I know, not a Toyota question but something I found interesting: A guy I work with has a jeep Cherokee with the 4.7 V8 in it that is 5-7 years old. Apparently the other day he was freaking that he couldnt come to work because his headgasket was blown. He said he pulled his oil cap off and it was all milky. But he then called his Uncle who was a Mopar mechanic and he told him that this is normal and that there is some valve that goes between the coolant and oil that lets a little bit seep through. He checked his oil dipstick though and it's all oil and the coolant doesn't have any oil in it, it's just the cap that is coated with an oil/coolant mix and the threads of the cap and slightly below. He says his uncle also says that they some sort of baffle on newer Jeeps so you can't see this so it doesn't alarm poeple or something like that? He said he's not blowing white smoke, the thing runs fine, and it's normal. Interestingly enough, when he pulled the cap off, there was a few small drips of water/coolant that fell out when he showed it to me.

Any thoughts or info for those who might know more than me? This kind of crap can't be good for your engine. Is it some kind of weird Chrysler thing?

 

it is normal on early 3.7L (a 4.7 minus 2 cylinders) and early 4.7L. like his friend said their are baffles in place on later builds to prevent the vapor sludge build up (on the cap)! it does not effect reliability. most people just wipe it away with a towel and go on partying! it is a fairly new engine (debuted in 2000) so not many have high mileage yet but 3 have made it into the 200,000 mile club with no problem! link below! mike

http://www.allpar.com/old/club/searc....7&type=engine

 

I have seen water residue inside the oil cap without there being a blown head gasket. The reason it was there, was because the little old lady that drove this vehicle, didn't drive it often and it would build up condensation inside the motor. You'll see it more frequently in smaller motors like lawn mowers and other little equipment for the same reason. I just recommended to these people to do oil changes more often to compensate for the water being in it. As far as suggestions, I don't know. I don't know if this is the reason that his is doing this or not? I just thought I'd pass the info along.

 

I suggest changing the PVC valve. Its job is to burn off moisture in the crankcase and vapors caused by blowby and heat/cool cycles.