Four Wheel Drive & Oil LEak

[1987BlackJeep]

1056442

(1) 4X4
I cannot get my '87 to go into 4 wheel drive (low or high)

It was working fine, then the jeep sat for about a week while
I was away and when i got back, no 4X4

Any ideas about the problem?

(2) Oil LEak

I have a slow oil leak, it seems to be coming from the engine, and I am thinking that it is either the valve cover gasket or the main seal.

The latter is a real ordeal to try and replace[addsig]

 

[JP]

1056444

(1) a: cant move the shifter?
b: or all of the wheels dont spin when you select 4hi or lo? if this is the case see post below yours regarding: 4x4 posi-lock---cable????

(2) Big difference between the two locations, try to figure out where its coming from best you can. a valve cover gasket is an easy fix, however main seal is quite a bit more work.
NEED MORE INFO!! :-? :-? :-? ;-)

edited by: JP, Feb 24, 2003 - 09:05 AM[addsig]

 

[1987BlackJeep]

1056446

I can move the stick into 4 HI or 4 L, but it remains in 2 wheel, meaning the front wheels are not spinning under load, no power to front wheels.

So, I can still drive and there appears to be nothing wrong with teh jeep, it is just not recognizing that I have shifted the stick into 4 wheel.

Very strange.



On the oil, yeah, I am trying to figure out where it is coming from, I had some leakage around the grommet, and there seems to be some leakage from the VC gasket. . . when I have the time I may just put in a new VC gasket and see if that stops the leak [addsig]

 

[Bullet3600]

1056448

I'm having the same problems with my XJ, Won't go into 4wd hi or lo. I checked for vacuum leaks and found none, then replaced the vacuum actuator unit on the front axle, still no 4wd :-x I just about ready to give up on it .......Bullet

PS. If you have a 4.0 the rear main seal only took me about 1 1/2 hrs to do the whole job[addsig]

 

[1987BlackJeep]

1056449

thanks, concerning the 4X4 i checked around and there did not appear to be anyhting out of place. :-? It is really BS though

I believe my 87 straight 6 is a 4.2 liter and i have read that replacing the rear main involves lifting the engine. . . so, hopefully it is not that! :[addsig]

 

[Bounty__Hunter]

1056479

Let's troubleshoot the 4wd system.

Start by pulling the 2-line vacuum connector from the vacuum shift motor on the front axle. With the Jeep running and in nuetral or park, have somebody shift the transfer case from 2wd to 4wd and back. There should be strong vacuum in one line for 4wd and the other for 2wd.

No vacuum or weak vacuum: problem is before the front axle. Check for cracked/broken vacuum lines. If all the lines check out and you're getting vacuum from the manifold to the transfer case, it could be a bad switch on the transfer case (4-vacuum line switch on pass. side of transfer case).

If vacuum is good to the front axle, the problem is in the vacuum shift motor. I recommend removing it (4 bolts) from the front axle and cleaning it, moving the shift fork by hand while spraying down with WD40. Spray WD40 into the vacuum ports while moving the shift fork.

Reassemble and try the 4wd.

Let me know what you find out, and I'll help the best I can.
Maybe this diagram will help you track down vacuum leaks:

[addsig]

 

[1987BlackJeep]

1056480

THanks, are all the hoses pictured running on the undercarriage?[addsig]

 

[JP]

1056498

Bounty:

you have piqued my own curiosity, and in assisting black jeep, does the 4WD indicator on the dash only go on once the vaccum actuator has engaged the front axle?

