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XJ Ask the Question Thread
Herp Derp Jerp

Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
Junior Member
Joined: Apr 2015
Posts: 31
Likes: 1
From: Amarillo, TX
Year: 1998
Model: Grand Cherokee
Engine: 4.0
1998 XJ Limited 4.0 Inline, self-repair newb
So, for the last couple months I've had some fog coming out of my vents. Mostly in the morning when going uphill, vents always turned off. Figured it was the heater core going out right?
Well, this last weekend I replaced the valve cover gasket due to oil leakign. During the process I snapped the two evap lines running along the firewall behind the valve cover. Spliced and sealed them with electrical tape.
BAM, fog is gone. Week later and I saw just a wisp one day, but otherwise fixed. I am now confused on where the fog was coming from if not the heater core? The valve cover was not very tight, hence the leaking. And the back bolt hole on the cover is stripped and will only go in half way, was that way before I replaced the gasket, to be fixed later I guess.
Any ideas? I'm learning as I go, fixing problems I can see, but not sure how the systems connect in a way to cause/fix the fog issue.
So, for the last couple months I've had some fog coming out of my vents. Mostly in the morning when going uphill, vents always turned off. Figured it was the heater core going out right?
Well, this last weekend I replaced the valve cover gasket due to oil leakign. During the process I snapped the two evap lines running along the firewall behind the valve cover. Spliced and sealed them with electrical tape.
BAM, fog is gone. Week later and I saw just a wisp one day, but otherwise fixed. I am now confused on where the fog was coming from if not the heater core? The valve cover was not very tight, hence the leaking. And the back bolt hole on the cover is stripped and will only go in half way, was that way before I replaced the gasket, to be fixed later I guess.
Any ideas? I'm learning as I go, fixing problems I can see, but not sure how the systems connect in a way to cause/fix the fog issue.
No, I don't lick fish.



Joined: Mar 2011
Posts: 11,169
Likes: 26
From: Northern Kentucky
Year: 1999
Model: Cherokee (XJ)
Engine: 4.0
I got one of those screwdrivers too. I don't use it to hear anything but just to jab and pick up stray cardboard boxes or plastic bags that blew off my hood when I take parts out of them. Lol
CF Veteran
Joined: Nov 2013
Posts: 1,347
Likes: 0
From: Wetumpka, AL
Year: 1987
Model: Cherokee
Engine: 4.0
You could also drink a little liquid courage and sword fight with that thing...I've got a scar to prove it lol
Seasoned Member
Joined: Jun 2011
Posts: 334
Likes: 1
From: Cali
Year: 1999
Model: Cherokee
Engine: 4.0 L
Vehicle: '99 XJ, 4.0L engine, ax15 manual trans, 170,000 miles
Problem: Engine vibes between 2300-3500 RPM. With the vehicle parked I run the RPMs up to 3500 RPM. Between 2300-3500 RPM I can notice a significant vibration. If I apply pressure to the clutch I can feel major vibes through the clutch pedal. The vibes are worst after I run the RPMs up and right when I let off the throttle I get the worst vibes for about a second. I don't have any noticeable lose of power under acceleration. In an effort to fix the problem I replaced my worn out engine mounts and the problem still persists. I replaced the distributor cap, rotor, plugs and plug wires bout 15,000 miles ago.
What do you guys think? Do you think this is engine related or could it be the throw out bearing or something like that in my ax15? NO these are not drivline vibes its independent of speed. Please throw your ideas out there.
Problem: Engine vibes between 2300-3500 RPM. With the vehicle parked I run the RPMs up to 3500 RPM. Between 2300-3500 RPM I can notice a significant vibration. If I apply pressure to the clutch I can feel major vibes through the clutch pedal. The vibes are worst after I run the RPMs up and right when I let off the throttle I get the worst vibes for about a second. I don't have any noticeable lose of power under acceleration. In an effort to fix the problem I replaced my worn out engine mounts and the problem still persists. I replaced the distributor cap, rotor, plugs and plug wires bout 15,000 miles ago.
What do you guys think? Do you think this is engine related or could it be the throw out bearing or something like that in my ax15? NO these are not drivline vibes its independent of speed. Please throw your ideas out there.
Problem solved! After removing the belt and running the engine the vibration was gone. That isolated the vibration to one of the pullys. After doing some exploration under the hood I found the fan clutch and radiator fan were flopping around. The bearing on the clutch was compleatly fried, there were only 2 ball bearings left in the bearing races. After installing a $35 fan cluch the old XJ is smooth a silk!
To all reading this, I beg Ur opinion .... I have a '93 Country X J...
yesterday the oil gauge has taken to skip all over in the high range only.
It stays @ 12 o'clock until gas is applied..
then its all over the upper east side....
I looked for vacuum line issues.. alas there were none....
If in fact it is the oil pressure sensor ... where is it on the 4.0 ????
Thanks in advance for all of your collective brains.. its appreciated.
BTW.. the Jeep in question is for sale. Wifey can't drive it.. it's got to go..!
yesterday the oil gauge has taken to skip all over in the high range only.
It stays @ 12 o'clock until gas is applied..
then its all over the upper east side....
I looked for vacuum line issues.. alas there were none....
If in fact it is the oil pressure sensor ... where is it on the 4.0 ????
Thanks in advance for all of your collective brains.. its appreciated.
BTW.. the Jeep in question is for sale. Wifey can't drive it.. it's got to go..!
Last edited by Rain; Jun 7, 2015 at 03:53 PM.
Senior Member
Joined: Feb 2014
Posts: 854
Likes: 1
From: Minnesota
Year: 1996
Model: Cherokee
Engine: 4.0
To all reading this, I beg Ur opinion .... I have a '93 Country X J...
yesterday the oil gauge has taken to skip all over in the high range only.
It stays @ 12 o'clock until gas is applied..
then its all over the upper east side....
I looked for vacuum line issues.. alas there were none....
If in fact it is the oil pressure sensor ... where is it on the 4.0 ????
Thanks in advance for all of your collective brains.. its appreciated.
BTW.. the Jeep in question is for sale. Wifey can't drive it.. it's got to go..!
yesterday the oil gauge has taken to skip all over in the high range only.
It stays @ 12 o'clock until gas is applied..
then its all over the upper east side....
I looked for vacuum line issues.. alas there were none....
If in fact it is the oil pressure sensor ... where is it on the 4.0 ????
Thanks in advance for all of your collective brains.. its appreciated.
BTW.. the Jeep in question is for sale. Wifey can't drive it.. it's got to go..!
Moderator of Jeeps
Joined: Jul 2011
Posts: 21,029
Likes: 3
From: Frederick, MD from Cleveland, OH
Year: 1993 YJ Wrangler
Engine: 4.0 I6
Last edited by NewKindOfClown; Jun 8, 2015 at 04:19 PM.
Seasoned Member
Joined: Jun 2011
Posts: 334
Likes: 1
From: Cali
Year: 1999
Model: Cherokee
Engine: 4.0 L
I have exact same issue on my jeep right now. I know my left engine mount is shot, haven't had time to replace it. I can really feel harsh vibes on my gas pedal when engine speed get above 2500 rpms. I'm hoping u find your solution so I could look into it whenever I have time, ha





