90 Merc Wagon has oil coming from dipstick

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  #1  
Old 10-09-06, 10:31 AM
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90 Merc Wagon has oil coming from dipstick

1990 Mercury Grand Marquis Colony Park Wagon
170K miles
5.0L Fuel injected V8
All systems in reasonably good order and maintained. New plugs installed in the past year. New EGR valve in past two years.

Problem: Oil being forced out of dipstick, leaking onto exhaust manifold and causing smoke.

I have had to maintain the PCV system since owning the car. But this is the first time this problem has shown up. Have replaced the crankase filter element under the PCV valve in the past year.

Checked the PCV valve yesterday. Seems to be ok.

Checked the oil filler hose to throttle body input as well. Is clear, not clogged.

The next step was to pull the intake manifold and check all connections to it. I cannot get to the hose that goes from the PCV valve to the intake manifold. It seems to disappear behind the manifold where I cannot get to it. Might be clogged. but somehow I dont think thaht is the problem, since the PCV valve would probably just pop out given enough pressure from inside.

I believe this condition is likely caused by "blow-by".

As I understand this, pressure builds up in the crankase due to gas passing between the cylinder walls and the cylinders into the crankase. It is due to the age of the engine.

Maybe there is nothing to be done, but it came on suddenly, so I suspect it may have a cause other than just old age.

Any suggestions for troubleshooting would be most appreciated. Car is only run occaisionally for hauling building materials and to keep it going. Still very useful for her final purpose in life. Lots of sentimental value as well.

Thanks.
 
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Old 10-09-06, 10:52 AM
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I would check the pcv hose for sure. Just pull it off and see if you are getting vacuum there. If it's unclogged the engine will likely stall out. Next I would do a compression test [wet & dry]to see what's going on inside.
 
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Old 10-10-06, 07:17 AM
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Thanks for the suggestion, tow_guy.

I will do that. I get confused, though, which way should the vacuum be present? I was thinking it should be negative at the hose, that is, sucking into the hose toward the intake manifold, yes?

As for stalling, in the past I have had the engine leak oil from the pcv valve hole. It would push the valve and grommet out of the engine and oil would run down the back of the engine. But it would not stall as a result, so I am not sure what you were referring to when you mentioned stalling.

I fixed that condiiton about 2 years ago, but probably caused this new problem as a result, I suspect. (That assumes it is not just old age.)
 
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Old 10-10-06, 09:58 AM
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Suction would be away from the valve cover/pcv and towards the intake manifold. If you pull the hose off the pcv there should be a strong suction in the line and if the line is open, the loss of vacuum may be sufficient for the engine to stall or at least run very badly. If you pull the hose and can't feel any suction it's probably gunked up.
 
  #5  
Old 10-11-06, 01:46 PM
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Yup, got it. Thanks. Makes sense.
 
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