Going to need someone with a stroke of genius for this one...
Member
Joined: Aug 2011
Posts: 103
Likes: 0
Model: Cherokee
These are just things I've come across in my 15yrs working on cars. ...Not often but I have seen it. And..the aux fan comes on 2 ways...when the temp sesor on the thermostat houseing tells the comp to turn it on..and when the a/c is on. I've seen jeeps, Envoys, trailblazers, escalades and yukons not run at all due to a faulty temp sensor....because it senses an overheat and shuts down....but thats just my 2cents...
CF Veteran
Joined: Mar 2010
Posts: 47,923
Likes: 38
From: Broward County Fl.
Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
I have a 90 and when I initially flushed and refilled my coolant system the normal way,I too had a vehicle that was running up to 260 quick and the fluid level never got lower in the reservoir.
Atrick a friend told me is to ensure you bleed the system well,is to:
Drain the system
Take off the T'stat Housing(Youll need to loosen your Serpentine belt at the Power Steering Pump to allow enough slack to get at the bottom Tstat bolt)
Remove the Tstat and drill a small bypass hole(s) in the T-stat flange (I drilled 4 of them,1 at 12 oclock,1 at 3,one at 6,and one at 9,I know OVERKILL)
Reinstall the T-stat and housing
Do not reinstall the upper radiator hose(yet)
Fill the system with coolant from the T-stat housing with a funnel(it takes a bit,and is a slow process) this will ensure you dont get any air pockets when you fire the vehicle up.
Im not saying this is any kind of Gospel,it was suggested to me and it worked well.
Atrick a friend told me is to ensure you bleed the system well,is to:
Drain the system
Take off the T'stat Housing(Youll need to loosen your Serpentine belt at the Power Steering Pump to allow enough slack to get at the bottom Tstat bolt)
Remove the Tstat and drill a small bypass hole(s) in the T-stat flange (I drilled 4 of them,1 at 12 oclock,1 at 3,one at 6,and one at 9,I know OVERKILL)
Reinstall the T-stat and housing
Do not reinstall the upper radiator hose(yet)
Fill the system with coolant from the T-stat housing with a funnel(it takes a bit,and is a slow process) this will ensure you dont get any air pockets when you fire the vehicle up.
Im not saying this is any kind of Gospel,it was suggested to me and it worked well.
Member
Joined: Aug 2011
Posts: 103
Likes: 0
Model: Cherokee
If your cap is bad on your resevior bottle on the renix system, you'll run hot. Its only a diaghram type cap...I have one...a 90..and a 96..by the way I'm parting out the 90...I also have a 94 and an 88 yj...
CF Veteran
Joined: Mar 2010
Posts: 47,923
Likes: 38
From: Broward County Fl.
Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
does the 90 have the vent windows that open drivers and passenger door?
CF Veteran
Joined: Mar 2010
Posts: 47,923
Likes: 38
From: Broward County Fl.
Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
I have a 90 and when I initially flushed and refilled my coolant system the normal way,I too had a vehicle that was running up to 260 quick and the fluid level never got lower in the reservoir.
Atrick a friend told me is to ensure you bleed the system well,is to:
Drain the system
Take off the T'stat Housing(Youll need to loosen your Serpentine belt at the Power Steering Pump to allow enough slack to get at the bottom Tstat bolt)
Remove the Tstat and drill a small bypass hole(s) in the T-stat flange (I drilled 4 of them,1 at 12 oclock,1 at 3,one at 6,and one at 9,I know OVERKILL)
Reinstall the T-stat and housing
Do not reinstall the upper radiator hose(yet)
Fill the system with coolant from the T-stat housing with a funnel(it takes a bit,and is a slow process) this will ensure you dont get any air pockets when you fire the vehicle up.
Im not saying this is any kind of Gospel,it was suggested to me and it worked well.
