CherokeeMedic

Can any one help me with the issue I'm having? My 1990 Jeep Cherokee 6 cylinder engine. has excessive blowby and is causing a leak. I recently replaced the head because it was cracked. Now I'm getting oil into my air filter and leaks on down. I also unclogged the CCV (crankcase ventilation), but it has not solved the problem. Any one has any other solutions to this problem I'm willing to listen.

Thanks
Juan

Jamie57

Hate to tell you this but the only way to fix blowby is to rering the pistons. There is no easy cheap fix for this.
Even with your new head I'd bet if you did a compression test you be below the minimums stated in the manual.
That blowby is actually combustion gases BLOWing BY the rings into the crankcase. It has to go somewhere as the oil pan and valve cover were not intended to be part of the combustion chamber. Sooooo it goes out your PVC (Positive Crankcase Ventalation or Valve)) into your filter airbox, and drags a bunch of oil with it.

jd4x426

do a compression test and post the results then we can help you a little better

ShadowAngel

Read an article about blowby on the cherokee (and oil on the air filter) being a pretty normal thing. Gave a part# for some grommets and vacuum hoses from the dealer that supposedly fixes the problem.. You should be able to find it with a google search.

mike37

read this
http://jeep.off-road.com/jeep/articl....jsp?id=257985

ShadowAngel

That's it. I need to do that on mine.. changed the air filter for the first time yesterday and found just a bit of oil on the old air filter.

Jamie57

Never heard of that as a problem. Hope they fixed it so my 98 doesn't do that.
I know my 91 did it but I also know the short block has over 300k kilometers on it so I expected blowby.
Hmmmm just a bad plumbing design.

mike37

all engines build crank case pressure
if it cant release it it needs to go some were
depending on haw the oil is slung and the position of the breather
if something gets clogged the oil will go some were

Jamie57

Actually no Mike the oil SHOULDN"T go somewhere. Yes the blowby gases should but it should not pick up oil along the way. I've built many a race engine along with untold tens maybe 200 stockers that don't blow LOTS of oil let alone any when they get old. Yeah a little, enough that you need to change the crankcase filter once in awhile but to have it pool in your air cleaner box?
I think it was a bad design because the kits on the other websites only need to go to the time Chrysler was taking over. After that somebody fixed it.

mike37

yes it was a bad design
depending on how the oil is slung and the position of the breather
if something gets clogged the oil will go some were

what I was saying is not all engines will do this because of design differences

and all will build pressure and if the place the pressure is released has lots of oil oil will blow out

Jamie57

I think we are agreeing on the same thing. I just call it a bad design that was fixed later.

mike37

yes pore valve cover design

350 with cheep valve covers will blow oil cus the don't have any shielding
by the breathers