2000 BMW 740 valves

Tiny
CMBARRA
  • MEMBER
  • 2000 BMW 740
  • V8
  • 2WD
  • AUTOMATIC
  • 200,000 MILES
Car smokes badly at start-up, oil on plug and in boot only recently. Happened all of a sudden.

How much should I expect to pay for a valve seal replacement. I know it is a big job.

CMB
Pensacola
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Wednesday, December 23rd, 2009 AT 11:45 AM

8 Replies

Tiny
HEIFETZ17
  • MEMBER
This is actually a very common issue on these cars. There's an oil separator valve (OSV) on the back of the intake manifold. This valve is a common weak point, and when it fails, you'll get smoke upon startup. The valve runs around $75 and some people have been able to replace them without taking the intake manifold off. I just removed the manifold on mine to make it easier.

The second option is the oil separator inside the left timing cover. This isn't as likely the cause, and it's also a fairly major job, as the lower timing cover and timing chain have to be removed.
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Wednesday, December 23rd, 2009 AT 7:30 PM
Tiny
CMBARRA
  • MEMBER
Thank you - funny thing you mentioned the OSV - is I ordered an oil separator valve yesterday and will be digging into that this week. Hope that is the answer.

Follow up -

I just find this start-up oil smoke too coincidental because It happened immediately after I changed valve cover and timing chain cover gaskets. NO smoke before. Could I have disturbed something of which I was unaware going in there? I must have. The osv doesn't seem to be close enough for me to have damaged.

Chris
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Thursday, December 24th, 2009 AT 5:25 AM
Tiny
DR. HAGERTY
  • MEMBER
The tube from the PCV plate forward has to turn 90 to get to the separator, that's where the break is.
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Friday, December 25th, 2009 AT 12:12 AM
Tiny
CMBARRA
  • MEMBER
Dr. Haggerty

I know this sounds dumb form someone who just changed the valve covers water pump, radiator and serp belts - but You said "The tube from the PCV plate forward has to turn 90 to get to the separator, that's where the break is."

I don't recall that. Can you describe it? Are you suggesting it broke somehow and that is likely causing the leak and smoking at start up? Where is it?

Thank you very much in advance.

CMB
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Friday, December 25th, 2009 AT 6:11 AM
Tiny
DR. HAGERTY
  • MEMBER
That is exactly right. There is a turn at the top of the valve and the drain tube should also be checked for blockage.

http://www.2carpros.com/articles/mitchell1eautorepair-car-repair-manuals
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Friday, December 25th, 2009 AT 4:54 PM
Tiny
CMBARRA
  • MEMBER
Dr. Haggerty Thanks again -

TWO FOLLOW UP THEN I HOPE NOT TO BOTHER YOU ANYMORE

1 - Is it likely I did this while changing the valve cover and timing cover gaskets? It wasn't smoking before.

2 - I ran the car, removed the oil dip stick, and there seemed to be no suction at the dip stick tube, which I thought was an indication of a bad OSV. Can the OSV cause this smoke with no suction on that test?

Thanks

CMB
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Saturday, December 26th, 2009 AT 6:13 AM
Tiny
DR. HAGERTY
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1. Yes, that's possibly what happened
2. You have it reversed, no vacuum indicates correct operation, vacuum indicates failure of the crank vent.
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Saturday, December 26th, 2009 AT 9:56 AM
Tiny
CMBARRA
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There is NO VACUUM when I remove the dip stick while engine runs. I can't feel anything.

Is that an idiot-proof check or could start-up smoke still be a bad OSV even when no vacuum is present?

Is there another way to tell if the OSV is bad?

Getting frustrated in Pensacola
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Saturday, December 26th, 2009 AT 3:18 PM

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