Wranglerjeep1

I'd bet money you have a Vac leak...I've been down this road so many times it
not even funny. I doubt your cat has anything to do with your problem.

Brian
88 Wrangler

Wranglerjeep1

I'd bet money you have a Vac leak...I've been down this road so many times it
not even funny. I doubt your cat has anything to do with your problem.

Brian
88 Wrangler

Wranglerjeep1

I'd bet money you have a Vac leak...I've been down this road so many times it
not even funny. I doubt your cat has anything to do with your problem.

Brian
88 Wrangler

Mike Romain

That could be very likely a problem.

I don't know the relation to back pressure and 'blow by' but a partially
blocked cat is for sure a power killer. I would really suspect that
from your symptoms.

The 'normal' reason for the oil blowing into the air filter in that
engine is a worn out emissions or charcoal canister. It is at the age
where they up and die.

I would first get the cat fixed and see if the oil blow immediately
stops. If it doesn't, then you can trace the PCV line to the rear of
the carb making sure the rubber elbow at the back isn't soft and mushy
so it can collapse. Then at the rear of the carb, there will be a
solenoid thing or preferably a T fitting with one line going way down
under the washer bottle to the charcoal canister.

At idle pinch this line to the canister closed. If the idle changes,
the canister purge valve is worn out and you need a new canister.

The canister is only supposed to purge when the engine is hot and at
speed. The 'on' signal is ported vacuum via the CTO valve.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

howard.phelan@us.army.mil wrote:
>
> Well this morning, after driving to work, I checked under the hood
> because I had heard an fairly loud hissing noise when I applied gas.
> Looking in the air cleaner I discovered a lot of oil that had come in
> the backside of the air cleaner. In fact the brand new air cleaner on
> that side was soaked and the oil was puddled about 1/4 inch deep in the
> back. Some was even dripping out the air intake of the air cleaner.
> I had just had the engine tuned with new plugs, wires, dist. cap, fuel
> filter, and PCV valve. When I showed it to the mechanic that did the
> work, he checked out the catalytic converter and discovered that it was
> quite damaged, as he could hear the ceramic inside rattling around when
> he shook it. His theory is that the converter is restricting airflow
> and therefore I guess causing back pressure which is causing the oil to
> come in from the backside of the air cleaner.
> I guess this sounds reasonable and could result in lack of power, and
> besides that, he recommeded a place other than his to do the converter
> work since they could do it cheaper than he could.
> Any thoughts? Maybe he owns the other shop, too!

Mike Romain

That could be very likely a problem.

I don't know the relation to back pressure and 'blow by' but a partially
blocked cat is for sure a power killer. I would really suspect that
from your symptoms.

The 'normal' reason for the oil blowing into the air filter in that
engine is a worn out emissions or charcoal canister. It is at the age
where they up and die.

I would first get the cat fixed and see if the oil blow immediately
stops. If it doesn't, then you can trace the PCV line to the rear of
the carb making sure the rubber elbow at the back isn't soft and mushy
so it can collapse. Then at the rear of the carb, there will be a
solenoid thing or preferably a T fitting with one line going way down
under the washer bottle to the charcoal canister.

At idle pinch this line to the canister closed. If the idle changes,
the canister purge valve is worn out and you need a new canister.

The canister is only supposed to purge when the engine is hot and at
speed. The 'on' signal is ported vacuum via the CTO valve.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

howard.phelan@us.army.mil wrote:
>
> Well this morning, after driving to work, I checked under the hood
> because I had heard an fairly loud hissing noise when I applied gas.
> Looking in the air cleaner I discovered a lot of oil that had come in
> the backside of the air cleaner. In fact the brand new air cleaner on
> that side was soaked and the oil was puddled about 1/4 inch deep in the
> back. Some was even dripping out the air intake of the air cleaner.
> I had just had the engine tuned with new plugs, wires, dist. cap, fuel
> filter, and PCV valve. When I showed it to the mechanic that did the
> work, he checked out the catalytic converter and discovered that it was
> quite damaged, as he could hear the ceramic inside rattling around when
> he shook it. His theory is that the converter is restricting airflow
> and therefore I guess causing back pressure which is causing the oil to
> come in from the backside of the air cleaner.
> I guess this sounds reasonable and could result in lack of power, and
> besides that, he recommeded a place other than his to do the converter
> work since they could do it cheaper than he could.
> Any thoughts? Maybe he owns the other shop, too!

Mike Romain

That could be very likely a problem.

I don't know the relation to back pressure and 'blow by' but a partially
blocked cat is for sure a power killer. I would really suspect that
from your symptoms.

The 'normal' reason for the oil blowing into the air filter in that
engine is a worn out emissions or charcoal canister. It is at the age
where they up and die.

I would first get the cat fixed and see if the oil blow immediately
stops. If it doesn't, then you can trace the PCV line to the rear of
the carb making sure the rubber elbow at the back isn't soft and mushy
so it can collapse. Then at the rear of the carb, there will be a
solenoid thing or preferably a T fitting with one line going way down
under the washer bottle to the charcoal canister.

At idle pinch this line to the canister closed. If the idle changes,
the canister purge valve is worn out and you need a new canister.

The canister is only supposed to purge when the engine is hot and at
speed. The 'on' signal is ported vacuum via the CTO valve.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

howard.phelan@us.army.mil wrote:
>
> Well this morning, after driving to work, I checked under the hood
> because I had heard an fairly loud hissing noise when I applied gas.
> Looking in the air cleaner I discovered a lot of oil that had come in
> the backside of the air cleaner. In fact the brand new air cleaner on
> that side was soaked and the oil was puddled about 1/4 inch deep in the
> back. Some was even dripping out the air intake of the air cleaner.
> I had just had the engine tuned with new plugs, wires, dist. cap, fuel
> filter, and PCV valve. When I showed it to the mechanic that did the
> work, he checked out the catalytic converter and discovered that it was
> quite damaged, as he could hear the ceramic inside rattling around when
> he shook it. His theory is that the converter is restricting airflow
> and therefore I guess causing back pressure which is causing the oil to
> come in from the backside of the air cleaner.
> I guess this sounds reasonable and could result in lack of power, and
> besides that, he recommeded a place other than his to do the converter
> work since they could do it cheaper than he could.
> Any thoughts? Maybe he owns the other shop, too!