Blow by, PCV, etc.

[Darin]

I followed some posts last week on oil in the air cleaner, PCV valve working correctly and then happened to notice this weekend that i had a bunch of oil in my air cleaner!!!

It wasn't there a month ago when I did a full tune and spark knock kit job. ( i replaced PCV and the gummed up hose.)

I have no oil smoke at all on a cold start, and 108K on a what seems to be strong motor. Could it be that the PCV valve is defective? I think someone metioned the steel tube coming out of the block that hoses to the PCV valve could be blocked. Any trick to checking that?

Any advice would be appreciated. I have done all the work since I've had it about 3 months except a Jeep dealer tuned my carb on a scope once anfter my tune up. His only comment was I had bad blow by. Without a leak down or compression test how would he know??? Am I missing something obvious?

Thanks for any input.

[Bnjnz]

i shot the metal tubing with som e carb cleaner when i changed my PCV valve. i thought this might clear any build up or debris left. try this and it might help

benjamin
1991 GW

[Jowersgd]

I've been told the same thing, but I have no oil burning and have never had a compression test and only 76K. Changing the pcv and the rubber hoses to and from it helped and I haven't had any oil in the air cleaner for months. Bob Barry said a while back in a post on a similar topic that this sort of blow by isn't that big of a deal and you can keep on trucking for many miles before a rebuild is necessary.

[homebru420]

I've been having blowby for sometime now and thought I'd be in for a rebuild sooner or later...I even tried new PCV valves, new hose pieces, and carb cleaner in the metal pcv tube from the manifold...still had blowby and got real nervous.

However, this weekend while doing a manifold swap I completely unscrewed the pcv air out tube from the rear of the manifold and found the very bottom of the tube (threaded part) was completely clogged with what appeared to be asphalt...probably from oil blowing up and scorching over time.

I recommend pulling the PCV tube right out of the manifold and checking it...I had to ram a punch through just to clean it out. Basically just get a wrench down on the base and unscrew after several squirts of pentrant. Mine's an 89 so I'll assume you've got the tube with the 90 degree bend in it...in order to get it off, you need to remove the EGR valve if yours still has it...that tube won't make a full rotation with the EGR on. Hope this helps.

[Darin]

homebru420,

It helps a bunch. I have an 89 GW as well. Thanks for the info, I'll give it a go this evening. (Yes I still have an EGR. A new one from the spark knock upgrade.) :D

[Jowersgd]

Homebru, your post is music to my ears. I'm looking forward to checking out my pcv tube. Hopefully that's all it is.

[Langdon]

If you have a length of hose, just hook it to the PCV fitting and try blowing into it...you can tell if it's blocked and really needs to be pulled.