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Discussion Starter #1

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On top of 14 and 15 you should change 1, 2, 3 times two and buy 9 and 10 and change 9 and 10 when/if you change your Thermostat, or change now if you are double jointed.



You could simply clean out the oil separators (1 and 2) but I advise to replace.
 

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Discussion Starter #3
how do i clean out #1 and 2 what do these do anyways
 

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Based on their appearance, 1 and 2 are cyclone separators. The oily air entering through hoses 14 and 15 comes in tangentially and swirls around inside like a vortex so that the heavier oil gets flung to the outside and drains down to hoses 9 and 10 back into the engine. The de-oiled air in the centre of the vortex escapes up through the top nozzle to the plenum. Unless BMW got fancy and installed internal check valves or similar, which should visible through the nozzles, I would just clean them well. Since cyclone separators depend on unobstructed drainage, I would also blow low-pressure air through the drain hoses to make site 9, 10 and 5 are not plugged.
 

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Discussion Starter #5
Based on their appearance, 1 and 2 are cyclone separators. The oily air entering through hoses 14 and 15 comes in tangentially and swirls around inside like a vortex so that the heavier oil gets flung to the outside and drains down to hoses 9 and 10 back into the engine. The de-oiled air in the centre of the vortex escapes up through the top nozzle to the plenum. Unless BMW got fancy and installed internal check valves or similar, which should visible through the nozzles, I would just clean them well. Since cyclone separators depend on unobstructed drainage, I would also blow low-pressure air through the drain hoses to make site 9, 10 and 5 are not plugged.
thanks for the expaination, how should i clean 1 and 2 warm soapy water?
 

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in for answer.
 

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I think they cost like $15 each.....whats your time worth to dink around cleaning something so cheap and will they really be clean inside when your done. Mine were nasty so i was glad i had bought new ones.

Follow the advice on the lower hoses and just buy them now so you have them for your t-stat replace which will certainly come.
 

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In terms of cleaning, they're just plastic pipes that get oil gunk in them, so anything that would dissolve and clean that away would suffice. As per the answer above, they're not some of the pricier parts to replace and tend to have quite an effect on the way the car drives, depending on how gunky they've got. Symptoms of issues include oil in the plenum after lifting the top and oil visible in the air intakes, under the filters or near the MAFs. Lots of info historically on here on the oil seperators.
 

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In terms of cleaning, they're just plastic pipes that get oil gunk in them, so anything that would dissolve and clean that away would suffice. As per the answer above, they're not some of the pricier parts to replace and tend to have quite an effect on the way the car drives, depending on how gunky they've got. Symptoms of issues include oil in the plenum after lifting the top and oil visible in the air intakes, under the filters or near the MAFs. Lots of info historically on here on the oil seperators.
+1 Brake cleaner should be great in cleaning these. Needless to say you have to remove them completely before ouich

Important - check hoses 14 and 15. If you haven't replaced them already you should.
 

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Was wary of brake cleaner, was unsure as I typed whether there was a chance it could harm plastic... Checked now and it seems to depend on which brake cleaner used.
 

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Be aware that when you renew the bottom oil seperator hoses you will have to remove the crimped on hose connector at the bottom of each hose. The only real way to get them off is to destroy them, and as most people don't have the proper crimps to replace them with its a good idea to use simple hose clips as per the ones used on the top of the same hose, item 11 here.

Order 2 of these extra to use on the bottom of the new hoses
 

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Agreed ----^
 

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Discussion Starter #13
so i went to the dealer today to order some parts got some 10-60 tws 15$, windshield trim 50$, dash trim pieice 33$, shadow chrome wheel touch up paint 35$ and wanted the to oil seperator hoses he said 60$ each, amd 150$ for each oil seperator,are they crazy, i passed on them and i guess i'll order them from pelican or some other cheaper site.
 

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Personally I wouldn't bother replacing the oil separators. They're just simple plastic cones really. Get some really powerful degreaser, some of that driveway degreaser you can get from local auto factor should so.. wash them up a bit and then chuck them in a bucket of that stuff for a couple of hours and that should do it.

