If you read around the links Bill posted it outlines where the common
leaks are that can cause the blow by.

Some other causes: If you trace the PCV line along the valve cover, you
will come to a 90 elbow. Make sure this hasn't collapsed.

Then continue on to the back of the engine on the PCV line and at the T
or solenoid thing behind the carb, you will find a line going to the
charcoal canister that sits 'way' down under the washer bottle on the
fender bottom.

At idle pinch this line to the canister closed. If the idle changes,
the canister is worn out and needs replacing. It is the gas tank and
carb float bowl vent and is needed.

When leaking, the canister basically shuts down the PCV system causing
the oil to blow into the air filter and a bad or surging idle.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

Micah wrote:
>
> I've seen this mentioned a few times on this forum as a possible
> diagnosis for a poster with a rough idle complaint, but have yet to
> find the solution... According to previous posts, it's "pretty easy"...
> But again, no one's mentioned the easy solution.
>
> 258 with a slightly rough idle and oil blowing into the air cleaner.
> Suggestions/ideas? Do I just need to find a good breather filter?

 

If you read around the links Bill posted it outlines where the common
leaks are that can cause the blow by.

Some other causes: If you trace the PCV line along the valve cover, you
will come to a 90 elbow. Make sure this hasn't collapsed.

Then continue on to the back of the engine on the PCV line and at the T
or solenoid thing behind the carb, you will find a line going to the
charcoal canister that sits 'way' down under the washer bottle on the
fender bottom.

At idle pinch this line to the canister closed. If the idle changes,
the canister is worn out and needs replacing. It is the gas tank and
carb float bowl vent and is needed.

When leaking, the canister basically shuts down the PCV system causing
the oil to blow into the air filter and a bad or surging idle.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

Micah wrote:
>
> I've seen this mentioned a few times on this forum as a possible
> diagnosis for a poster with a rough idle complaint, but have yet to
> find the solution... According to previous posts, it's "pretty easy"...
> But again, no one's mentioned the easy solution.
>
> 258 with a slightly rough idle and oil blowing into the air cleaner.
> Suggestions/ideas? Do I just need to find a good breather filter?

 

If you read around the links Bill posted it outlines where the common
leaks are that can cause the blow by.

Some other causes: If you trace the PCV line along the valve cover, you
will come to a 90 elbow. Make sure this hasn't collapsed.

Then continue on to the back of the engine on the PCV line and at the T
or solenoid thing behind the carb, you will find a line going to the
charcoal canister that sits 'way' down under the washer bottle on the
fender bottom.

At idle pinch this line to the canister closed. If the idle changes,
the canister is worn out and needs replacing. It is the gas tank and
carb float bowl vent and is needed.

When leaking, the canister basically shuts down the PCV system causing
the oil to blow into the air filter and a bad or surging idle.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

Micah wrote:
>
> I've seen this mentioned a few times on this forum as a possible
> diagnosis for a poster with a rough idle complaint, but have yet to
> find the solution... According to previous posts, it's "pretty easy"...
> But again, no one's mentioned the easy solution.
>
> 258 with a slightly rough idle and oil blowing into the air cleaner.
> Suggestions/ideas? Do I just need to find a good breather filter?