Sep 21, 2015, 03:49 PM
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XJ Ask the Question Thread
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,578
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Yes 4.0. This thing is well over due for a tune up anyway inspection due this month so I will be going to auto store to get valve cover gasket sounds about right since when I did the water pump I over heated the Damn thing and valve cover was basically sizzling. Thanks for the help.
I'd be looking up ABOVE first, and VERIFYING the source of the oil leak YOURSELF.
Everybody, who doesn't own or have to pay for or perform your vehicle repairs, loves to poke their noggin UNDER the Jeep and come out bearing the false bad news that your RMS is leaking.
Many mechanics, friends, people on Jeep forums who can’t see your Jeep from where they’re at, and good old Uncle Bob seem to enjoy telling you it’s the rear main seal. Has a catastrophic ring to it, doesn’t it?
A simple leak at the back of the valve cover or other source could produce the same symptoms. You don’t need to be a mechanic to figure this out. If you have good eyesight and a dim flashlight, you’re good to go on your own. Don't jump on the RMS/oil pan gasket bandwagon right off the bat.
Almost any oil leak on your 4.0 is gonna drip from the RMS area for two simple reasons.
First off, the engine sits nose-up and any oil will run back to the RMS area. Secondly, the RMS area is also the lowest point on the engine. Simple physics and the old plumber's adage apply here. "$hit flows downhill".
Valve cover gasket, oil pressure sending unit, oil filter adapter seals and distributor gasket, in that order, have to be eliminated as possibilities first.
Revised 02-26-2013
Newbie
Joined: Apr 2014
Posts: 5
Likes: 0
From: ny
Year: 1996
Model: Cherokee
Engine: 4.0
Bought a 500 dollar 96 Cherokee Sport w/ 4.0 and 4 wheel drive. got it cheap because of blown head gasket and non-existent floor boards, which I welded in a whole new floor pan set.
I replaced the blown gasket (had a definite hole between #4 and #5 cyl) with a new fel-pro one. head was in spec for flatness and was torqed to spec and #11 bolt threads were sealed. of course some idiot used TONS of stop leak and she still over heats. while the head was off, I dug out (and blew clean with compressed air) the PLUGGED coolant ports in the head and they are clean as a whistle. water pump looks new and today I removed the radiator and flushed and shook it about 50 times and got it to flow real good in both directions, reinstalled rad, and a new 180° Stant thermostat. also flushed the engine and it seems to flow ok. no overheating while idling in the driveway only when I drive it. any other ideas?
clutch on the belt driven fan is good, when you rev the engine the fan will blow your hat off into the next county and it has good resistance when you turn it by hand with the engine off. the electric fan works as it should.
my next step tomorrow will be pull the t-stat back out, add some coolant system cleaner with plain water and drive it a couple days with no t-stat, drain, flush with clean water again, refill and see what I got. if it don't work, I guess I need to pull the water pump and inspect the vanes on the impeller. only other thing it could be is the block water ports plugged too? both hoses get hard when it overheating. heater core has good flow both ways(I have good heat) and there are no coolant leaks anywhere including internal. If I get no results after the cleaning and inspecting the pump, I guess I gotta pull the head again, and recheck the block ports. Hope I don't have to do that!
I replaced the blown gasket (had a definite hole between #4 and #5 cyl) with a new fel-pro one. head was in spec for flatness and was torqed to spec and #11 bolt threads were sealed. of course some idiot used TONS of stop leak and she still over heats. while the head was off, I dug out (and blew clean with compressed air) the PLUGGED coolant ports in the head and they are clean as a whistle. water pump looks new and today I removed the radiator and flushed and shook it about 50 times and got it to flow real good in both directions, reinstalled rad, and a new 180° Stant thermostat. also flushed the engine and it seems to flow ok. no overheating while idling in the driveway only when I drive it. any other ideas?
clutch on the belt driven fan is good, when you rev the engine the fan will blow your hat off into the next county and it has good resistance when you turn it by hand with the engine off. the electric fan works as it should.
my next step tomorrow will be pull the t-stat back out, add some coolant system cleaner with plain water and drive it a couple days with no t-stat, drain, flush with clean water again, refill and see what I got. if it don't work, I guess I need to pull the water pump and inspect the vanes on the impeller. only other thing it could be is the block water ports plugged too? both hoses get hard when it overheating. heater core has good flow both ways(I have good heat) and there are no coolant leaks anywhere including internal. If I get no results after the cleaning and inspecting the pump, I guess I gotta pull the head again, and recheck the block ports. Hope I don't have to do that!
don't normally quote myself, but wanted to remind the folks here of my issue. I got the flush chemical, pulled the t-stat, flushed a ton more crap out, added the flush and filled with clean water. here is where it gets weird, the hoses were still mighty hard while running with no t-stat and its got pretty good heat. I ran it for a while and drove it a couple miles with the flush in the system and the temp was around 170°. drained and flushed the system again and pulled the water pump and inspected it. doesn't seem to be anything wrong with the impeller, it was clean, the bearing and the vanes are good, it is indeed a new pump. thinking I need another rad. if that don't solve it I guess I have to think about pulling the head again and inspect the block coolant ports.
Had the same problem. This may sound off a little, but it worked. Get some MEAN GREEN and add it to the system after you remove the t-stat and flush. I used the hose from the top of the t-stat housing to back flush it. I also used some bleach clean stuff too. seemed to solve the problem. Don't forget to drill two little holes in the t-stat, it works!!
Herp Derp Jerp
Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
I highly doubt a popup is going to even approach that. 1500 lbs maybe lol
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,578
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
CF Veteran
Joined: Apr 2011
Posts: 4,825
Likes: 2
From: Indianapolis
Year: '99 and '91
Model: Cherokee
That's a lot more than 3500. I do need to get a better trans cooler. I smashed a bunch if fins last time I was in that area.
CF Veteran
Joined: Sep 2010
Posts: 12,692
Likes: 6
From: Mercer County, NJ
Year: 2001
Model: Cherokee
Engine: 4.0L I6 HO
Just do a Google search. Its pretry much both a waste of money and more for high RPM stuff. Nothing beneficial for a jeep. Works better with carbs
CF Veteran
Joined: Sep 2010
Posts: 12,692
Likes: 6
From: Mercer County, NJ
Year: 2001
Model: Cherokee
Engine: 4.0L I6 HO
