oil in air cleaner???

[puddlejumper]

Hello Jeep Folks
I'm wondering if you can help me out. I have an '86 GW w/ a 360. I can't stop oil from coming up through the oil filler tube and into my air cleaner housing. I'll actually have standing oil in the bottom of the housing just 100 miles after cleaning it. The element is in the plastic filler tube cap. Oil pressure seems fine, just replaced PVC and checked vaccum lines, no black smoke while driving or climbing hills. Any ideas on what is causing it or how to stop it?

[kreb]

bad rings were the death song on my last motor. if the rings are bad then oil will get by and into your breather. what is your oil pressure like? check for oil on your plugs

but don't quote me on the above, i was just giving a possible cause. it could still be somewhere in your pcv system. make sure your valve in positioned correctly

benjamin

[Babalou]

I had the very same problem but only after replacing my stock intake manifold and neglecting to replace the baffle and valley pan gasket. My immediate fix for the problem was to remove the hose from the air filter housing to the oil filler cap. The solution to the problem (for me) was to install a valley pan gasket. So far I have had no further problems with oil in the air filter housing.
Good luck

[carrotman]

Welcome. I'm not familiar with an 86, and it may have different crankcase breathing, but according to the 76 TSM, if blowby exceedes the flow capacity of the PCV valve, airflow in the system will reverse. Crankcase vapors (oil) will come out the oil filler cap into the air cleaner. There are two PCV valves. The silver one is for sixes and black one is for V8's. If you get the silver one on your V8, it will suck oil. Try a black one first.

[Don S]

..
Puddlejumper

Welcome to the group of us demented FSJ wheelers.

I would like to add a little to Carrotmans post

OIL IN THE AIR-CLEANER
According to the official 1981 AMC Technical Service Manual, "when crankcase pressure (blow-by) exceeds the flow capacity of the PCV valve/hose, airflow in the system will reverse".
... Crankcase vapors (with fine oil droplets) will come out the oil filler cap (V-8s)into the air cleaner.
OVERVIEW
... The crankcase ventilation system works on a balance of crankcase pressure and manifold vacuum. At some point ‘blow-by’ will be able to over power the PCV system. During times of long hard acceleration manifold vacuum falls to nearly zero and even a fairly good engine will put the airflow in the system in reverse.
A FEW SOLUTIONS
A. Check for leaks in the vacuum system of any kind.
B. Check PCV valve operation.
C. Check PCV hoses for proper installation, cracks, leaks and/or obstructions.
D. Slightly larger PCV valve and hose.
E. In the six cylinder engines a redesign of baffles and filters in the valve cover for both PCV and breather hoses.
F. Use less throttle during acceleration?

Good Luck.. http://www.datsunnissandrivers.com/forum/images/smiles/069.gif.. Don S..

[Wagoneer622]

Welcome to the board, awesome a fellow New Jersian. You will like this place, it is a vast network of information and there are lots of good people here.

[puddlejumper]

Thanks for your input and welcome to the forum, everyone. After learning the term "blow by" from this discussion, I found another excellent discussion on the subject from a Friday forum thread. That, with the answers I got today, has given me a lot of food for thought and some places to begin to look for the solution.

[J10man]

You need to talk to Jeepfreak my son. I have the same problem and he turned me on to some good info. The 360 runs the passenger exhaust through the intake to warm the engine quickly, when the intake seal breaks the engine is pressurized from exhaust gases. Here is a copy of his reply, he deserves all the credit: J10man... Sounds to me like the exhaust crossover in the intake didn't get sealed well and you are getting a crankcase full of exhaust gases. I had the same exact problem with a fresh 360 and after kicking around ideas Bob Barry suggested looking at the exhaust crossover and sure enough that was the problem. These seem to be bad about sealing. I used a little copper silicone around the passages for the crossover and problem solved. I then tried this on a Wag I had with 125K and it fixed it's oil in the breather problem as well. The metal crush gasket just doesn't seem to seal all that well. 89er, have you done a compression test. If so did you notice any leak down from the cylinders? If all of that checks out you might look at a new intake gasket and when you do this it will allow you to clean the PCV passage as well.

[jfiscus]

I may be wrong, but I believe that the original post describes a different problem then most of the answers here refer to.

