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  1. #1
    vcondis
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    Cold weather oil cap condensation.

    As cold weather is returning,I am thinking of ways to reduce the reccurence of condensation,the milky looking stuff found underneath the oil filler cap. Every year this has occured as weather cools and goes away with the return of spring. I change oil before and after the cold weather but the condensation remains. "Drive more" those of you in warmer climates may say. Where I live,sometimes temps remain below freezing for weeks on end and my short 5 mile commute is barely enough to warm the car up,in fact I have gone on 100 mile drives that barely made a difference on the condensation,only warm weather cures it. I have been thinking of blocking one of the "kidney" grills thus reducing cold air flow to the engine compartment,this should increase underhood temps and is something that I see truckers do in the winter.Any thoughts or experiences on this?
    Thank you.


  2. #2
    Eurodavid
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    Re: Cold weather oil cap condensation.

    Blocking any air flow, whether freezing and/or not, you'd be the first I ever saw and/or heard do it on a BMW. Even on bimmers from Finland and Sweden, I've never seen this and/or heard this. Makes sense though (I too remember seeing it on trucks from my days of living in the upper Midwest). Still, allotting one time slot of 25-35 mins for one good hard drive every 3-4 days ought to keep your engine healthy and fine, don't ya think? JMHO.

    Eurodavid

  3. #3
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    Vcondis, I'd give it a try, however I would keep(m

    an eye on the temp gauge, if you have the high end cluster look at the engine temp there as it will give you the exact reading. If the temp never gets above freezing you could most likely block both of the kidney grills as there is still air that gets in from the lower bumper area. The cabin heater also helps extract heat from the engine, a useful tool for anyone if you notice that your engine starts to overheat.
    About a month ago I monitored my engine temp as I kept reducing my electric fan (that replaced the mechanical water pump fan) speed down. I had it almost off and didn't see any rise in the coolant temp as I drove the car.
    The outside air was in the 50's (F). I wouldn't try this in the summer, but with temps below freezing it shouldn't present a problem, just keep an eye on the temp gauge especially during periods when the car isn't moving. FYI, turning on the A/C will make the Aux fan come on if the engine needs some quick cooling. It will increase the heat load after a few minutes, but does help to quickly cool the radiator down if you are stuck in traffic.
    Vcondis, do some experimenting and report back.


  4. #4
    vcondis
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    Re: Cold weather oil cap condensation.

    Euro I do drive it around running errands and such on my days off but seems to make little/no difference,the problem is that here (Boise,Idaho) the traffic is very light and moves very efficiently with little stop and go driving and at typical wimpy American rates of acceleration and speed. This kind of driving does not excactly strain a car designed to be driven hard and so a person can drive across town and back on cold days and the lower rad hose is still barely lukewarm (temp gauge at 12 o'clock,thermostat is newish and works fine). So other than driving around town in 2nd gear (that kinda sounds fun) or starting and letting it idle for some time (owner's manual says not to) I just can't think of anything else.
    Thanks for your advice,actually I wondered what people in Sweden etc do,but maybe the more congested European cities' more stop and go traffic helps warm their engines up.

  5. #5
    vcondis
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    Re: Vcondis, I'd give it a try, however I would keep(m

    Thanks Jim. My car (97 528i 5spd 112k miles)has no high end cluster so I cannot see the exact temp reading,so even though the temp gauge is in the normal 12 o'clock position,on cold days the lower rad hose is just lukewarm. As you said even blocking the kidney grill/grills there will still be air coming in through the bumper openings,I should be able to tell if the engine is getting warmer by feeling the lower rad hose and by hopefully seeing a reduction in the condensation. I might just give it a try and let you guys know what happened.

  6. #6
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    Truckers do it because a diesel engine ...

    characteristically runs cooler than a gas engine.
    Ed in San Jose. BMW CCA member since 1987 (Nr. 62319). Golden Gate Chapter. '97 540i 6 speed. Build Date 3/97. Aspensilber over Aubergine leather.

