Cherokee America - My Jeep is Blowing Oil onto the Air Filter!!

Nov. 01, 2005 By ORC STAFF
BUY JEEP PARTS: 4.0L Valve cover | 4.0L Crankcase ventilation tube
CCV Picture
  • Part # 4762592 is circled in red
  • Part # 53004838 is circled in green
  • Part # 53004868 is circled in blue
  • Mopar Part # 4762592 - $17.50  This only includes the rear grommet and the tube going to the intake manifold.
  • Mopar Part # 53004838 - $33.55   This is the left half of the vaccum hose harness assembly which includes the front breather hose.
  • Mopar Part # 53004868 - $24.00   This is the right half of the vaccum hose harness assembly which hooks up to the air cleaner.
I think everybody that owns a 4.0L Jeep engine has had this problem or is going to have this happen to them sooner or later. No you don't need to rebuild your engine and yes it is blow-by from the piston rings but its just normal blow-by that's out of control.

The valve cover on the 4.0L has two breathers on it, the front one is just that a breather but the rear one is a PCV {positive crankcase ventilation} valve, breather, I say breather because the PCV valve is built into the valve cover. And the only way to replace it is to get a new valve cover, but this is probably not your case. What happens is the rear breather is made of rubber and after time it hardens and tends to close up and or plug up with soot. In tern this puts all the engines crankcase pressure threw the front breather and causes it to carry oil through it to the air filter.

Fortunately Chrysler has addressed this and made it a simple and inexpensive fix. All that you have to do is go to your friendly Jeep dealer and buy part #4762592 and install it on your rig. It will come with both the front & rear breathers and all the rest of the vacuum lines on your engine.I know what your thinking, I'll just go and buy the rear grommet. Sorry Chrysler doesn't offer it, and for a very good reason too. Fuel injected engines such as the 4.0L don't run good at all with vacuum leaks so by selling the kit as they do Jeep is taking care of other potential problems with one package. I would recommend changing this at regular tune up intervals of 30K mi. but no more than 50K mi. MAX.

If this doesn't take care of your problem then you need to replace your valve cover. Because somebody didn't change the engine oil every 3K mi. or less and has gummed up the PCV valve. Buy the way not changing the oil regularly is the leading cause of engine failure in the Jeep 4.0L.

Models Affected: 1987-1990 Jeep Cherokee/Comanche

Customer complaints of an engine oil leak or oil consumption may be caused by one or more of the following conditions:

  • A loose fit between the crankcase ventilation {CCV} plastic tube and the molded elbow at the intake manifold.
  • Oil accumulating and leaking from the air cleaner assembly.
  • Air filter saturated with oil.
  • Blocked or restricted CCV grommet at the rear of the rocker cover. The grommet orifice should be 2.6mm in diameter.
  • Sludge formation on the valve train components and the inside of the rocker cover.

If one or more of the above conditions is experienced, proceed with the following repair which involves installation of a replacement crankcase ventilation tube.

First remove the original CCV tube, elbow and grommet in the rocker cover. If you determine that oil sludge has accumulated inside the rocker cover, clean away the sludge buildup, being sure to inspect and clean the oil return passages in the cylinder head. Install cover on the engine. Next, clean any oil from the air cleaner housing if necessary. Then install the new CCV package, P/N 4762592, in place of the original CCV tube, elbow and grommet.

Followup:

If you have replaced the CCV gromet, you have a strong vacuum, and your engine is still blowing oil, then the next step is to remove the valve cover and clean the sludge or carbon accumulation off the inside.

Here is an article explaning how to do this.

Update:

Thanks to Roy Avery for this update!
I've updated the picture to reflect his comments.



In this article it gives a Mopar part # of 4762592.  The article leads you to believe that the part # includes the harness assy for the front breather as well.  I have the part #'s and prices for the vaccum hoses. 

  • Mopar Part # 4762592    I paid $17.50  This only includes the rear grommet and the tube going to the intake manifold.
  • Mopar Part # 53004838  I paid $33.55   This is the left half of the vaccum hose harness assembly which includes the front breather hose.
  • Mopar Part # 53004868  I paid $24.00   This is the right half of the vaccum hose harness assembly which hooks up to the air cleaner.

 

  • Part # 4762592 is circled in red
  • Part # 53004838 is circled in green
  • Part # 53004868 is circled in blue

I think that if the article were changed to show the individual parts with numbers and prices, it would really help out.  Luckily I had a real friendly parts guy behind the counter at the Jeep dealership.

Roy Avery
roymtbkr@rocketmail.com

Off-Road.com Newsletter
Join our Weekly Newsletter to get the latest off-road news, reviews, events, and alerts!