Atrick a friend told me is to ensure you bleed the system well,is to:
Drain the system
Take off the T'stat Housing(Youll need to loosen your Serpentine belt at the Power Steering Pump to allow enough slack to get at the bottom Tstat bolt)
Remove the Tstat and drill a small bypass hole(s) in the T-stat flange (I drilled 4 of them,1 at 12 oclock,1 at 3,one at 6,and one at 9,I know OVERKILL)
Reinstall the T-stat and housing
Do not reinstall the upper radiator hose(yet)
Fill the system with coolant from the T-stat housing with a funnel(it takes a bit,and is a slow process) this will ensure you dont get any air pockets when you fire the vehicle up.
Im not saying this is any kind of Gospel,it was suggested to me and it worked well.
CF Veteran
Joined: Apr 2010
Posts: 1,575
Likes: 4
From: Florida
Year: 2000
Model: Cherokee(XJ)
Engine: 4.6 Re-Built Golen, 68-200-4 Comp Cam
You're overheating for one reason or another. It shouldn't ever sit at 220. I have a 98 and when mine overheats (and man have I done it many times, and had to rebuild my engine) it will sit at 220 and then immediately jump to the other side. It DOESN'T steadily rise.
That's just the way the thing is. It's almost as if it's designed that way to get your attention since most people that don't do any maintenance don't pay attention to those things anyways.
Let's go through a check list of things you should be checking:
1. Mechanical fan, does it spin? If it's been dropped, thrown, or beat on with a hammer there is possible damage that has been done. Despite it's rugged look it has fluid in it and is designed to spin at some way that guys with IQ's way higher than mine understand.
2. Your auxillary fan works (when you turn on the AC it should kick on immediately) ? There are also a couple of fuses/relay in the box under the hood if it doesn't. But FIRST I would make sure it's plugged in. It CAN come unplugged despite the design. That alone can cause the overheat, especially when you turn on the AC. I know from experience when you turn on the AC, if that fan isn't plugged in you're going to run 15 degrees hotter. So operating temp is 210. That means 225. That means... it'll sit at 220, then jump to 260, beep and try to get your attention that you're in the danger zone.
3. Radiator cap, get it tested. It's supposed to maintain 16 PSI of pressure in the cooling system. I had a bad one of those and I kept loosing coolant from the overflow because it was overflowing, because when the cap loses PSI (and overheating frequently WILL wear a cap out) the boiling temperature of the coolant drops lower and causes it to run hotter which makes it expand further... thus overflowing after you stop and the engine heats up 10 more degrees.
4. The hoses going to the radiator. The one, in particular, at the bottom of the water pump leading to the bottom of the radiator. Is it SLIGHTLY collapsed? REPLACE IT. It shouldn't EVER be collapsed. That means its worn out. Because of the bends and location it is suspect to start doing that and reduce the flow of coolant... leading to overheating.
5. Heater core. If it's leaking, or has been for a long time, you're probably losing coolant into the cabin-air-intake, which is drying up and circulating into your breathable air. Trust me, you'll smell and see it when at full blast. It'll be like white powder. That one not so much, but over time it can cause a loss of coolant if you pay it no mind and never check the fluid. You'll also see a coolant leak in the passenger kick-panel area.
And remember, vote for CoffeeCommando for Member Of The Month.
That's just the way the thing is. It's almost as if it's designed that way to get your attention since most people that don't do any maintenance don't pay attention to those things anyways.
Let's go through a check list of things you should be checking:
1. Mechanical fan, does it spin? If it's been dropped, thrown, or beat on with a hammer there is possible damage that has been done. Despite it's rugged look it has fluid in it and is designed to spin at some way that guys with IQ's way higher than mine understand.
2. Your auxillary fan works (when you turn on the AC it should kick on immediately) ? There are also a couple of fuses/relay in the box under the hood if it doesn't. But FIRST I would make sure it's plugged in. It CAN come unplugged despite the design. That alone can cause the overheat, especially when you turn on the AC. I know from experience when you turn on the AC, if that fan isn't plugged in you're going to run 15 degrees hotter. So operating temp is 210. That means 225. That means... it'll sit at 220, then jump to 260, beep and try to get your attention that you're in the danger zone.