-JP[addsig]

 

[MORGSTER]

1056500

I feel your pain.
Before you go to the extreme of pulling your motor. Over the years I have had a lot of sleepless nights just trying to find my illusive leaks. In most all cases the culprit was something very small. If I took the position of major surgery every, or any time I had a Jeep problem, I would be broke.
My 1989YJ 4.2 had a leak dripping onto the exhaust crossover pipe and back across the transfer case that drove me nuts. (“Rear seal $200.00 Said the mechanic). No, it was oil in the air cleaner overflowing through a rivet hole and down along the block past the rear seal area onto the pipe. Once I found the leak, it was another chore figuring out why oil was in the air cleaner in the first place. Another Jeep mechanic I asked had said “Bad rings or valves and a rebuild was in order” again wrong. The actual reason was a small orifice in the PCV system needed to be sprayed with gumout to clean excess sludge. If I had taken the mechanics advice, the cost would have been thousands. Actual cost to fix four years ago was $1.88.
In conclusion, 95+% of my major Jeep problems have been minor fixes.
[addsig]

 

[1987BlackJeep]

1056501

To add my 2 cents, the 4wd indicator on my dash is NOT going on.

And now that I think about it, last time I successfully engaged the 4WD,
I had a hard time disengaging it. . . in other words I pushed the stick
it 2wheel and the 4WD dash indicator stayed on, and did not go off
until i flipped the stick back and forth a few times

(needless to say, trying to engage by using the same toggle is not working--- ) [addsig]

 

[MORGSTER]

1056502

When the shift motor is engaged on the front axle, vacuum is transfered to a switch on the firewall under the battery, which then creates a contact to allow ground to go to the indicator on the dash and light up.[addsig]

 

[1987BlackJeep]

1056503

Thanks on the leakage issue. I was finding oil in my
air cleaner until i replaced the grommet, but i am not sure
if i have the proper hose feading out of the grommet
(and I know i am missing the elbow valve that comes out
of the grommet).

The PCV is also gummed up pretty good, i could not even
remove it from the hose. . .

I spent about an hour and a half looking for the leak on sat.

Thought i got it. . . nope.[addsig]

 

[MORGSTER]

1056506

To understand how the system works might help to repair it.
On the dash is a light that tells you when you are in 4wd.
Under the battery (Passenger side) is a vacuum operated switch for the 4wd light (One wire to ground the other to the dash 4wd light).
The shift motor is where all of the vacuum hoses attach on the front axle.
From there to the drivers wheel (early Yj USA) is the long axle and to the passenger wheel is the short axle.
Inside the shift motor is a coupler that when engaged connects them both to be one axle.
On the shift motor there are three connections.
One vacuum line engages the coupler, and at the same time the second sends vacuum to the switch under the battery to ground the 4wd dash light.
The third is to disengage the coupler and at that time the vacuum is cut off the ground to the dash light switch, which turns off the light.


Things that can be bad are.
1. Inside the shift motor, the coupler is broken or it isn't installed correctly)(I find installation is usually the problem)
2.The vacuum lines are incorrectly routed or broken (Note: the colored plastic lines are very brittle with age. One leak and it won't work)(The Jeep will also run ruff)
3.The vacuum/light switch under the battery isn't grounded to the firewall correctly or it's broken (Usually it's loose and not grounded)
4. The dash light is not working (Bad bulb or wiring) (Usually it's the bulb)
Note: The wiring is simple. When vacuum is applied to the switch it connects the two wires inside and allows ground to the 4wd light (It lights up)
5. It just isn’t hooked up correctly or at all.

6. The transfer case shifter came loose or the linkage needs adjustment for full throw.
Look under the Jeep (Not running) have someone move the 4wd lever and see if it’s loose,(It will slide on the linkage shaft) unhooked, or needing adjustment.(Full forward and back, this usually happens with lifted Jeeps)
[addsig]

 

[MORGSTER]

1056507

Here is an old post I wrote that might help:

Regarding oil in the air cleaner.
I have been reading this same topic from forum to forum. Everything from removing valve covers to rebuilding motors because of warn or broken parts. Here is a suggestion from a Jeeper that had and fixed that same problem. I now have well over 225,000 miles on my daily driven, rock crawling, 1989 YJ. (With no oil in the air cleaner) . With help from the one non-salesperson at Jeep, I fixed the problem with a $1.88 can of gumout. With the engine running you can lift the pcv valve out of the valve cover and put your finger over the end and you should have some serious suction. (While reving the engine) If not, the pcv valve does sometime clog, (When you shake it, it should rattle) To clean he suggested spraying with gumout or replacing (if necessary). But the culprit is usually inside the hose that runs from the pcv valve to the intake manifold. If you removed the air cleaner you would find a split in that (approx ½ inch outside diameter) hose. It connects two hoses together. Inside is a small orifice (approx 1/8 inch inside diameter) that gets clogged very easily. (Trying to remove the two pieces usually ruins the orifice)(It gets brittle)
Before you remove anything, with the engine running, spray gumout into the pcv valve or remove it and spray directly into the hose (keeping the rpms up, so the engine won’t stall) Depending on the severity of the clog a little or a lot of gumout will be used. (Sometimes a piece of piano wire is needed to unblock the orifice) You should notice immediately a difference in the amount of suction at the pcv valve. Reinstall the valve, shut of the motor, open and clean the excess oil from inside the air cleaner. Replace, if necessary, the air filter (this is a good time to install a K&N filter) Remove the little filter, spray it with gumout, replace it and put back all the other parts. This completely fixed my problem. Two years to find and $1.88 and five minutes to fix.

Note: With this line clogged, the pressure inside the valve cover forces oil up through the rear hose into the air cleaner. And with so much oil inside and leaking out of the air cleaner, it leaves room for shady mechanics to suggest some serious $$$ repairs.

That repair was done about 50,000 miles ago, and just to be safe; I spray out that hose along with the carb during periodical maintenance. The problem never came back.

Give this a try. It solved my problem, and at $1.88 for a can of gumout, this might be the cheapest suggestion you’ll get.

Good Luck.


edited by: MORGSTER, Feb 24, 2003 - 03:56 PM[addsig]

 

[Bullet3600]

1056543

Now that I have unplugged my head from my butt, The last time my 4wd worked was just before I tore the engine apart to replace the head gasket. So checking out the diagram on the above posting I believe the manifold vacuum line is off somewhere. So my question is where would the manifold vacuum line originate on the 4.0?..............Bullet[addsig]

 

[Bounty__Hunter]

1056585

On the dash is a light that tells you when you are in 4wd.
Under the battery (Passenger side) is a vacuum operated switch for the 4wd light (One wire to ground the other to the dash 4wd light).

This is only on early model YJ's. Newer YJ's have an electrical switch in the vacuum disconnect motor on the front axle that operates the 4wd indicator light in the dash. Not sure of the cutoff year, but my '95 is electrical. My old '88 was vacuum to turn the light on.

If your 4wd light does not come on, then the shift fork in the front axle has likely not moved the collar locking the two axleshafts together.

When the tansfer case lever is moved to 4wd, the transfer is working correctly. The problem most often lies in the front axle disconnect system. Once you understand the system, it's not hard to work on and troubleshoot.[addsig]

 

[MORGSTER]

1056594

Bounty Hunter.

Thanks for the update. This is what makes forums great.

Teamwork :roll: :-O :-D [addsig]

 

[1987BlackJeep]

1056606

Thanks guys, I will let you know what happens.[addsig]

 

[cj572801]

1057622

I read your post about cleaning the pcv, cause of oil getting into the air filter, my
mechanic had told me the same thing, that my motor was wore out, and needed
rebuilt, and eventually would quit working, soon as i get the time, im going to try
that and i hope it works, i plan on putting a new motor in it soon anyway, but
its alot easier to get rid of a workin 4cyl motor then a non working one.[addsig]

 

[1987BlackJeep]

1057812

On the leak(s)

I replaced the PCV and some length of hose attached thereto, which was all gunked up- now there appears to be some better flow, which seems to have helped with the leak, at least there is less of a pool after i park the jeep.

It is really only a bunch of drops now.

However, either oil or coolant seems to be leaking near the front of the engine (i am thinking maybe the thermostat is shot).

Also, I noticed that a few of the hoses do not connect anywhere? Like one coming from the side of the carb, goes nowhere, so-- does anyone have a diagram or picture of where the engine hoses are supposed to go on an 87 straight six?

many thanks again

jwg
[addsig]