I have this same problem with my oil filler tube. I beleive there is some type of seal that is missing around the cap. during periods of heavy driving the oil manages to work its way out of the filler tube and gets onto the engine, hood underside, and air filter on the carb.

I went to the parts store and got an oil filler tube seal and it didn't fit the cap. (the cap also appears to have some sort of breathing holes on the underside of it that the oil may be escaping through. Is this bad?

[J10man]

I believe once you get rid of the pressure in the crank case it won't blow it out the filler tube. I tried sealing off my breather tube and the motor just blew the pressure out the dipstick tube. There shouldn't be so much pressure in the motor that it blows it out I don't think.

[puddlejumper]

Thanks for the heads up, J10. That makes a lot sense; obviously something is pressurizing the heck out of the crankcase, and that would do it. It may explain oil leaks around seals as well. I took mine for an inspection today, and the mechanic said that he thought it was blocked air passages in the engine. He told me to put a quart of kerosene and let it run for 10 minutes just before I next change the oil. The guy I bought the wagoneer from last year told me that the engine had recently been rebuilt. I know the oil pressure is pretty good, so I'll buy the exhaust gas over the rings diagnose. Thanks everyone.

[letank]

Puddlejumper said :obviously something is pressurizing the heck out of the crankcase.

under the PCV valve or the the PCV manifold connector and different years different system.

There is a baffle (not the valley pan) and this baffle: a sheet metal with slotted holes, can get plugged up with blow by..... one solution is to ram a screwdriver in there... to clear the slots of the junk... but then what happen to the pieces of junk, or tar?

Michel

[andy d]

hmmn, i wonder if this is what happened to the engine in my new 88.it had horrendous blowby into the air cleaner. messing around with it, i blew out the back of the intake manifold gasket. figured the engine was toast and swapped it out

[J10man]

My new engine sprayed oil mist out of the filler tube at first. When I got tired of that I put a solid cap on. BAD idea, I immediately lost my valve cover seals, threw oil out the dipstick, and even out the intake. LOTS of pressure. From what I understand, many 360s end up with the intake leaking this way. Keep in mind that this is a brand new motor, it has no bad rings and there are no blocks in the motor or intake. JeepFreak says the problem is a lot more frequent with aluminum intakes which I am running.

[puddlejumper]

Well, when it rains (or snows as the case currently is), it pours. I had to open the air cleaner today to sort a stuck choke issue - noticed a white milk like deposit inside. There goes my Saturday - hope it is just the head gasket. Oh Well, at least this gives me an opportunity look in depth at the exhaust crossover seal.

[JeepFreak]

I wouldn't pay to much attention to the milky oil in the breather. As a motor warms up in the winter you will get some condensation that can mix with the spray "mist" from the filler tube. If you don't have water in the crankcase oil or oil in the coolant then don't go tearing your heads off. I suggested to J10man that his crossover could be leaking as his situation was exactly the same as mine...New motor with lots of crankcase pressure. I have now had the crossover leak on two AMC V8's and both had aluminum intakes. If it was me I would get back to basics with a compression test and leak down test, then go from there. What's the history on your motor (miles, rebuilt)? Are you running a stock intake or aluminum? This info in addition to your compression test will tell us allot.

[Nobby]

Hmm just a thought Recently rebuilt motors you say are possibly experiencing pressurised crankcase issues.

Well blowby could exist with rebuilts because the engine has not achieved good ringseat post build. Rebuild does not garauntee ring seat. How its broken in/treated after does however as well of how you rebuilt it of course.

Not saying this is the problem just an observation on the posts. Would be intrigued to hear what results are from a compression test.
Like the crossover leakage idea also you'd think you'd be possibly able to sniff exhaust through the filler if that was the case

[puddlejumper]

Jeepfreak - I can't think you enough for mentioning the condensation which made me take a harder look at it. Everytime in the past that I have seen milky oil, it was baaaad news. You are right; I just changed it and it had no oil in it. None was in the water either. I spoke to a mechanic who said, like you, condensation would do it in the cold weather. He recommended changing the thermostat from 180 to 195 to eliminate the condensation. I did that today - sure beats head gasket.

Dodged that bullet. Again, thanks for the input.