Blow-by question

I know that blow-by has been discussed here a number of times, and it
seems that it is quite common in the 258's. I have talked to a few
people with 258's that have the problem and offered advice that I've
read here, all the way to changing the oil fill cap. My question is
this. How much is _too_ much? I've been using Lucas Oil Treatment, and
keeping the oil changed often. I've never had a vehicle with a blow-by
problem, and it kinda makes me nervous. So, is there a point when there
is too much blow-by, and if so, how much is it? I add _maybe_ 1/2 qt. a
week driving roughly 300 miles a week. 89 YJ, almost 120K. TIA, Dan

That usually means you have issues with the PCV system, they are
extremely touchy.

You can follow the line and as it turns to the back of the carb there is
a rubber elbow there that can collapse. Then there is a solenoid thing
behind there that can be replaced with a T fitting, they never worked
well and the fix is a T.

Finally off this solenoid thing, there will be a tube to the charcoal
canister way down under the brake reservoir. At idle pinch this like
closed. If the idle changes, the canister purge valve is worn out.
This will effectively shut down the PCV and cause blow by.

1/2 a quart a week is getting up there.

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

Daniel Paisley wrote:
>
> I know that blow-by has been discussed here a number of times, and it
> seems that it is quite common in the 258's. I have talked to a few
> people with 258's that have the problem and offered advice that I've
> read here, all the way to changing the oil fill cap. My question is
> this. How much is _too_ much? I've been using Lucas Oil Treatment, and
> keeping the oil changed often. I've never had a vehicle with a blow-by
> problem, and it kinda makes me nervous. So, is there a point when there
> is too much blow-by, and if so, how much is it? I add _maybe_ 1/2 qt. a
> week driving roughly 300 miles a week. 89 YJ, almost 120K. TIA, Dan

you should not have to add more than 1 qt per 1000 miles
looks like you exceeded this informal limit
note that not all oil loss may be due to pvc-
account for engine wear as well resulting in oil being combusted
if this second scenario should be your concern, then note you should not lose more than 1 qt of oil
between oil changes (assuming no blowby or leaks involved)

hth, pete

"Daniel Paisley" > wrote in message
...
> I know that blow-by has been discussed here a number of times, and it
> seems that it is quite common in the 258's. I have talked to a few
> people with 258's that have the problem and offered advice that I've
> read here, all the way to changing the oil fill cap. My question is
> this. How much is _too_ much? I've been using Lucas Oil Treatment, and
> keeping the oil changed often. I've never had a vehicle with a blow-by
> problem, and it kinda makes me nervous. So, is there a point when there
> is too much blow-by, and if so, how much is it? I add _maybe_ 1/2 qt. a
> week driving roughly 300 miles a week. 89 YJ, almost 120K. TIA, Dan
>

Mike Romain wrote:
> That usually means you have issues with the PCV system, they are
> extremely touchy.
>
> You can follow the line and as it turns to the back of the carb there is
> a rubber elbow there that can collapse. Then there is a solenoid thing
> behind there that can be replaced with a T fitting, they never worked
> well and the fix is a T.
>
> Finally off this solenoid thing, there will be a tube to the charcoal
> canister way down under the brake reservoir. At idle pinch this like
> closed. If the idle changes, the canister purge valve is worn out.
> This will effectively shut down the PCV and cause blow by.
>
> 1/2 a quart a week is getting up there.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's

What Mike said. That 258 is a good ol' motor, well proven. If you've got
leakage, look for a product called Tri-Seal.. good stuff, I've used it
in motors, hydraulics, power steering, transmissions, all with good
results. If it's burning oil, don't worry about it- it'll last about
forever if you keep the oil level up and don't pick on it too hard.

John

I found when I had pcv problems, oil would come out of the engine oil
dipstick....possible oil loss area, and cause other gaskets to leak. MIKE,
what do you think about replacing both pcv and the one in the back with a
oil breather cap?? I've changed to a webber carb and disabled all of the
emissions....would that help?? Also, bill previously mentioned something
about reattaching the fuel cannister as a fuel milage increase?? Any idea
about the problems associated with my removing the cannister all together?
Or should I reconnect it tothe webber, and if so how?? The webber
instructions were crap...
Thanks...you and bill are the jeep knowledge gods so far.....
Robb

--
Message posted via http://www.carkb.com

Well for starters today's carbs are designed to have a massive vacuum
leak at their base called a PCV inlet. Without this leak, it will run
really rich to the point of needed a smaller jet even.

Are you old enough to remember the old drip tubes that engines had so
all the oil that pukes out goes down onto the road instead of all over
the engine compartment? That is what is needed instead of a PCV
valve....

The canister is also part of this system. The canister is the air vent
for the gas tank. If the tank has no vent or the air filter on the
bottom of the canister gets blocked with dirt, then a vacuum will form
in the gas tank causing the engine to run out of gas.

I ran with the canister disconnected for a while until my wife started
refusing to drive in it because of the strong raw gas smell getting into
our clothes and hair.

So what flavor of Jeep and type of engine do you have?

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

"Robb S via CarKB.com" wrote:
>
> I found when I had pcv problems, oil would come out of the engine oil
> dipstick....possible oil loss area, and cause other gaskets to leak. MIKE,
> what do you think about replacing both pcv and the one in the back with a
> oil breather cap?? I've changed to a webber carb and disabled all of the
> emissions....would that help?? Also, bill previously mentioned something
> about reattaching the fuel cannister as a fuel milage increase?? Any idea
> about the problems associated with my removing the cannister all together?
> Or should I reconnect it tothe webber, and if so how?? The webber
> instructions were crap...
> Thanks...you and bill are the jeep knowledge gods so far.....
> Robb
>
> --
> Message posted via http://www.carkb.com