3. Radiator cap, get it tested. It's supposed to maintain 16 PSI of pressure in the cooling system. I had a bad one of those and I kept loosing coolant from the overflow because it was overflowing, because when the cap loses PSI (and overheating frequently WILL wear a cap out) the boiling temperature of the coolant drops lower and causes it to run hotter which makes it expand further... thus overflowing after you stop and the engine heats up 10 more degrees.
4. The hoses going to the radiator. The one, in particular, at the bottom of the water pump leading to the bottom of the radiator. Is it SLIGHTLY collapsed? REPLACE IT. It shouldn't EVER be collapsed. That means its worn out. Because of the bends and location it is suspect to start doing that and reduce the flow of coolant... leading to overheating.
5. Heater core. If it's leaking, or has been for a long time, you're probably losing coolant into the cabin-air-intake, which is drying up and circulating into your breathable air. Trust me, you'll smell and see it when at full blast. It'll be like white powder. That one not so much, but over time it can cause a loss of coolant if you pay it no mind and never check the fluid. You'll also see a coolant leak in the passenger kick-panel area.
And remember, vote for CoffeeCommando for Member Of The Month.
CF Veteran
Joined: Aug 2009
Posts: 1,047
Likes: 3
From: Hanover,Ont, Canada
Year: 1991
Model: Cherokee
Engine: 4.o
Hiya guys..the kit that is referred to is a sold by Snap-on, Matco...probably others, but I've never seen it in a store. Its expensive, and I know this because I use one. The liquid in it turns from blue to green if there are exhaust gases in the coolant. In any event. If the hoses get rock hard almost immediately, thats a sign of a blown head gasket. Pull every plug, see if any of them look like they've been steam cleaned, or have a color to them, usually green. Thats a sign of a head gasket problem. Take a compression test. If 2 adjacent cyliders have low compression....thats definately a head gasket. Oh and by the way, if you have a leak on your intake manifold....you can change everything in the cooling system and your still going to run hotter then normal, because that cylinder with the intake leak is going to run LEAN....and lean is hot. Take some brake clean, the non flammable kind, and spray every gasketed surface while its running. ANY change in idle, indicates a leak...As far as burping air constantly, that means that there is a leak in the cooling system. And that doesn't mean that you can see it.. Pull all the hoses, and clean the insides of them, and what they attach to, especially the water pump. Thats aluminum, and when you take the hose off you will notice a white powdery dust on it. Thats oxidation. Aluminum don't rot, it oxydizes. It will cause a bad seal. Use screw type clamps, the factory ones are a bi metal spring type that supposedly gets tighter as they heat up. I don't like them after a few years. In any event, if all thats good..your going to have to pressure test the system. Any good shop will have what you need and you can ask them to do it for you.....I know its long winded...but its what I do for a living....hope it helps...
Good luck!
Seasoned Member
Joined: Jul 2011
Posts: 322
Likes: 0
From: Sierra Vista AZ
Year: 1990
Model: Cherokee
Engine: 4.0
Seasoned Member
Joined: Aug 2011
Posts: 328
Likes: 0
From: washington
Year: 1987
Model: Cherokee
Engine: 4.0 6cyl
CF Veteran
Joined: Apr 2010
Posts: 1,575
Likes: 4
From: Florida
Year: 2000
Model: Cherokee(XJ)
Engine: 4.6 Re-Built Golen, 68-200-4 Comp Cam
Newbie
Joined: Aug 2011
Posts: 3
Likes: 0
Model: Cherokee
When the temp rises, the aux fan shuts off. The aux fan only runs when i first start the car, and i turn on the AC. When the car warms up and the aux fan shuts off, the AC still works. Of course, I eventually have to turn the AC off as my engine temp is starting to rise, then i get the pleasure of running the heater if i get caught in traffic.