The joys of familiarizing oneself with a previously owned Cherokee.

Hey everybody,

I am totally new to this board, so Hi.
I have 2 XJs, one is an 85 Wagoneer and the other is a 93 Sport. I was practically given the 85 because it was destined for the scrapyard (accident) However, I saved it and have gotten 3 years of dependable highway use, (even though it's a 3 speed) as well as 4-wheel drive use.

I bought this 93 back in June because my 85 has kinda had it. It was owned by this young guy who obviously mistreated it. Still, the price was good (2300) and, by all appearances, it was still a solid vehicle. Well, 4 months later, I am still trying to unravel a mistery. It IS a solid vehicle, but it has some problems.

It burns oil. It didn't when I got it, and I think that's because I just didn't open it up enough when I test drove it. However, it burns sporadically. I can sit there for 10 minutes and have nearly nothing for smoke, but if I get into the gas a little, it burns quite a bit. Further, if I hold the gas at 2 grand of so, it stops smoking. I believe that have a valve problem of some sort, but there's one problem: I am burning one quart per 800-900 miles. I did a compression test and I got 130 out of most of the cylinders, which isn't great, but isn't too bad either. The engine has TONS of power, and there isn't any lower end knocking at all. Everything looks like I have a valve problem, but can a valve problem be that bad where I would lose that much oil at such fast a rate? Oh, another thing: My oil pressure hovers around 20-30 all the time. I thought that this could have something to do with a possible valve problem, but I could be wrong. The engine is too well-performing for there to be a ring problem, you know? It has tons of kick (too much) it idles smoothly, isn't noisy, and just runs really well. I can hear upper-end niose though, and ths is another reason I suspect valves...but why so much oil consumption?

Thanks for any help!

Christian

Well, there you have it!

Two points:

1) The PCV system. Actually, "PCV" stands for Positive Crankcase Ventilation, and a PCV system commonly has a PCV valve. The XJ does not. That skinny little black plastic tube coming out of the back of the valve cover is what fulfills the PCV suction function, but there is no check valve. The other side of the circuit is the larger black tube off the front of the valve cover, to the air cleaner.

This system is supposed to suck air in through the air cleaner to the valve cover, then pull it back through that tiny tube to be burned in the engine. If that tube gets clogged and the engine has any blow-by (and what engine doesn't), the system pressurizes the crankcase and valve chamber and pushes oil out the front tube into the air cleaner. Check your air cleaner -- if it is oil-soaked, that's what's happening.

2) You may just need valve seals. These are little rubber or plastic "umbrellas" that fit over the valve stems to prevent the oil in the upper engine from running down the valve stems and into the combustion chamber. To replace, you remove the valve cover and use a special fitting in the spark plug hole to pressurize each cylinder. That holds the valves up (closed) while you pop off the valve springs and replace the little umbrellas.

3) Do you get oil spots on the ground at the rear of the engine? If so, you may need a rear main seal.

BTW -- I see you're from Maine. Check out the North Atlantic Chapter forum. We'll expect to see you in Bass Harbor in a week and a half

Concur - but I seem to want to think that the valve guide seals are "o-ring" type rather than "umbrella" in the 4.0 (at least, I didn't see any umbrellas when I had that 87 head apart right after my oil pump suffered a TSFF...)

Considering what my 220K rings looked like, I seriously doubt that's your problem. Clear the CCV lines, and recheck. If that doesn't do it, start thinking about doing valve guide seals...

5-90

Eagle said:

This system is supposed to suck air in through the air cleaner to the valve cover, then pull it back through that tiny tube to be burned in the engine. If that tube gets clogged and the engine has any blow-by (and what engine doesn't), the system pressurizes the crankcase and valve chamber and pushes oil out the front tube into the air cleaner. Check your air cleaner -- if it is oil-soaked, that's what's happening.

Click to expand...

Hey partner,

Am I correct in assuming that it is the other way around on the 4-cylinder engine? In other words, the pipe from the rear goes to the air filter and the one from the front goes to the intake manifold, right below the carb? Or did someone has messed up with my engine?????

Here you can see how the pipes go.



What on earth is going on??

Rgds

Thank you

Thank you for the info. I failed to mention that I had already gone the rounds with the PCV system (of sorts) and I had found a clogged breahter valve. I HAD had massive amounts of oil in my air filter, but that has stopped since I replaced the tube. I don't leak anything from the rear main, except that it IS a little wet. But, I parked in on concrete one night after driving it awhile, and by morning there were no leaks. Although a rear main problem would explain my oil pressure problem, it doesn't seem to. By the way, where can I get that tool to pressurize the cylinder? I am rather eager to see if this is in fact the problem. Like I said, this XJ is a dream: nice paint job, good suspension, the engine performs like brand new, and I just love XJs! But I am very eager to stop smelling blow-by, and very tired of filling it with oil. Ah well, such is life...

Hey, also, my 85 lost it's fual pump. I haven't even taken a look at it yet, but I think that the fuel pump is on the block rather than in the tank, anyone concur? Now that I have my 93 as my primary vehicle, the ol 85 might have a chance for some off-roading.


Take it easy,

Christian

Any auto parts store should have an adapter. It's just a fitting to screw into the spark plug hole. Then you add the correct fitting to mate up with a quick disconnect on your air hose and that's all there is to it. (I assume you have a compressor?)

BTW -- the rear main seal does not affect oil pressure. If you only have 20 to 30 psi at highway speeds, I would suspect worn rod bearings.

That's not good

I hope that it isn't my rod bearings, because niether me nor my budget are up to such a problem. But, I've put 15 thousand miles on it so far, and the oil pressure hasn't gotten any worse. I think that I'll drive it and keep an eye on the pressure, and just see what develops!

Christian

What weight oil are you using? Maybe it' too thin for worn out parts and you're getting some blow-by? Just curious...

Don't think that's the prob.

Good suggestion. However, I am running 10-30, and I highly doubt that I should run 10-40 in that 4.0, unless someone can show me a really good reason to. Anybody? ;-)

With the mileage you probably have, running 10W-40 isn't going to harm anything and may help. It is also a possibility to try mixing weights (I've done it before to stave off a rebuild I didn't have time for...) by using your 10W30 or 10W40 and replacing a quart or two with stright 40W or 50W racing oil to thicken things up a bit - but that's not generally recommended for wintertime if the average temperature is below 45* or so during the day (unless you have an oil heater already...)

You may also want to consider a decent "seal conditioner" to see if you valve guide seals can be renewed without cracking the case - some of those have been known to work.

5-90

John,
In the photo you provided the little silver thing on the front hose looks like a PCV valve. The PCV valve hose should be to the intake manifold.

It looks like yours is correct.

Tom

try an new oil pressure sending unit too. Its cheap and been know to tell a different story than the old one. BTW is there a problem with having too much oil pressure? After I replaced the rear main seal and oil pump(why? because it was right there to be changed while I did the rear main) I had to put a mechanical oil pressure gauge in after 2 oil pressure sending units died real quick. I crank up and oil pressure runs up to 70 when it starts cold, then stays at 50-60 running down the road and idles at 20 when hot.