  7. #7
    Craig in Canada
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    Re: Cold weather oil cap condensation.

    That area of the oil filler cap doesn't see any direct contact from the oil because of shields in place over the camshafts. This entire area is exposed to vapours only and often has gooey residue all over the place in all seasons, not just this white stuff. The cap and that area is always going to be the coolest part of the engine, cardboard or not, and will be the most prone to condensing vapours.

    You need to be more concerned about the water (and far worse - fuel) content in the oil which is actually lubricating the engine, not a little bit of unsightly buildup on the cap. You need to get the OIL up to temp, which takes a lot longer than the coolant, and isn't going to be affected as much by a little wind under the hood.

    My 528 used to be a long-tripper all year round when we lived in downtown Toronto, had no kids, walked to work, and used it for road trips only. Now it's a suburb taxi for mom to drive kids here and there and go shopping. I get some of the buildup you're speaking of, but there's still some highway trips in there to get the oil hot enough to flash everything off.

    One of the things you want to do is warm the engine up as fast as you can, and as thoroughly as you can. Make sure you don't idle it in the driveway trying to warm it up - it's pointless, pollutes the environment, increases wear, and gets lots of fuel and moisture into the oil which isn't good for anyone. Get underway and drive "easy" as things warm up. My car will be warmer from one minute of easy driving in my subdivision than 15 minutes of idling.

    Another thing I've done whenever short tripping as soon as winter actually hits is I manually override the HVAC fan speed to the startup default of 3 bars. You'll notice that on AUTO as soon as the coolant temp gets up a bit in the blue the fan comes on high speed trying to warm the cabin. This is all heat that could be in your coolant and oil instead of fruitlessly trying to heat the cabin for 5-10 minutes. I'm dressed in winter clothes already, I'm not uncomfortable, and I'm getting out in a few minutes anyways. Just make sure the windows stay clear. I found this lower fan speed does a good job of not robbing all of the heat from the engine but still being perfectly comfy inside. This means less time the engine is in "warmup" mode running rich and the entire system gets to a higher temperature before you have to shut down again.

    On longer trips I let automatic do its thing. Also by not blasting the windshield with lots of hot air, it may stay below freezing so a little dusting of snow while parked simply blows off instead of forming ice that needs scraping.

    Those who live where it doesn't actually get cold will probably think this is all goofy, but I've learned a thing or two over 9 Canadian winters with my E39. Of course once a week I read about Texans idling their cars for 20 minutes to warm them up because it got down to the 50s...brrrr


  8. #8
    Jim Cash
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    Re: Cold weather oil cap condensation.

    I saw some notation from BMW that states never to block the incoming air regardless of external temperatures.

    And, unless you are in extremely low arctic conditions, this actually makes sense since the system (thermostat) will keep the engine coolant at the proper temperature and will not send any to the rad if the coolant temp is too low.
    I think the BMW concern is that people forget to remove the blockage and cause overheat issue - but still they do test their cars in very cold climates and the system is designed to handle it.

    I do monitor my coolant temp in the cluster from time to time. In normal summer times it operates at the standard 108-109C and even on the coldest winter days (even in blinding snowstorms) it will still be operating at 107-108C (have never seen below 106 once the engine is warm - which normally takes up to 15 minutes in cold weather.)

    That is the temperature at which the coolant is coming out of the engine at the thermostat - it is also the temp that is going to the heater circuit.

    I think the 6 cyl runs a little cooler than this but the concept is the same.

    Your issue is mostly that you are making those repetitive short 5 minute trips and the engine is not getting hot enough to get rid of the condensation that does happen when there are still vapours in the system. They condense on all the external metal parts that are the coldest and your valve cover and cap are such.
    That type of operation is absolutely the harshest environment for an engine - and will also affect other components such as exhaust system.


