Roggesound Posted February 15, 2013 Share Posted February 15, 2013 I'm sure there's something about this in the forums somewhere, but I haven't been able to find it. My 88 comanche has had foamy wet oil sludge pushing out of the PCV into the air box on top of the air filter. I know there's water in there, because when it's cold, it freezes. The same stuff seems to push up the dipstick tube after driving long distances, because I see it on the dipstick when I check the oil. So I thought this was just a problem with my Jeep, but I went to look at another guy's 88 Comanche today, and his had the exact same thing. His oily foam was a bit cleaner than mine, but it was there, dripping onto the air filter just like mine does. My question is, what is causing this, and is there anything I can do to fix it? Link to comment Share on other sites More sharing options...
87Chief Posted February 16, 2013 Share Posted February 16, 2013 I believe it is the pcv tube on top of the valve cover.. or ccv depending on the year.. Someone might jump in though to correct me. Link to comment Share on other sites More sharing options...
87manche1 Posted February 16, 2013 Share Posted February 16, 2013 The vaccum side of it ( tube coming from valve cover to manifold) Is probably clogged at valve cover has four small holes that get built up causing the fumes to run down the filter tube that carries vapor that condenses will sitting Link to comment Share on other sites More sharing options...
Eagle Posted February 16, 2013 Share Posted February 16, 2013 A 4.0L doesn't have a PCV, and the tube that opens into the air cleaner box isn't the suction line for the CCV system anyway, it's supposed to be the inlet for air to go INTO the valve cover. The suction tube is the small plastic line off the back end of the valve cover. What happens is that it gets clogged and there's no suction, so no way to evacuate the oily fumes from the crankcase. Plus as the engines get older and more worn, there's more blowby at the rings, so the crankcase becomes pressurized rather than being a partial vacuum. The oily fumes can't go where they're supposed to go, so the system works in reverse and pushes the fumes back out through the inlet tube into the air box. The water you see mixed in is condensation from cold weather operation. Link to comment Share on other sites More sharing options...
Roggesound Posted February 18, 2013 Author Share Posted February 18, 2013 Should I remove the PCV? It had one when I bought it, and I replaced it, but I figured it didn't come with one, because the parts store couldn't look it up, I had to show them the old one. Would it work better if I just jammed the tube in the hole in the valve cover? What I'd like most is to keep the oil from hitting the air filter, which makes it less filtery. It's interesting to think that this is just condensation, but I guess that makes some sense, since I don't see the same stuff in the valve cover. Is it also condensation inside the dipstick tube? Link to comment Share on other sites More sharing options...
cruiser54 Posted February 18, 2013 Share Posted February 18, 2013 Should I remove the PCV? It had one when I bought it, and I replaced it, but I figured it didn't come with one, because the parts store couldn't look it up, I had to show them the old one. Would it work better if I just jammed the tube in the hole in the valve cover? What I'd like most is to keep the oil from hitting the air filter, which makes it less filtery. It's interesting to think that this is just condensation, but I guess that makes some sense, since I don't see the same stuff in the valve cover. Is it also condensation inside the dipstick tube? Put new vacuum harnesses on it. If you're real ambitious you can do a mod to the valve cover also. Renix Vacuum Harnesses The vacuum harness that attaches to the front of the valve cover and includes the grommet/fitting, and is called the front harness, is Napa part number BK 715-1367 http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=BK_7151367_0269070623 The vacuum harness that is closest to the air cleaner, EGR etc, and is called the rear harness, is Napa part number BK-715-1366. http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=BK_7151366_0269070622 The tube from the rear of the valve cover to the intake manifold is part number 715-1365. http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=BK_7151365_0066877355 Revised 09-11-2012 Cruiser’s Valve Cover Mod Most early and even later Renix 4.0s could be bothered by excessive oil in the air cleaner box. A fix from my old days as Service Manager at a Jeep dealership follows. Information was provided to me from a buddy at JeepTech during those days. I don’t believe it ever came out in a Technical Service Bulletin. Remove the valve cover and turn it over. Next, remove the fluted tubes that are now facing you by removing three screws on each. Chop 1 inch off each of them. Then, about a half inch up from the area where you just sawed them off, drill a half inch hole in the tubes so the holes will face the rear of the valve cover. Clean and de-burr/sand all rough edges nicely, clean with solvent, and reinstall. Don’t be concerned about the chintzy gaskets that will probably crumble into oblivion when you remove the fluted tubes. They can go back together without gaskets. Link to comment Share on other sites More sharing options...
Roggesound Posted February 18, 2013 Author Share Posted February 18, 2013 NOE 7151365, NOE 7151366, NOE 7151367 are the part numbers I'm finding on the napa site, and I'm just putting them here for future reference. I will definitely give that valve cover mod a shot when the weather warms up a bit. Thanks very much! Link to comment Share on other sites More sharing options...
cruiser54 Posted February 18, 2013 Share Posted February 18, 2013 NOE 7151365, NOE 7151366, NOE 7151367 are the part numbers I'm finding on the napa site, and I'm just putting them here for future reference. I will definitely give that valve cover mod a shot when the weather warms up a bit. Thanks very much! I've got a photo of the flutes cut off but I can't post it. Link to comment Share on other sites More sharing options...
88whitemanche Posted February 19, 2013 Share Posted February 19, 2013 Do you have those same part numbers for the four cylinders? I need to replace mine but only to find those 6 cylinder ones Link to comment Share on other sites More sharing options...
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