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Alternative way to fix blowby than buying OEM parts ?

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dan89XJ

NAXJA Forum User
Location
Oregon
Well, my stocker 90 XJ has a nasty oily airfilter where that breather tube goes to in the air box. Well, I figured its the plugged PCV problem that all the 4.0's have. I have found a write up to fix the problem.. at:

http://jeep.off-road.com/jeep/article/articleDetail.jsp?id=257985

excellent info.. with part numbers. However.. I am wondering if there are other ways to fix this ? using diffrent parts and not OEM stealership parts. Something like.. a inline PCV and better hoses. And I'd like to simplify things under the hood.. Any ideas, other write ups, threads, pics ?

Oh, and if this belongs in mod tech.. I wont be offended if its moved.
 
I thought of using an electric vaccum pump to create continous negative pressure in the crankcase, like an indy or drag engine Admittedly, it's silly to propose doing this when you only turn 4000 rpm, but the indy cars turn 12,000, and they gain revs and horsepower from spinning the rotating assembly in a partial vacuum.

of course the crankcase vapors should be fed back into the intake plenum, not spit into the air. It would make for an neat experiment though. never seen this done on a jeep.
 
Napa sells the stock CCV system and its a litle cheaper than the dealer. My dealer actually price matched Napa the last time I bought the system!
 
I had a pretty bad case of this on my '88. Not only would the filter get soaked but there'd be a pool of oil in the bottom of the air box. I used a small drill bit to clear out the deposits in the orifice and sprayed carb cleaner through the tube. It was pretty amazing how much goo came out. Once it flushed clean, I put it back together and the air cleaner has been dry since. I also checked my compression and it was fine so I know the blowby was from the clogged ccv.

Assuming your compression is OK, you might try cleaning everything throughly. Take the valve cover off too and clean it inside, especially around the grommets for the tubes.
 
The small line from the valve cover to the intake gets plugged up pretty easy. This is the one that scavenges the vapors at idle (throttle closed), the large one works mostly at open throttle. If the small one is plugged and the throttle is closed, it creates a positive crankcase pressure, when the throttle is opened again, you get a surge. Sometimes it's just too much crankcase pressure for the system to handle (blowby), often it is the small line being plugged, that adds to the whole problem.
 
Does this fix work for the 91+ 4.0? I'm having a similar problem
 
I was wondering the same thing. Does anybody have the part numbers for my' 92? They are certainly not the same as in the Cherokee America article.
 
I used a piece of 5/16 fuel line about 18" long and replaced the smaller plastic line. It looks way cool and I was able to bend and shape it to route where I wanted it. My rear main is still thanking me.:smootch:
 
got mine for my 91 from teamcherokee.com for cheap. I had cracked boot leaking vac.
 
mcnamaag said:
I used a piece of 5/16 fuel line about 18" long and replaced the smaller plastic line. It looks way cool and I was able to bend and shape it to route where I wanted it. My rear main is still thanking me.:smootch:
Click to expand...

I have the same problem on my 90 XJ...but I have a K&N filter and a pool of oil on the ground whenever I parked.
I replaced that small hose from the vacuum to the valve cover with a thick wall rubber vacuum tube. Now it works perfectly and I no longer have any problems...
The small plastic tube is the problem...All the bends and such causes the evaporated gasses to recondense and clog at the bends. I figure it's not worth spending the $70 (at my dealership anyway) for something that wI'll just clog again anyway...so a $0.50 piece of vacuum hose fixed that...done deal!
Ed
web/gadget guru
 
Hmm I have a weird oil leak on my 88. It seems to be al over my Driver side LCA and on the Driver wheel well top then a puddle of it kinda right under the air cleaner. Maybe this is my problem too?
 
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