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And I found this:
In the oil filler tube. It's not on the dipstick or anything, Just in the tube. Anybody know what it is? And also, The oil was very old.... It was pitch-black. The car is a 99 Jeep Grand Cherokee Limited with the 4.7l V8, It has 136k on it.
 

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Welcome to Allpar. That is basically mayonnaise, like when water and oil mix like in a salad dressing. I wouldn't be too alarmed by it this cold time of year as a lot of condensation builds up inside the upper engine and short trip driving makes it worse. Just make sure that you perform regular oil changes, more-so in winter and that the PCV is working OK.
Beware some shops that try to sell you a head gasket job if this is the only symptom. The 3.7L and 4.7L engines both had tall plastic oil filler pipes with the PCV inside them at the front of the engine that ran cold and allowed condensation to form. You probably won't see this in the summer. Some pipes had a removable baffle inside them to lessen this build-up.
 

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I've had that on the oil filler cap (although not quite that big a dab), on a perfectly healthy engine in winter, that was driven on short trips. Longer trips and warmer weather, and a functioning PCV system will clear that out.
 

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Ok, Thanks. I diden't think it was a head-gasket because the oil, Although old, Was fine and there was no oil in the radiator. I do do alot of short trip driving, Everything is located within a mile from my house, So I generally drive just a few miles every-other day. This is probably a dumb question, How would I check to see if the PCV system is working correctly? I just had to change the MAP sensor last month, Everything looks original on the engine. And thanks for te welcome and your replys!
 

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I suggest that you buy a can of Amsoil engine cleaner to rid the thing of the black crud. Just dump the stuff into the oil, run the engine at idle, do not drive the car . Empty the oil, change the filter, and add new oil. The stuff is absolutely amazing in how well it cleans the engine interior.
 

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I don't know where it is on that engine, but to test the PCV valve, just pull it out and put your thumb over the valve cover end with the engine running. If you feel strong suction, it's working. Shut the engine off and shake the valve, and you should hear it rattle.
 

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Discussion Starter #7
Ok, Thanks!
 

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Not all modern PCV valves are meant to rattle when shaken. Some have a light return spring inside to hold them closed when the engine is off. Yours should be mounted in the side of the oil filler tube and a twist should unlock it.
If you do replace the PCV, only use an OEM part like Mopar as the vacuum calibration differences between aftermarket brands can make sludge build-up worse if too little or give a rough idle if too much, etc.
The vacuum hose for the PCV probably fails more than the PCV valve itself. After a few years of underhood engine heat and being soaked with engine oil and blowby products, the rubber will soften and rot. Many will suck flat like a straw, especially at a bend and reduce PCV flow that way. Some are formed hoses and straight hose won't work without kinking. You want the best possible vacuum flow here.
Good engine oil is very important this time of year as moisture and contaminant build-up can damage an engine.
In your case, with old, dirty engine oil and short trip winter driving this mayonnaise is probably normal and not to be overly concerned about.
 

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Ok, Thanks ImperialCrown. I used a Mopar oil filter and Quaker State High Mileage oil when I changed it. The power steering will kinda whine sometimes and it will get hard to turn when I first start the Jeep, But not all the time, So I bought some Lucas power steering restorer, But then I read on another site that to ONLY use Mopar stuff, And NOT to use any other additives.... SO, Would it be Ok to use the Lucas stuff or just completely flush the system and use the Mopar power steering fluid? I have not used the Lucas stuff yet.
 

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And I found this:
In the oil filler tube. It's not on the dipstick or anything, Just in the tube. Anybody know what it is? And also, The oil was very old.... It was pitch-black. The car is a 99 Jeep Grand Cherokee Limited with the 4.7l V8, It has 136k on it.

Next oil change add a bottle of MOTOR FLUSH and run it for 5 minutes. Change filter and oil and you will amazed at how clean the next oil change will be. Every passage will be cleaned and it doesn't hurt the engine. I have been using this product for three decades and every car I own run like new and never burns oil.
 

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I have the 3.7L V6, its the 4.7L with 2 cylinders lobbed off. I get the same in the oil filler tube. Your PCV could be perfectly fine. Look at the oil filler tube, no air is circulating inside that, likely why you get the emulsified oil there. Same with the oil filler caps on a lot of engines, its the one spot the air doesn't circulate as well, so it collects there.
 
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I have the 3.7L V6, its the 4.7L with 2 cylinders lobbed off. I get the same in the oil filler tube. Your PCV could be perfectly fine. Look at the oil filler tube, no air is circulating inside that, likely why you get the emulsified oil there. Same with the oil filler caps on a lot of engines, its the one spot the air doesn't circulate as well, so it collects there.
The foam is usually associated with moisture. It's caused by condensation, or actual water intrusion, so the air circulation theory is plausible.
 
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