Anyone with the 14x3 round air cleaner notice oil fumes in the cab? I am positive it is coming from the crank case breather so I replaced it and the PCV valve and have also tried a few other different methods and I still am smelling oil fumes. I put the stock air box on yesterday and no more oil fumes. Anyone else have the same problem? Do you just live with it or is there a fix?

 

with the round air cleaner it doesnt have a port for the breathr...did you put a filter type breather on?

 

Yes it does have a port for the breather, it has 2 ports. From July until now I ran with the filter type breather on, like this.



Then I switched to this method using the ports on the bottom of the air cleaner

 

i think you've got a hose off.

locate the PCV valve in the top of one valve cover. some years its on passenger side and some years are on driver side. it should have a hose connected to the intake, which is sucking vacuum. i'm sure you already know this but the pcv has a rattley check valve thing that goes into the valve cover.

then in the valve cover on the opposite side of the engine is a simple elbow, connected to the INSIDE of the airfilter. its purpose is to pipe FILTERED air into one side of the engine, where its drawn out the other side by the pcv, and then dumped into the intake for burning.

if your round air filter has no port for the vent hose, then replace the elbow and hose with a simple little valve cover filter. its important that the pcv suck in FILTERED fresh air.

 

Alright makes sense! Thanks dhvaughan. If you look in the first picture that is how I had it, but for some reason it was making it hard to start. It was almost as if the round filter was creating a stronger vacuum then the stock airbox and sucking oil in from the PCV because when I look down in the intake manifold i saw oil saturated on the wall of the manifold where the PCV hose inlet port is. No plenum leak though, did the hughes fix back in November.

 

sorry, i can't tell from the pics what is what.

which one of those is your PCV and is it connected directly to the side of the manifold? it should pull a larger vacuum than the filter air hose inside the air cleaner. for simplicity, its actually a lot easier to put a breather on the fresh air side and lose all hoses to the air filter, and just cap off their ports.

just a thought - make sure you have a pcv (with check valve on one side) and two way vent on the other. make sure you don't mistakenly have 2 pcvs with their check valves fighting each other.

hook it up according to this general diagram. your oily crankcase vapors need to vent into the manifold.

 

Yes sir that is how I had it originally but with just the breather on the fresh air side. On the 97 the PCV valve is on he passenger side valve cover, and plugs directly into the side of the manifold. I just hooked the 14x3 back up but this time I have the fresh air breather sucking air from the air cleaner this time.

Thanks again for the help dhvaughan! The diagram is a great picture of how the circuit works.

 

how come you dont have a pcv valve?

 

I do have a PCV valve, I just had it off for a while because I was experimenting, trying to get rid of the smell.

 

i have the same oil fume smell problem (some people tell me it's a problem, i like the smell, reminds me of the old grain trucks we used to run before upgrading to big rigs)

when i did the plenum fix i replaced my PCV valve (the old one didn't rattle)

i have yet to drive it (tomorrow) hoping that fixed my oil smell problem