• This topic has 63 replies, 17 voices, and was last updated 9 years ago by TedC.
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  • Any car mechanics?
  • dantsw13
    Full Member

    My Audi A3 3.2V6 quattro dumped its oil into the coolant system last week. Diagnosed as the oil cooler pump, not the HG, thank god.

    My local garage replaced the pump and gaskets, flushed the cooling system, filled the oil, and I picked it up yesterday. Now, the coolant warning light is on, but the engine temp and coolant level is normal. They have said it is most likely a contaminated sensor, and bring it back next week, they will reflush the cooling system, and fit a new sensor.

    I had a quick check today, and the coolant level is fine, but it is VERY oily. There is also a chemical smell coming from the A/C.

    Am I ok to drive it to work tomorrow?

    molgrips
    Free Member

    Airlock in the coolant perhaps? What does the manual say about the coolant warning – does that mean level is low or it’s too hot?

    I suppose there’s bound to be some oil left in the system – you could try flushing it yourself.

    gears_suck
    Free Member

    Absolutely not.

    sbob
    Free Member

    I suppose there’s bound to be some oil left in the system

    And it will float on the top…

    dantsw13
    Full Member

    Coolant light means low coolant or high temp. The coolant is not low, and on the drive home the temp rose to 90 (normal) and stayed there.

    dantsw13
    Full Member

    Gears Suck – what do you base that on?

    spooky_b329
    Full Member

    The temp could be inaccurate if the coolant is not circulating properly. Some cars have two temp senders, one controlling the gauge and another that does the light. I think.

    dantsw13
    Full Member

    The fact the gauge starts cold, warms up to mid range, and stays there suggests it is working. Coolant light comes on 15 secs after engine start from cold.

    markyboy
    Free Member

    If the temp gauge is working ok it is probably the level sensor that is faulty due to oil contamination.sensor should be in the coolant header.try disconnecting see if light stays on or goes off.if coolant level is ok sure it will be ok.

    dantsw13
    Full Member

    Thanks markyboy – thats pretty much where I’m at. I was just a bit surprised by the amount of oil still in the coolant. Maybe, as sbob says above, the oil floats to the top.

    ps – if anybody is actually a pro-mechanic, could you say so!!!

    parkesie
    Free Member

    Oils a shit to get out of a coolant system and will mess with float switches bear in mind even a little bit of oil looks like loads on top of water. I take it they put new oil in the engine so it should be easier to see if it old or new oil in the coolant if its alot of oil in the header tank.

    Ps actually a mechanic.

    dantsw13
    Full Member

    Yes, fresh engine oil, and the coolant is dark – guessing thats old oil. Would you be happy driving on the recommendation of the garage?

    Ive had recommendations to use a dishwasher tab in the coolant system to get out the oil – mad idea, or worth it?

    parkesie
    Free Member

    Without seeing it myself hard to say but if it is old oil in the coolant should be no problem. Not heard of putting a dish washer tab in to flush a coolant system but it could work. Would have to flush that out thoroughly aswell as no idea how it would behave with the different metals and seals in the system.
    Easier to flush system a few times, let oil float to the top and use a sucker refill and repeat till its all gone.

    dantsw13
    Full Member

    Thanks. When i checked the coolant level today, I think I was just shocked to still see so much oil in it, but from the replies on here, and a bit of googling, it doesn’t seem unusual.

    markyboy
    Free Member

    All you can do is keep flushing it.oil is a nightmare to get out of coolant system.radiator will also be contaminated and will take a while to clear .may need replaced.heater matrix also sounds contaminated if your getting a smell from heating…ps pro mechanic(there said so!!!)

    dantsw13
    Full Member

    Thanks – will be driving it tomorrow with a/c turned off. I’ll report back if I survive!!

    hora
    Free Member

    Im no expert (at all) but I wouldnt keep driving it in the meantime. Keep searching for answers and try Pistonheads as well or VAG forums?

    Nice car btw 😀

    I’m not sure exactly how a coolant level sensor works, but it’s something to do with the different electrical conductivity of air and water, so by knowing where on the probe that conductivity changes, it knows the water level.
    Having a coating of oil on the probe spoils the reading.

