The YJ (242) just got an oil change last week and now its blowing oil into the air filter and leaking outta the filter box. The oil pressure gauge has been quite eradic for at least a year, bouncing from 0, up to 40 and back down constantly. Now it reads at just above forty all the time since the change, even though its probably already blown out a quart. Blow-by? Fawked piston ring? whats the deal? PCV?

blow by on a 4.0 is normal, but a quart, I don't know about that. Some is expected, but when it gets too much, you gotta do something about it. Its mostly caused by the vacuum hoses being clogged, and the gromets on the valve cover deteriorating and not sealing properly. There is a real good write up about it at www.jeepnorthwest.com. Read part one and two. If you change your oil regularly, your valve cover should be in good condition and pcv won't be clogged too bad. Also, your gauge is most likely doing that because the oil pressure sending unit is all done. They are like 15 bux for a vehicle with gauges and its right next to your oil filter.

Californian, you flame a new guy for accidently starting a thread trying to intoduce himself.. and you dont even know what causes blow by....when you get into high school you may want to take a basic automotive class... But I will try and be helpful and let you know blow by is caused by compression getting past the top or compression ring on the piston, pressuring up the crankcase more than the PCV can handle, high milage, cracked or stuck rings are just a few of the reasons..Spend less time flaming people and more time pulling/rebuilding your motor HTH...and so I can fit in by being a rude asshole :flipoff: :flipoff: :flipoff: :flipoff: :flipoff:

but at least his was a tec question you fawkin newbie
yea he flamed you so what at least he had enought sence to post his hello and introduction in the proper place unlike you who could not even read the rules and follow them:flipoff2:

Geez, Chris.... If you're going to quote a joke in your sig line, at least get it right!!! :flipoff2:

Paul (as 'on topic' as the rest of this asinine thread)

Originally posted by rustycj
but at least his was a tec question you fawkin newbie
yea he flamed you so what at least he had enought sence to post his hello and introduction in the proper place unlike you who could not even read the rules and follow them:flipoff2:
Maybe you did not read or are unable to interpet my post I mistakenly started a new thread while attempting to place my hello post in the proper place.. If you cannot understand that then :flipoff:

A little tip, don't go starting a bunch of crap with everybody and throwing the :flipoff: all over the place. Regardless of what happened you are just going to piss everybody off if you keep this up and nobody will end up taking you seriously.

Now, back to the original question: The best way to deal with blowby on a 4.0 is to just get it all over with at once. Peacemeal is just going to cause a lot of frustration that you don't want. Get yourself a new PCV valve (they are cheap) and pull the valve cover off. Give it a really good cleaning and get all of the crap out of there. Clean up all of the hoses and if they don't get squeeky clean, just replace them for cheap insurence. I had the same problem with my gauge too, just the sender unit acting up.

Like everyone said, some mild blowby isn't a huge deal, but if you really have a quart coming out of there then it sounds like your rings are wasted. For just a bit the above method should help things out, I've done it a few times before on different rigs. Good luck