Was about to change the plugs on my 4.2L engine when I discovered an oil film on all the old ones and began investigating. A puddle of oil about an eighth of an inch deep had accumulated in the throttle body and manifold. Took off the throttle vane section of the body and front access cover on the manifold and cleaned out the oil/varnish as best I could. With the help of the posts on the Forum and discussion with a technician, PCV damper valve was identified as the culprit, so replaced with a new one. After several weeks, noticed oil still settling in the body, so took off the right cam cover and inserted additional steel mesh in the breather slots at the top. Oil now down to only a thin film in the throttle body ell. Hoping that all the "Techron" ads are true, and it will clean up the valves. Big plus of this episode was the restoration of engine performance and gas mileage to new-car levels - 10% improvement.


Should checking/replacing the PCV be part of a preventive maintenance guideline offered somewhere? This is surely one of those "ounce of prevention" situations, considering the mess and performance downgrade it creates and that a new PCV is $45.00 (did not try to clean the old one, as did not feel able to assess if successful). Looking at the dealer 10,000-mile maintenance checks, I don't see such an inspection on the list. I wish I had discovered the situation sooner, of course, but, looking back, only indication was slight decline in performance and mileage.


Anything I missed in dealing with this? Or did misguidedly? How have other members dealt with excess oil being drawn through the PCV?

 

I would change the oil from 5w-30 to 10w-30 and see what takes place.

 

An air filter, that isn't flowing well, like an over oiled K&N, or a dirty air filter will cause the engine to pull oil up into the intake, because it is scavenging air through it's PCV and other parts of the ventilation system. Diesels are known for this, once they get some wear. A wet air filter will cause the same thing.......Just my 2 cents.....Be cool.....Mike

 

Yes it could but you would have codes and none have been suggested or posted.

 

Have always used 10w-30, as not worried about the cold viscosity (San Diego) and always thought that the higher weight oil coats/holds the metal better. Would 20w-40 be too much?

 

I have a near-new paper filter installed. Does the left-hand-side partial ventilation get clogged and could it be contributing to the problem?

 

No codes were shown. Only indications were the decline in performance and a slow/ partial-misfire start once in a while ( if it sat for several days).

 

Correct me if I'm wrong, but it was my understanding that these cars don't have a PCV valve, but instead have Part Load and Full Load Breather Hoses that do pretty much the same job.

Is there a PCV valve on this car? If so, where is it located and what is the part number? I find it odd that you have a price on them.

 

I don't think any of the 4.0 have them, but the 4.2 does,

 

Ah, I see. I'm guessing the Valve system is better engineered?

 

Don't know if better engineered - I did not have this problem with the 4.0L car I owned previously - but more conventional: air taken in at the left side cam cover and coming out on the right through the PCV, I believe. Part number is AJ87773.