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  #1  
Old 01-21-2007, 12:13 AM
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Smelling "blowby", but does NOT use/leak ANY oil! ??

Hello again.

I have noticed for awhile now, on my way back into my neighborhood after driving 50-65 mph on the highway, I smell what smells like "vaporized" oil. Now, my car has 268K and it does NOT leak or burn any oil between the 3500 mile oil changes- which seems amazing for a 22 year old MB, with nearly 270,000 miles. I have drove up to 4000 miles before on one oil change, checked it and its completely full. So, I am wondering- whats this smell? Obviously its not burning oil since it is staying full, or it is so little, its not even noticable?

Perhaps something else in need of a change? Do these cars have PCV valves?

Thanks in advance!

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Old 01-21-2007, 01:37 AM
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What....car.



The diesel's have an oil seperator and run the breather hose right into the intake manifold. No pcv valve.
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Old 01-21-2007, 01:52 AM
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Sorry....

The car is a 1985 Mercedes 380SE sedan (gasoline) 3.8L V8.

Thanks again.
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Old 01-21-2007, 12:15 PM
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Look for valve cover gasket or head gasket leaking oil on the exhaust.
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Old 01-21-2007, 01:03 PM
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ditto.

tom w
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Old 01-21-2007, 02:41 PM
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Another source of blowby smell is from the valve cover breather system.
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Old 01-21-2007, 02:58 PM
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Oil burning off? Sure you don't have any leaks?
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Old 01-21-2007, 03:19 PM
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Thanks for the replies guys.... no, I checked... no leaks at all from the engine... when I turn the car off, it smells "clean" under the hood. Its only after driving at highway speeds, then I slow down I start to smell it and its definitely that "vaporized" oil type smell, but as mentioned, it (oil level) does not even go down at all on the disptick. It kinda smells like you are smelling the inside of the oil cap.

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1991 Lincoln Town Car Executive
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1973 Pontiac Grand Ville
(Prior MB's: 1974 240D, 1985 380SE, 1984 190D, 1993 400SEL)
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Old 01-21-2007, 03:21 PM
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Valve cover breather system?

Quote:
Originally Posted by MTI View Post
Another source of blowby smell is from the valve cover breather system.
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2004 Toyota Sequoia Limited 4wd
1991 Lincoln Town Car Executive
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1972 Chevrolet Caprice Kingswood Estate 9-passenger wagon
1973 Pontiac Grand Ville
(Prior MB's: 1974 240D, 1985 380SE, 1984 190D, 1993 400SEL)
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Old 01-21-2007, 06:14 PM
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The CCV (crankcase ventilation system) is awry somehow. I had a hard-starting issue on my Jeep that was temporarily resolved (for about 5k miles) by disconnecting the tube that connects the valve cover to the intake manifold. I plugged the manifold vac end. Smoother idle and easier starts resulted, but I had the smell you describe under conditions you described. Venting into the intake tube resolved the smell, and my idle is still smooth, but now it's hard starting again. I think blowby coats intake manifolds and makes for hard starting...

Anyway, check the lines from your valve covers. Make sure they go where they should and aren't cracked or disconnected.
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  #11  
Old 01-21-2007, 06:22 PM
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FWIW I had this problem on a 420SEL. Part of the smell came from small right side trans leaks hitting the exhaust. Some of it came from a squashed area of the rubber seal that runs across the top of the firewall. The blower intake is right behind that seal, and it is possible for engine smell to get pulled in by the blower if the seal is worn.

I would check the two breather hoses - one of the left front, the other at the right rear. And it takes only the most miniscule valve cover leak to cause and oil smell.
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Old 01-21-2007, 06:57 PM
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also:


on the 3.8L engine: Cam oiler tube holders will crack and leak oil. You may notice a black cloud of carbon upon accelerating usually.


it's common on that engine. cost $5 to replace. Be sure to order a new vavle cover gasket also
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Old 01-21-2007, 08:04 PM
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Quote:
Originally Posted by 86560SEL View Post
Valve cover breather system?
To prevent excess pressurization of the airspace area beneath the valve cover (usually due to leaking valves or valve seals) there is a ventilation/breather system that filters out any oil spray and vents out fumes, usually into the air cleaner.
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Old 01-21-2007, 09:20 PM
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Thanks... I will check that tube. I do not think is the the transmission either... it always stay full and there are no leaks/drips under the car at all.

Also, as mentioned, when I got out, I was smelling the "gaps" of the hood/fender and smell nothing, so that is why I ruled out valve covers. I would think I would be able to smell it then if it was that, but I do not.


Hard starting? That it is not. This is one of the "fastest starting" cars I have ever owned- whether cold or hot, it starts at the flick of the key. Also, there is no black smoke/soot even under heavy acceleration, even though I have never had it above 3000 rpms. No need to, because there is no more power at 3100 rpms, than they are at 2800 is seems. A power house its not. I guess 268K are catching up to it.
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Old 01-21-2007, 10:05 PM
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If not mistaken, your car draws fresh air into the cabin from the vents located at the cowling, the area where the windshield meets the hood. It wouldn't be very hard for engine bay vapors to get past some partially closed vent doors, especially at speed, and bring in that lovely aroma, especially if there is blow by happening.

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