Do they go bad? Or do they get clogged? I am replacing the CCV and oil separator hose/tube. I see some oil in intake.
Does they oil separator drain back to oil pan? Can oil separator be flushed?
Thanks
1979 Chevy Camaro Z28
2000 BMW 540i, 6speed
2005 Chevy 2500 Duramax 4x4
The oil separator is mounted behind the timing chain. No history that they clog up.
Ed in San Jose '97 540i 6 speed aspensilber over aubergine leather. Build date 3/97. Golden Gate Chapter BMW CCA Nr 62319.
If you remove the front covers of the engine -for a timing chain guides job ?- then you definitely want to replace the oil separator "while you are there". Otherwise, just ignore it.
See the location of the oil separator on the M62TU engine, front covers removed
Last edited by Chedley; 08-02-2020 at 04:51 AM.
These OSVs do have a history of clogging. Search this site for catch cans on M62's and you'll find plenty of owners who are did work-arounds for their clogged OSVs. I was one of them.
There's a rubber connector at the bottom of the OSV that connects it to the a tube that drains the oil back to the sump. The bottom of the OSV is 1/4" or so wide, but the hole in the rubber connector is only 1/8" or less. That's where it can clog. I've also heard of old OSVs cracking and breaking while in the car.
I bought an '02 540-6 a few years ago with 150,000 miles. It was burning a LOT of oil and changing the CCV didn't help. It was a waste of money -- the diaphragm in the new CCV promptly tore because the real problem was a clogged OSV. (The CCV is meant to deal with air and oil vapor, not a steady flow of oil.)
When I was tracking down the problem and had the CCV off, I hooked a hose to the pipe under the intake that came from the OSV. When I sucked or blew on the hose, I heard the air gurgling through the oil in the OSV. It was so clogged it was acting like an oil carb -- adding oil to the CCV air flow instead of taking it out.
I installed an external OSV and solved the problem. No more oil burning and no blown CCV.
4 years later I had to do the chain guides. I checked and saw that the clog in the OSV was gone. That's because I'd been using variety of high-mileage (detergent) oils, AND changing the oil every 3,000 miles (even synthetic).
In short, I think the ill-advised long oil change intervals are the #1 reason why these OSVs clog.
Last edited by R Shaffner; 08-02-2020 at 06:09 AM.
Some have suggested that the OSV can be cleaned, or unclogged, by taking off the oil pan and running a wire up the tube. I tried that and it didn't work for me. I couldn't get the wire past the rubber connector to the clog.
Others have said they tried pouring some kind of solvent down the tube under the intake. I think that has a better chance of working, but haven't tried it. Prob worth a try if you're replacing the tube anyway and think your OSV might be clogged.
If you're just thinking about keeping it open and clean, then I suggest using high mileage oils every now and then, if not all the time, and changing the oil often.
Also, a little oil in the bottom of the intake is normal in these engines. If it isn't a puddle and you're not burning any oil, that you notice, then your OSV is probably working OK.
Last edited by R Shaffner; 08-02-2020 at 06:36 AM.
Thank you guys for the info.
1979 Chevy Camaro Z28
2000 BMW 540i, 6speed
2005 Chevy 2500 Duramax 4x4
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