    We’ve had head gasket and oil cooler failures on buses and it can take weeks of flushing with dishwasher tablets to get rid of all the oil.
    But then that’s with 30m+ of heater hoses. 😉

    As long as you have manually checked the level, it’s safe to ignore the warning light.

    As for the air con smell, I don’t see how that could be related.

    craighill
    Free Member

    obviously make sure the sensor is actually plugged in, as this will trigger the light, it will most probably be on the underside. and make sure they used the proper coolant, it needs to be g12/g12+/g13 coolant from vw/audi, it should be bright pink, as aid above, it measures the resistance across the coolant, the wrong stuff can trigger the light.

    not a pro mechanic, but like I build my own bikes, I build my own cars, and have my own modded s4 b5 😀

    dantsw13
    Full Member

    Many thanks everybody! Well, the car was fine on my hour commute this morning – levels and temp fine. I had to turn off the ac and open the windows though due to the smell. Definitely smells like a mix of oil/coolant – not sure whether it’s just spillage from the job, or internal contamination of the heater matrix as above. Is Heater Matrix change a big job
    ?

    spence
    Free Member

    Is Heater Matrix change a big job
    ?

    In general the single most awkward job possible – there are obviously exceptions, MK2 Golfs? – most manufacturers start with the heater matrix and build the car around it.

    molgrips
    Free Member

    As for the air con smell, I don’t see how that could be related.

    Maybe he has a pinhole leak in the matrix?

    Try radweld..?

    dantsw13
    Full Member

    Well, the sensor hadn’t been clipped back on properly, so the coolant light is sorted – just the oily smelling aircon now!

    TrekEX8
    Free Member

    Dan, as an aside, not sure how much of a ‘gauge’ the temp gauge is? I’ve a suspicion it’s got about three positions – cold, 90degs and warm.

    TrekEX8
    Free Member

    Incidentally, how many miles??

    dantsw13
    Full Member

    60k ish.

    dantsw13
    Full Member

    Why do you say that? It takes about 5 min to slowly get to 90, not seen it hotter.

    TrekEX8
    Free Member

    I don’t think you will see it hotter – unless there’s a fault.

    TrekEX8
    Free Member

    I’d just keep a careful eye on oil and coolant levels: if the heater matrix is blocked internally, surely it wouldn’t lead to an external smell?
    My money is on smells from residual oil/coolant spills…..but I’m not a pro.

    dantsw13
    Full Member

    Ok – if that’s how it’s designed then no issue I guess?

    TrekEX8
    Free Member

    If you google, I think there’s a way of displaying various parameters, including coolant temp on air conditioning panel?? Seem to remember doing this on my A3.

    molgrips
    Free Member

    I’ve a suspicion it’s got about three positions – cold, 90degs and warm

    That’s cos cars have a thermostat to send cool and back into the engine when cold instead of through the radiator. So the hotter the engine gets the more coolant goes through the rad to keep it pegged at 90. The rad is designed to shift a lot of heat, so you only see the gague go up of the stat is fully open and the fans and the rad aren’t enough to cool the engine. It has to be pretty damn hot for this to happen nowadays with modern cars, hotter than we get here in the uk.

    TrekEX8
    Free Member

    Molgrips, I understand that, but I still don’t think it’;s a gauge in the traditional sense.

    molgrips
    Free Member

    I don’t see why not? What other sense of ‘gague’ is there?

    dantsw13
    Full Member

    I love a good stw tangential argument!!

    TrekEX8
    Free Member

    As far as I’m aware, the ‘gauge’ will read 90 if the temp is within prescribed limits – but it’s not a direct readout of water temp. But I may be wrong. As I say, you can display the actual water temp on the climate control panel.

    orangeboy
    Free Member

    Slight tangent. But was told the temp gauge on my td5 was not a proper reading
    It will slowly rise to the mid point and the moment the temp goes any hotter it will just push the gauge straight into the red at the top of the dial,

    Maybe utter tosh though

    molgrips
    Free Member

    I reckon it’d be harder to implement logic like that than just stick a normal meter in there.

    dantsw13
    Full Member

    Well, I seem to have flushed out all the oil, but I still have an oil smell from the heating. Will this go over time, or do I need to change the heater matrix?

    molgrips
    Free Member

    No thanks required.

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