    Several things to look at:

    - thermostat. You may be running cooler than you think. The temp gauge reads straight up as soon as the coolant temp reaches 70C so you will not know if your thermostat is opening too soon (or leaking).
    You actually can activate the temp reading in your cluster but it is more difficult to do so.

    - engine oil - make sure you are running a good synthetic as they are not affected as much by condensation.

    - it might be worth your while to have a compression test in case you have any excess blow by gasses that are causing excess moisture in your crankcase. Also tests of the crankcase vent etc.

    - an analysis of your oil will also check if you are getting any coolant leaks which can also cause this issue. Do you ever have to add any coolant (even small amounts)?

    Cheers
    Jim Cash

  9. #9
    Jim Cash
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    Interresting - I can't remove my oil filler cap

    Well actually I can remove my oil filler cap - but it is not a brilliant move while the engine is running.

    On my non vanos 8 cyl the cam chains run directly below that cap and on the one occasion that I did remove the cap I quickly observed that the system has the capability of sending a fine stream/spray of oil completely across to the opposite fender.

    So MY cap gets a nice warm oil bath all the time - sorry to hear your 6 cyl caps are neglectfully left out in the cold :-)

    Cheers
    Jim Cash

  10. #10
    Jim Cash
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    Coolant temp reading

    To read the actual coolant temp in low version of the instrument cluster follow the following. Getting the timing right for moving between tests is tricky (longer or shorter than 1 second between pushes of the trip button determines whether you are moving between tests or subsets of tests.

    You want to unlock the tests *at test 19" and then go to the temp reading at test 7.


    ----------------------------

    Procedure: Press and hold (approx. 5 s) the trip recorder reset button with ignition swith on to at least the accessory position 1 "ON" until "__tESt__1._" appears in the instrument cluster display.

    The corresponding test (system test corresponds to test 2 "__tESt__2._") can be selected by pressing/releasing the button again within 1 second.
    The first subfunction of the test selected then appears after approx. 1 second. The subfunction (the system test has no further subfunction) of the corresponding test can be selected by pressing the button again. Since there are no further subfunctions associated with test 2 (system test), the system test is triggered after the "__tESt__2.0" display appears and the trip recorder button is pressed.

    If the test is a locked test (test 3 to 21) the lock is released by pressing the trip recorder button when "_L_oFF" appears in the display at test 19. The display then jumps to test 0 so that the corresponding test can be selected by briefly pressing the button.

    Test No. / Function

    1 Identification Instrument Cluster

    2 System test

    3 SIA data

    4 Current consumption values in l/100 km and l/h

    5 Range consumption and current range

    6 Fuel tank content values

    7 Coolant temperature, outside temperature, current engine speed, current road speed

    8 ADC values (system voltage, voltage at left and right lever sensor, voltage at photo transistor and BVA, voltage at coolant and outside temperature sensor)

    9 System voltage terminal 30 in volts

    10 Read out country-specific code

    11 Read out units (AM/PM or mm.dd/dd.mm) etc.

    12 not used

    13 Triggering acoustic signals

    14 Read out of error bytes (self-diagnosis)

    15 Display of I/O port statuses

    16 free

    17 free

    18 free

    19 Locking and Unlocking Test Functions

    20 Entry of a correction factor for average consumption

    21 Reset instrument cluster (software reset)

    0 End of test, the test mode can be quit with this function.


  11. #11
    Craig in Canada
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    Re: Interresting - I can't remove my oil filler cap

    Yes, yes, you're correct of course. For whatever reason I thought the OP had an I6 but re-reading his post I don't see any indication of that.... A momentary lapse in reason, I suppose.

  12. #12
    vcondis
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    Thanks everybody

    Thanks everybody for your input,you are making some very good points and have given me a lot of very useful info and food for thought. I will keep an eye on this,check on some of the things you suggested and report back if I have some new info.

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    Re: Cold weather oil cap condensation.

    Do you think that the engine is not warming up as fast as it should compared to others? If so, check for a stuck open thermostat.
    Cheers!
    Robert


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