I never repalced the bottom hoses either, I'd only swap them out if they are squishy really. The top hoses tend to get much worse. I'm also not that convinced the top seals for the separators into the cover need to be changed either. This part of the system is not under particularly high pressure so I don't think it makes much difference whether or not they are replaced. If they are clogged it definitely will and the top pipes being squishy will as they can collapse during operation and cause issues.

I'd clean things out and stop there personally..
 

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Since I believe the M5 is unusual in not having an intake manifold vacuum supplied PCV/CCV system to keep the crankcase at slight vacuum all the time, it seems it relies simply on the slight vacuum in the plenum to pull air out of the crankcase through the separators and keep it slightly negative. The degree of vacuum in the plenum depends solely on the pressure drop across the air filters, which depends on the air flow through them. This surprises me as the air flow at idle and low load is low so the plenum will be damn near atmospheric pressure. But I suppose the piston ring blow-by pressurizing the crankcase will also be low. Maybe M5's had such good ring sealing, BMW figured they didn't need PCV/CCV? Could the lack of a PCV/CCV system explain the reputation M5's have for higher than normal oil consumption? Seems to me if you had leaking valve stem seals for example, a crankcase held at negative pressure all the time would reduce oil leakage.
Also, maybe the use of low pressure-drop filters like K&N reduces the effectiveness of the separator system, since it reduces the vacuum in the plenum.
I have oil in the plenum and the only problem I can find with the separator system is a bit of crud build-up in the interior of the two separators. They are not plugged at all. Blowing down the separator drain lines gets the oil gurgle which I believe is normal so they are not plugged. So maybe it is just the crud reducing the effectiveness of the cyclone separation and oil drainage? I am starting to think the poster who said "just change them" has a point.
 

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For what it is worth, I had very gummy oil separator lines and replaced them last night. Two weeks ago I decided to do this because I noticed a lot of oil in the plenum. I was working on the vanos solenoids at the time.

Well, I had virtually NO oil in the plenum when I changed the oil separators. It seems I fixed the oil in the plenum issue when I fixed the vanos solenoids.

So, if you have a lot of oil in the plenum, you might want to clean your solenoids too.
 

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I never replaced the bottom hoses either, I'd only swap them out if they are squishy really. The top hoses tend to get much worse.
The bottom hoses are usually worse, as the bore is so much smaller. FWIW when i replaced my top hoses they weren't all that bad, but the bottom hoses had virtually collapsed in on themselves and were duly changed when the stat was done
 

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The bottom hoses are usually worse, as the bore is so much smaller. FWIW when i replaced my top
hoses they weren't all that bad, but the bottom hoses had virtually collapsed in on themselves and
were duly changed when the stat was done
+1 --- Spot-on!

Regards,
Alan
 

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Sorry for bringing up an old post... but...

The top hoses 14 & 15 have gone very soft on mine, I haven't checked the bottom ones.

I called the Stealer for a price and was told I need to change 5 hoses, of which I can now see there they are (This was one of my questions), but also to change the 2 Valves @ £55 for the 2, I take it he is referring to the plastic cones and as previously stated just clean them?

Just after some clarification please.

Also can someone expand on the thermostat, when should one change it and what sysmptoms would one get? My car's running fine, but just thought some preventative maintanence may not go amiss, especially as I have a 900 mile round trip in 3 weeks when attending the Le Mans 24 Hours Race!

Steve
 

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No real interval on thermostat

When they go, they fail open so the car doesn't reach full operating temp. Run the OBDII test #7 (do a search for secret menu test & there is a step by step if you haven't done before). When the car is up to temp, you should see it running 79c up to say 85c in traffic. If it is failed open, won't get above 79.... of course that's unless the weather is already warm where you are. Harder to determine during the summer.

Lots of members have done the DIY, but make sure to replace the lower oil hoses at the same time because they are nearly impossible to get to...huge pain, but with thermostat out of the way much easier.
 
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