head gasket or piston rings?

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Oct 26, 2011 | 08:59 PM

#16

Cherockee

CF Veteran

Joined: Aug 2010

Posts: 1,168

Likes: 4

From: Williamsport, Pa

Year: 1997

Model: Cherokee

Engine: 4.0L

The pressure in your crankcase is only coming from one place, a cylinder. It would be difficult to know for sure wether it's from rings or head gasket. The head gasket is the most likely place, but if you pull the head and there are no obvious "burn through" from the combustion chamber to an oil passage then you've probably got broken rings. Have you done a simple compression test yet? We could keep guessing but this will need some more data to be sure...

Oct 26, 2011 | 09:36 PM

#17

highmileage

CF Veteran

Joined: Oct 2011

Posts: 1,268

Likes: 1

From: Bakersfield CA

Year: 1990

Model: Cherokee (XJ)

Engine: 4.0

valve seals and wasted valve seats could also be the culprit. Going that direction though,a head gasket will be in order as well.

Oct 26, 2011 | 09:48 PM

#18

cruiser54

::CF Moderator::

Joined: Aug 2011

Posts: 43,971

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From: Prescott, Az

Year: 1990

Model: Cherokee (XJ)

Engine: 4.0

Quote:

Originally Posted by Cherockee

The only way combustion pressure gets down to the crankcase is past the rings. It's not difficult to know. Do a dry/wet compression test.

Head gasket lets combustion pressure pass from one cylinder to the adjacent cylinder.

Oct 26, 2011 | 10:40 PM

#19

Spoonman

Seasoned Member

Joined: Nov 2010

Posts: 279

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From: N.Y.

Year: 1999

Model: Cherokee

Engine: 4.0 L

Quote:

Originally Posted by cruiser54

Quote:

Originally Posted by Spoonman

I don't think that worn rings would raise crank case pressure.

Most certainly will. The cylinder pressure goes past the rings and pressures up the crankcase. That's why it's caused "blow-by".

A dry, then wet compression test will determine if it's rings.

To the OP: Can you feel the pressure or are you just getting oil in the air cleaner?

Yea my bad.If I had thought about what I was saying I wouldn't have said it.I hate giving bad advice srry about that.

Oct 27, 2011 | 05:53 AM

#20

cruiser54

::CF Moderator::

Joined: Aug 2011

Posts: 43,971

Likes: 1,579

From: Prescott, Az

Year: 1990

Model: Cherokee (XJ)

Engine: 4.0

Quote:

Originally Posted by Spoonman

Yea my bad.If I had thought about what I was saying I wouldn't have said it.I hate giving bad advice srry about that.

You are forgiven. LOL

Oct 27, 2011 | 03:34 PM

#21

Cherockee

CF Veteran

Joined: Aug 2010

Posts: 1,168

Likes: 4

From: Williamsport, Pa

Year: 1997

Model: Cherokee

Engine: 4.0L

Quote:

Originally Posted by cruiser54

Head gaskets will let pressure pass from the combustion chamber to where ever it burns through to. It's not always another cylinder, sometimes its to an oil passage or a collant passage, the latter being the most common. I still support a compression test, but it will not be a "tell all" unfortunately.