Blow-By problems

That tube that goes from the valve cover to the airbox pumped oil into my engine, when I took my TB off I had all kinds of blackish crap all over, It looks like old oil. Is this normal? is the 4.0 I6 supposed to burn some oil? also it is leaking like a B**** there is oi all over the under side of my engine but, I can't pin point where it is comming from...

I'm no expert on this, but it sounds like a bad PCV valve...

That tube that goes from the valve cover to the airbox pumped oil into my engine, when I took my TB off I had all kinds of blackish crap all over, It looks like old oil. Is this normal? is the 4.0 I6 supposed to burn some oil? also it is leaking like a B**** there is oi all over the under side of my engine but, I can't pin point where it is comming from...

Unless you cleaned your TB in the last two years it's normal to have black crap there. That why we all clean it. Not it is not normal for our wonderful engines to burn oil. I would be that it is leaking from the valve cover gasket or the rear main seal. The way to know for sure is to steam clean your engine and then keep a close look. If you find that it's the valve cover gasket you may want to give you valve cover bolts an 1/8 of turn or till it tight.

Replace your pcv valve and then see if oil is still getting into your air cleaner assembly through the breather if so your rings aren't too good. So you may throw some marvel mystery oil into your engine and run that for 3k and then put in z-max or slick 50 something like that.

most if not all modern 4.0 do not have pvc valves, as for your oil leaks, clean motor than keep an eye starting from the top to the bottom. Along with oil additives try going with a thicker oil, 10w40..ect do not go to thick during colder months. from my experience as a service tech in the past, blow by is very very common in these motors, as is dirty throttle body, very simple to clean! :2cents:

It isn't leaking from the valve cover, that got a new gasket probably about 5000 miles ago.

Is the oil on the front of the engine as well as the back?

As the others have suggested, a good degreasing is the first step. Then check often. Look particularly around the front and rear crank seal areas.

I had a rear seal leak that completely covered the bell housing and tranny.

It isn't leaking from the valve cover, that got a new gasket probably about 5000 miles ago.


The line on the front of valve cover ,pulls air into engine. The one in the rear of valve cover has a small orfice or opening in it. It has vacuum coming from intake manifold and draws the gas vapors back into engine to reburn. Check the line on rear of cover be sure its clean from cover to intake manifold. Remove the line from fitting that goes into manifold make sure fitting isn't plugged up if so clean fitting. That line has vacuum all the time the jeep is running. Make sure it has vacuum. Dale [email protected]

The line on the front of valve cover ,pulls air into engine. The one in the rear of valve cover has a small orfice or opening in it. It has vacuum coming from intake manifold and draws the gas vapors back into engine to reburn. Check the line on rear of cover be sure its clean from cover to intake manifold. Remove the line from fitting that goes into manifold make sure fitting isn't plugged up if so clean fitting. That line has vacuum all the time the jeep is running. Make sure it has vacuum. Dale [email protected]

Will do thanks for the info...

Is the oil on the front of the engine as well as the back?
As the others have suggested, a good degreasing is the first step. Then check often. Look particularly around the front and rear crank seal areas.
I had a rear seal leak that completely covered the bell housing and tranny.

Ya but, not as much as the rear portion of the engine, I hope it isn't serious like my mom's stratus, She has a 97 stratus with 88000 miles, we were told it needed a head gasket since it leaked oil like hell, when they were installing the gasket kit they came across the real problem, a manufacturing defect in the block where it is literally pumping oil out, Chrysler won't cover the repair. It is not our doing why should we have to pay for an engine replacement? It's chrysler's fault. We WILL NEVER buy a chrysler product again, except for me, I will always drive a jeep, too bad they quit making the xj I hope I won't have to start driving a ford, ford is a bad thing lol

Check previous threads I had the same problem oil was getting pushed through the fresh air vent into the air cleaner. I removed the tube connecting it and just put on a k and n breather filter. It still leaked oil so i took off the valve cover and there was serious carbon bulid up on the inside. Cleaned it all out and no problems since its been about 2 months. The 4.0 engine i guess is known for this problem.

I'll have to check out that valve cover, to see if there is any carbon build up, Is there any way to take the valve cover off without ruining the gasket? I just put it on about 5000 miles ago. The only automotive place around here has to order the gasket in. I live in the middle of nowhere I have about a half an our drive to autozone. It is nice liveing out here though, many many places to go off road.

if it is a good rubber type gasket you are good, but if you are not 100% sure than better have a new gasket om hand just in case

I it is a cork gasket that I got from Autozone. I is glued in with that Black RTV High temp silicone. I hate to buy another gasket but, if I have to, I will/

Since it's cork, I'd have a replacement on hand just in case. If you're able to reuse the old gasket, you can always return the new one or keep as a future spare.

I could probably just get another gasket and if I don;t need it is is only a few bucks anyway so I could probably just use it as a spare.

The PCV is not used on most of the 4.0 L engines. Instead it is called CCV - Closed Crankcase Ventilation. At the rear of the valve cover, on top, there is what appears to be a vacuum line. This line is inserted into a small hole, called the orifice. It uses vacuum from the intake manifold to suck crankcase fumes from the block and reburn them.

