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EricFromCT, Technician
Category: Lincoln
Satisfied Customers: 3417
Experience:  ASE, Ford Lincoln Mercury Senior Master, Diesel, Kia Professional Elite
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2012 MKZ 2.5 hybrid. Engine has excessive blow by. When the

Customer Question

2012 MKZ 2.5 hybrid. Engine has excessive blow by. When the engine is running and the oil cap is removed it has an extreme amount of pressure coming out.
Submitted: 10 months ago.
Category: Lincoln
Expert:  EricFromCT replied 10 months ago.

Hi. Does the vehicle have any other concerns like excessive oil consumption or blue smoke out the exhaust?

Customer: replied 10 months ago.
No oil consumption and no smoke. It does however push oil through the sensor in the valve cover. By the way it only has 38,000 miles on it
Expert:  EricFromCT replied 10 months ago.

It is more common to have the valve cover leak and cause oil to be where the sensor is.

Customer: replied 10 months ago.
The valve cover gasket is not leaking. The pressure is forcing it out at the sensor at the top of the cover and it sprays all over the engine.
Expert:  EricFromCT replied 10 months ago.

Have you checked the oil level?

Customer: replied 10 months ago.
initially it was about a quart and a half over full. I then changed the oil and filter. I also removed the intake manifold and there was oil standing in it and the throttle body was saturated also. Cleaned them both and restarted and got the same results. When the intake was off I also removed, inspected, and cleaned the crankcase vent assembly.
Expert:  EricFromCT replied 10 months ago.

How did it get overfilled? Perhaps the piston rings became saturated with oil and now the compression ring(s) are stuck getting you a lot of pressure in crankcase. Dont see how else pressure would be there. Sounds like you have excessive blow by.

Customer: replied 10 months ago.
I think the cars owner may have overfilled it. I did a compression check and all the cylinders are approximately 100 psi. I looked in Alldata and Mitchell but couldn't find specs for compression. If the compression rings are stuck, what could have caused it, and how do I unstick them?
Customer: replied 10 months ago.
Are you still helping me?
Expert:  EricFromCT replied 10 months ago.

Yes I am. I have checked the shop manual and they do not say that you can do a compression check on the 2.5L hybrid because it has a different cycle called atkinson cycle engine which allows for low compression so the engine can start easier when switching to hybrid and gas.

Expert:  EricFromCT replied 10 months ago.

So I doubt the rings are stuck. I wonder if taking the plugs out and pulling the injector connectors and cranking it for a while may dry out the cylinders. Perhaps the walls are just really washed with oil.

Expert:  EricFromCT replied 10 months ago.

I am just checking in and will be back online after 8pm.

Customer: replied 10 months ago.
I'll try pulling the plugs and disconnecting the injectors and cranking it over as you suggested today and get back to you.
Expert:  EricFromCT replied 10 months ago.


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