Ralph77

Hopefully somebody who knows will post. Figure I own a gun and am curious. I run synthetic in my diffs. VV975. Wonder what, if anything, that would do to the temp. Stock covers by the way.

rcguymike

I've read that regular dino oil works better a dissipating heat than synthetic.

salad

That's the strangest thing I've ever heard. Synthetic lasts longer because the constituents aren't as prone to breaking down under heat and stress.

salad

Doesn't sound good... I'd change the oil with something cheap and then do a pressure test of the cooling system and see if you can force it to appear. I take it yours is a real 1999 and not some bastard 0331 right?

I hate the idea of downgrading to a '94 block but I'm not sure how to tell which component is busted without getting a machine shop involved.

Something tells me he doesn't have many minutes on his plan lol

rleymanii

Ok folks, here's one. My 1991 Cherokee Limited (4.0L) suddenly in the last few days threatens to stall when stopped at an intersection. Starts up fine, but then while still sitting in park, the motor tries to stall but usually recovers and the RPMs go up and down. Once rolling at speed, engine seems to be running fine. Does not threaten to stall every time while stopped with tranny in drive. I have had to pop it into neutral when stopped (which seems to help keep it from freaking out), then drop it back into drive to continue. Also, I notice the tach sometimes shows a higher rate (2000-2100rpm) at slow speed (25-30mph) then it used to (but not all the time), but the engine is not excessively revving.

Nothing has changed on the vehicle recently and this just started a few days ago. If it does stall, it starts right back up.

I am starting to suspect it maybe the crack shaft position sensor going bad, but I'm not sure.

Anybody got any ideas????

jj1031

I have a 200o Jeep Cherokee Sport 4WD. I never use 4WD. I just put it into 4 Lo on pavement and it made a bad noise when I turned the wheel. Thoughts?

SatiricalHen

you aren't supposed to use 4wd on dry pavement. Especially 4 low. It'll hop and pop and stuff because it's binding up.

cruiser54

Here's how the factory suggests you shift the transfer case and I've been doing this since these things were new and I worked at the dealership. Quoted from the owner's manual. The suggestions in CAPS are mine.

"To engage, shift the transfer case lever from 2H to 4H while the vehicle is moving at any legal speed". I LET OFF THE GAS, THROW THE LEVER, TAP THE GAS AND LET OFF.

4L position: " To engage, slow the vehicle to 2-3 MPH , shift the transmission to Neutral, then shift the transfer lever to the right and pull firmly rearward to 4L".

TO SHIFT OUT OF 4L, SHIFT THE TRANSMISSION INTO NEUTRAL WITH THE VEHICLE STOPPED, SHIFT THE TRANSFER CASE LEVER TO 2H, THEN THE TRANS TO D IF YOU HAVE AN AUTOMATIC, OR INTO FIRST GEAR WITH A MANUAL, AND CONTINUE ON.

Revised 11/20/2014

salad

The reason I asked is that some people claim there exists a unicorn out there, a late-build '99 that has '99 everything but somehow got a 0331 head in place of a 0630. You don't have the coil bosses, right??

Honestly I have no idea if there's anything in the block that would break and create that kind of leak. Any chance of finding another 0630? You can spend cash at the machine shop having the head checked but I think that the likelihood that it can be repaired is pretty low.

What a jerk!

Your 1991 will vary slightly, but start here: https://www.cherokeeforum.com/f51/th...eaning-179079/

Basslicks

Any luck with it yet? It sounds like you have more than one issue going on, really. You've indicated both a crank/no start as well as a no crank/no start. As far as the no crank/no start, when you turn the key, do you hear your fuel pump spool? If not, look at the MAP sensor as well. I bought a new MAP sensor that turned out to be faulty and it actually acted as an open circuit to the fuel pump... wouldn't spool and you could sit there and crank until the battery died without any startup whatsoever.


The crank/no-start could be fuel pump or several other things. Verify with a fuel pressure gauge before replacing Fuel Pressure Regulator, fuel pump, or fuel filter.

So how'd it go man? Dark fluid definitely warrants a change. I still wouldn't bother with the screen though - for the simple fact of how much detergent is in transmission fluid... nearly every transmission I've ever opened up - no matter how dark the fluid is - is squeaky clean on the inside. New tranny fluid would, in the end, self-clean that screen. BUT... if you're still paranoid, go for it.

How do you know what temperature it is? Are you using an IR gun or thermal imaging device? It's gonna feel hot in that engine compartment once the engine warms up regardless of whether or not it's operating at normal temp or higher. The 4.0's operating temps is between 210-230. That's where it's most happy. SO make sure you verify before you start trying to make it run cooler or you'll get it stuck in open loop and it will run rich and start guzzling more gas than it already does.

As Salad said, clean your IAC and throttle body. Should be done every once in a while regardless... ESPECIALLY if you have excessive blow-by causing oil to come out of the CCV ports.

Ralph77

Agree that is a strange statement too. But then again what do I know. I did it for a couple reasons. First it was a suggestion on improving MPG in a thread on another site. Second justified it by thinking that the diffs had the original fluid in them, plus whatever was added to top it off over the years, had a 150K on them, and needed to go.

Ralph77

That is pretty much how I shift mine in and out of 4 wheel drive to. My Jeep is just a DD. I am older now and my thrashing days are long over. Still doesn't mean I won't own a Jeep. When driving it around in the snow am constantly putting it in and taking it out of 4H depending on the road conditions. Some sections of road are plowed better then others. One of the reasons I am seriously considering a Select A Trac Transfer Case Swap. Even have a line on one from a '99 XJ. Might be as cheap as $70 for the TC, driveshafts, crossmember, and taking the gauge cluster too. Even though I have been trying to research this swap I am still a little unclear on what I will need. So my logic is grab anything even remotely associated it with it and sort it out later. Mine is a '00

SatiricalHen

going to get at least one new bearing in the front. Guy's coming to take it back to greenwood today.

Turbo X_J

If the road has been plowed at all there is no need for 4WD, drive for conditions and there is no need for the constant shifting.

SteveMongr

I have found that 135 -150 F is normal for highway driving.
For the front, it can depend on how long the truck has been running (pinion is close to the 450 degree exhaust pipes). And where you take reading from. Pinion area will likely see higher temps than diff cover/fluid.
If you suspect a bad pinon bearing, get a reading from the output shaft, there would likely be a temperature spike.