This orifice gets plugged with age. It is, I believe, 2.8 mm in diameter. When it gets plugged, blowby in the engine can not be ventilated to the air intake. Instead it takes the other route, which is through the hose on the front of the valve cover. And that is wrong! The result is the fumes are now blown back that hose and into the air filter. That hose is supposed to draw fresh air INTO the engine, not allow fumes and residue out!

The second thing that happens is the pressure, unable to escape through its normal route, now blows oil out the rear main seal of the engine. That is why this simply little 2.8 mm orifice causes what appears to be a major oil leak. And what can turn into damaged seals.

The cure: Remove the orifice from the valve cover. It pops out, though not easily. With it out, drill it open with the proper drill bit - should just fit into the 2.8 mm hole. The hole will be plugged, of course, with some really cruddy stuff, so be sure to remove the orifice from the valve cover before drilling. Once the hole is clear, put the orifice back. Insert the vacuum line into the orifice. Don't overdrill the hole or the vacuum line will not stay in there! Actually I just used a small screwdriver and scraped all the junk out. It just has to be a clear hole, no blockage.

Problem cured. Ten minutes. No more corrupted air filters with blow-back fumes and junk coming into the air filter, and no more rear engine oil seal leaks.

Ed

I talked with a friend last night abou tit and he showed me what he did on his jeep, what he did was get this rubber stopper like thing with a hole in the middle, took that l shaped piece of plastic out and installed the stopper in the hole, hre then bent a piece of brass tubing in the shape of an "L" and put that in the stopper, the tubes were then attached to the brass tubing... Is that a good idea to do on mine??

Are you making a still?

Huh?? a still? I'm not following... lol

Ed is right about the ccv... had same problems... I do believe that the rear main seal for the 95 is the same as my 92 which would be a 2 piece seal (13 or 14 bucks at autozone, and an oil pan gasket (18 or 19 bucks). I have been told that the seal is able to be changed by pulling the oil pan, then take off the last main bearing cap... the seal is actually like an inlay and the secon piece is over the crank. I have same prob there also... I run Castrol 10w40 high mileage and a bottle of lucas oil stabilizer (they are not a very cheap remedy, but it is my current remedy and it actually works rather well. I am going to change mine as soon as it gets warm again) Good luck

so, I don;t have to pull the transmission? I was told the only way to replace that seal was to pull the transmission...

what exactlt is the difference between 10W30 5W30 10W40 ect...

My parts guide show it as a 2 piece seal for the '94-'96 models.
"4778 126 1 SEAL PACKAGE, Crankshaft"

http://jeepin.com/features/rearmain/index.asp is a good reference for doing the job yourself. Since the pan gasket is generally also cork, get 2 in case you trash one. Better yet, find a rubber, 1 piece gasket.

As for the oil weights, these represent the oil viscosity "ranges" for multiwieght oils. These are modifed oils that allow them to retain their low weight properties (flow better when cold) yet not thin out too much when hot. The W stands for "winter".

So a 5W30 oil flows like a 5 weight oil when cold allowing it to circulate in your engine easlily, but still works like a 30 weight once your engine is up to temp. This helps ensure you retain proper oil pressure and lubrication.

If you have a 95 xj, then no, you don't pull the tranny, just the oil pan and last main bearing cap. The seal design was actually changed in either 91 or 92 because my 92 is 2 pieces. it was one of the changes that chrysler brought after buying from am general

My '88 has a 2 piece seal.

This is a problem on some jeeps first remove all the vaccum lines and clean with B-12. Then remove your valve cover and clean it with the same, install a new valve cover gasket. Clean your intake will also help when these are old the have a problem with yetting stoped up and not breathing properly.

Thanks for the pointer... Used some seafoam and got it cleaned out. No more problems now. didn't have to take the valve cover off thankfully.

:banghead:
OK I took my jeep to PEP boys who performaed all sorts of work that did not need to be done. A few months earlier they put a new gasket on my valve cover... no big deal but I noticed that I had an issue with oild dripping out of the transmission plate whick looked to be near the rear main seal. It happened often expecailly when i was on the highway, a long story short i had everything replaced even the rear main seal and it was still leaking. I made Pep boys give me a full refund. I read and read about the blow-by issue. I decided to give it a try. Even though I had no oil in my air filter it seamed as if I had unusualy high pressure. Well i ordered the rear and front valve cover Elbow peices and hose assembly. When I took off the rear one i looked at the peice and I noticed something strange on the bottom inside on the valve it was open but the new piece seemed to have a cap over it with a little hole. I quickley took the one in the front off and much to my suprise the one with the little hole was in front(Not correct). I then proceded to swap them and now i leak no oil. I have no blow by. I called the dealer and spoke to the service forman who proceded to laugh and say well I know why your leaking oil!!!! So just as a note the cap with the little hole in the bottom goes in the back of the valve cover and the one that looks completly open goes in the front. If you get them switch you will build pressure in the crankcase and the oil will go out of the rear main or anywhere where it can do to the high pressure. Also if you get your valve cover gasket redone by someone else check that they fixed it properly.:screwy:

Hi-Ya Sandrobber... Welcome to AF. That's an interesting story there, glad you got your $ back and solved your problem.

One minor thing though, if you could, try not digging up threads that are any more than a couple months old. Don't get me wrong, that's great info you gave there to a potentially serious problem, but the last entry before yours was like 1 1/2 years ago mate. LOL, WOW!