blow by

[josue estrada]

So the 95 old jeeper is getting minor blow by. It is very small amount, not even a quarter of the air filter. Is this the beginning of the end of the short lived 152,000 mile engine? If not what can I do to fix this issue.

 

[kingmega]

blow by is never a good thing i have seen some go for a long time with it and some not. rings ware out and oil get's past them into places it should not be

 

[superj]

and oil on your filter is not necessarily blow by. are you running the i6 or a 4 banger? the i6 doesn;t use a pcv valve so if you don;t keep an eye on the two lines on top of the valve cover and keep the fittings and stuff clean, you will get oil blown onto your filter. i cannot remember what makes it happen but its normal when something is dirty. have to google it or see if someone else can remember what it is

 

[Jester32]

If the vacum line to the valve cover leaks the crank case will spit it into the air filter. You need the crank case under vaccum. The hose to the air filter is just fresh air into the crank case.

 

[flatie46]

At that kinda mileage they've all got a little blow by. Don't let it worry ya, the Cherokee I had was pretty bad. It ran and drove fine and was plenty strong when I traded it. I believe it's still going.

 

[bugleboy]

If the vacum line to the valve cover leaks the crank case will spit it into the air filter. You need the crank case under vaccum. The hose to the air filter is just fresh air into the crank case.

crap... mine leaks from time to time... i need to get that fixed, im just now learning about blow by

 

[drivetrainsman]

most motors create pressure that is why it does it but if it is soaked with oil that is a blow by issue!

pcv (positive crank case valve) lets air out or vapors into the intake that's when the crank case get pressurized!

 

[superj]

We don't actually have a PFC valve, it's more like a 90 degree elbow

 

[bugleboy]

i foun this online, is this a valad way to help stop blow by or am i not understanding this correctly?

http://www.angelfire.com/my/fan/Catch_can.html

 

[bugleboy]

i do believe its a cherokee the person who made this is using it on by the installed picture, its an i6 that much i know

 

[drivetrainsman]

We don't actually have a PFC valve, it's more like a 90 degree elbow

the valve was an example of how the motor can get pressurized I know they are just elbows

 

[Bounty__Hunter]

'91+ Jeep engines don't have a PCV system, they use a CCV system (closed crankcase ventilation). There's a vacuum line from the intake to the valve cover to pressurized the crankcase and burn crankcase vapors. There's a 2nd line from the valve cover to the air intake to supply fresh air INTO the crankcase.

Find the line from the valve cover to the airbox. Pull it off at the airbox and check for vacuum. If bo vacuum or its blowing air, chances are the CCV system is clogged and working in reverse. Make sure the vacuum line from the intake manifold to the valve cover is in good condition. Find the restrictor orifice in the line to the airbox and make sure its not plugged with carbon. The orifice is either in the brass fitting screwed into the valve cover, or its in a plastic connector in the hose to the airbox.