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  #1  
Old 09-24-2009, 04:46 PM
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85 300D oil pressure!

my 300D incessantly leaks oil through every seam on my camshaft cover.
i replaced the gasket, but eventually i get oil blowout from the gasket,
the filler cap, even the air filter hose. im wondering if the pressure is too high.
i leak a few drop to a splash every where i go.. any guesses?

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  #2  
Old 09-24-2009, 04:51 PM
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Blowby?!

Quote:
Originally Posted by trigger View Post
... im wondering if the pressure is too high.
... any guesses?
I'm not an expert, but I'd guess you have a lot of blow-by gases built up in the crank case. Maybe a sign of worn rings... With the engine running (idling) carefully openup the oil filler cap - I mean carefully!!!! In your case it may be trying to fly off... so be forewarned.

Others may suggest more checks.
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Old 09-24-2009, 05:10 PM
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^Agreed and how much oil is in it?
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  #4  
Old 09-26-2009, 11:12 AM
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oil leak

i usually read about a quart lower than normal...
is there any other place that might allow pressure to build up?
the air intake, or maybe oil return, or just a clogged oil filter?
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Old 09-26-2009, 11:16 AM
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How's your PCV system?
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  #6  
Old 09-26-2009, 03:43 PM
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pcv system

im not sure how my pcv system is. what should i be looking for? oil separator trouble?
the haynes manual says" the pcv system is virtually maintenance free"

alternatively, could the vacuum diaphragm on my egr valve give me oil around the
cam cover gasket and in the air filter?

thanks
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Old 09-26-2009, 05:01 PM
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The PVC system on my 84 300d consist of a Hose coming off the Valve cover going into an Oil Separator in the Air Filter Housing. The Blowby gets sucked into the air intake while the oil goes into the separator and is supposed to go back to the crankcasel.
While amost maint free the hose can become restricted due to crap build up andyou cannot defy physics.

The hole in the Valve cover that the Hose attaches to is less han 1/2 inch in diameter. Only so much volume of Blowby can pass through that hole. If there is too much Blowby volume to pass through the hole the crankcase pressure will rise.
If that pressure is not relieved it will start looking for an easy way to get out and start pushing the Blowby out from under things.

My Father owned a gas engined Car that had worn Exhaust Vlave Guides/Stems. If you did not drive the car without the Oil filler/breather cap off it pushed Oil out from between the Oil Pan Gasket; resulting in a big mess.

What can you do about it?

Make sure your Hoses are un-restricted.

Inside of the top of the Valve Cover is a baffle to help keep the liquid Oil from being pulled in easily. Check that to be sure it is not plugged.

If the Blowby is being caused by worn Piston Rings the only cure is an Engine Overhaul.
If sticking Piston Rings it may be possible that Marvel Mystery Oil could unstick them as per this thread. However, be sure to avoid any sort of hydraulic lock by allowing time for the Oil to pass by the Piston Rings and crank the Engine without the Glow Plugs or Injectors on so as to blow out any excess Oil.
Compression Test...how low is low.....

If it is worn Valve Guides/Stems with the exception of replacing the Valve Stem Seals the only cure is to rebuild the Cylinder Head.

Note: Replacing the Valve Stem Seals on my Fathers car would not have helped as they were just little rubber umbrellas with a hole to slide over the Valve Stem; designed to deflect Oil away from the Valve Stems.
On the Mercedes they are actually real seals. However, new seals may not work if the Valves can be wiggled sideways too much due to wear. But, at least the Valve guide seals cost around $25.
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Old 09-26-2009, 08:37 PM
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if it was the case that i have worn piston rings, wouldn't i notice a loss of power or efficiency: im still getting 26+ mpg with fine acceleration...
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Old 09-26-2009, 09:52 PM
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My guess is a lot of blowby, but theres no harm in checking the pcv. It doesn't matter where the blowby is coming from in the case of oil leaks and blown out gaskets. The pressure is definitely not too high, the oil pump is operated by the timing chain, it's impossible to put out too much pressure.
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  #10  
Old 09-26-2009, 10:17 PM
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Run it a quart low

Quote:
Originally Posted by trigger View Post
i usually read about a quart lower than normal...
is there any other place that might allow pressure to build up?
the air intake, or maybe oil return, or just a clogged oil filter?

I had some similar issues and here's what I found:
  1. Check valve at the bottom of the oil seperator return tube seemed to be blocked. I confirmed this by filling the tube with clean oil (air cleaner and seperator removed). The oil did not drain. I applied a little compressed air and the oil begin to flow. I was doing an oil change and actually added a full quart of oil down that return tube. It seemed to flow faster as I went along. I now add 4 oz of clean oil that way every time I do an oil change by simply removing the breather hose off the air cleaner and using a funnel. If you add too much, you can overflow the oil seperator and get oil into the intake manifold leading to hydraulic lock which is a real pain to clear (ask me how I know)!
  2. Beginning several years ago, I observed more leaking and spots after an oil change. I always added the new oil to the top notch of the dip stick as recommended. This would continue until the oil level was half way between the two notches. This loss of oil would occur relatively fast and then the leaking would slow and never reach the lower notch before the next oil change. I no longer fill to the top notch and stop at the middle of the two notches. This is about one quart less than full. It leaks a little but not much and who's doesn't at 200k + miles? If you want a theory (unproven), I'd suggest I now have a larger air volume in the crankcase and thus a lower air pressure when means less leaking.
  3. My PCV system is disconnected as per Brian's post. Great improvement in performance but didn't change the oil loss rate.
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  #11  
Old 09-27-2009, 10:10 AM
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Quote:
Originally Posted by trigger View Post
my 300D incessantly leaks oil through every seam on my camshaft cover.
i replaced the gasket, but eventually i get oil blowout from the gasket,
the filler cap, even the air filter hose. im wondering if the pressure is too high.
i leak a few drop to a splash every where i go.. any guesses?
There are only four attachment points for the cover.........insufficient to do the task unless everything is perfect. Therefore, you must tighten the four nuts to 11 lb-ft.........in steps.........to guarantee no leaks.

The oil filter cap will leak unless the gasket is relatively new.

The air filter hose can also leak if it's old........needs a good grip and a good clamp to avoid any slight bit of oil.

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