Instant Overheat
CF Veteran
Joined: Oct 2011
Posts: 4,440
Likes: 3
From: Seal Beach, CA
Year: 1996
Model: Cherokee
Engine: 4.0 HO Straight Six
Still think it's an electrical problem that's giving your gauge a false reading... I don't think it has to do with any of the components.
Try replacing the sensor that's at the rear driver's side of the head.
Try replacing the sensor that's at the rear driver's side of the head.
Junior Member
Joined: Jun 2012
Posts: 52
Likes: 0
From: Kentucky
Year: 1998
Model: Cherokee
Engine: 4L
Originally Posted by 9294Forrest
When my XJ is one line over 210 she's boiling water. After my radiator replacement from jeep she runs one line under 210
Junior Member
Joined: Jun 2012
Posts: 52
Likes: 0
From: Kentucky
Year: 1998
Model: Cherokee
Engine: 4L
Originally Posted by kennzz05
IT'S AIR IN THE COOLING SYSTEM, take our advice or stop asking for it.
[/QUOTE]Not touchy just want him to take our advice. Try what another member said and replace the sensor.
Thread Starter
Junior Member
Joined: Feb 2010
Posts: 73
Likes: 0
From: Naples FL
Year: 1999
Model: Cherokee
Engine: 4.0
When you put the t stat in did you put the correct side up? Did you put it in correctly? Try turning on the heat when you are filling the radiator. You have air trapped no doubt! Both radiator hoses should be the same temp as should both heater core hoses with the heat running. Don't waste your money at a computer tune place. IT'S AIR IN THE COOLING SYSTEM, take our advice or stop asking for it.
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 checked for air, didn't seem to be any and it's still doing it. My brother says he had to pull the hose off and fill his system on his older cummins truck to get the air out. I talked to a computer repair place and they said "maybe, bring it in and we'll check it" I guess it's my next step if I can't find something else. Does anyone know if those computer diagnostic plug in things read water temp. I would like to be able to read what the sending unit is saying verses what the computer says it's saying.
Driving along and all is normal. Then it jumps up in temp to one notch below pegged and does it in less than 2 seconds. I shut off air, keep driving and in about 5 - 15 minutes it drops again from hot to normal in less than 2 seconds. Never get any steam or antifreeze smell. Any thoughts?
CF ADMIN
Joined: Sep 2010
Posts: 34,088
Likes: 257
From: Lantana, Fl
Year: 1996
Model: Cherokee (XJ)
Engine: 4.Slow
The best way to fill the radiator and block with coolant is to take the upper radiator hose off the radiator end, hold it up and fill there. This will help remove a majority of the air pockets in the block and radiator.
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
this seems to be a common occurrences there numerous threads on it with no common cure,everything from new radiator cap to new cyl head has cured it...http://www.google.com/search?hl=en&r....0.UQGBrfX-CDQ
CF Veteran
Joined: Dec 2011
Posts: 4,006
Likes: 1
From: Pasadena, MD
Year: 1987
Model: Wagoneer
Engine: Renix 4.0
Driving along and all is normal. Then it jumps up in temp to one notch below pegged and does it in less than 2 seconds. I shut off air, keep driving and in about 5 - 15 minutes it drops again from hot to normal in less than 2 seconds. Never get any steam or antifreeze smell. Any thoughts?
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
when you say you shut off air, do you mean A/C? if you do that means that your aux fan isnt coming on, the pressure in the a/c system is building, and the condenser is getting stupid hot, which pre-heats the air in front of the radiator causing it to no be able to cool. hence why the temp jumps so badly.
Thread Starter
Junior Member
Joined: Feb 2010
Posts: 73
Likes: 0
From: Naples FL
Year: 1999
Model: Cherokee
Engine: 4.0
when you say you shut off air, do you mean A/C? if you do that means that your aux fan isnt coming on, the pressure in the a/c system is building, and the condenser is getting stupid hot, which pre-heats the air in front of the radiator causing it to no be able to cool. hence why the temp jumps so badly.
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 checked the wires to the computer and they are good. I have thought maybe a loose ground in the harness might cause erratic computer readings and will check them next chance I get if this mornings filling & burping doesn't do the trick.
I did this before she left for work this morning so I got my fingers crossed.
I thought the air (a\c) was effecting it at first but turns out it was just a coincidence. It does it with or with out the a\c on.
I did this before she left for work this morning so I got my fingers crossed.
I thought the air (a\c) was effecting it at first but turns out it was just a coincidence. It does it with or with out the a\c on.
