Another XJ overheating . . . . . .
10-05-2010, 04:27 PM
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Another XJ overheating . . . . . .
Hey all. New to the site here and somewhat new to XJs. Here's the situation: '89 XJ 4.0 automatic 4x4 is overheating. New:Radiator, factory Chrysler water pump, thermostat (2), reservoir cap (2-the first two blew off). We've been workin on this thing for over 2 weeks now trying to repair an overheating condition. I have researched quite extensively not only here but I've exhausted every other source of information I can think of. We've bypassed the heater core to eliminate that out of the equation also to no avail. The thing will fire up and run for about 10 minutes and then start steaming. Temperature all throughout the system (with laser thermo) is no hotter than 210 when vehicle begins to steam and appear to overheat. We did a block test as well to eliminate a faulty head gasket to no avail. I can't find one thing actually WRONG with this thing. I've read about a faulty reservoir causing similar issues but quite frankly I don't typically just start boltin parts on and guess. This shouldn't be that difficult but we're truly stumped.
10-05-2010, 04:46 PM
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10-05-2010, 04:53 PM
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Precisely. The temp guage is above normal but not in the "oh my god this thing is hot" range.
EDIT: We have also replaced the cooling fan switch. The temperature at the switch is about 140 right now with the vehicle running. Scan tool temp says right at 200. Guage is showing about 225. I just don't understand why we have such a huge difference in temperature throughout the system. The fan won't kick on until the system overheats.
EDIT: We have also replaced the cooling fan switch. The temperature at the switch is about 140 right now with the vehicle running. Scan tool temp says right at 200. Guage is showing about 225. I just don't understand why we have such a huge difference in temperature throughout the system. The fan won't kick on until the system overheats.
Last edited by anythingfast; 10-05-2010 at 05:07 PM.
10-05-2010, 05:08 PM
#5
Did you burp the living snot out of it? These thing trap a ton of air in them with out the filler on the radiator or in the upper hose. I fought this in both of mine until I saw the post on here one day sbout the in-line radiator neck. I changed mine first which is a DD and the kid's was just this last spring when he wanted to start driving it again every day.
The first fix I would do and have done to both of the 89s I own is changed them over to an open system by putting an in-line radiator cap in the upper line. I just changed the water pump and t-stat and with the open system it burped itself and I just put extra water in the overflow tank.
If you search for the conversion, there is a step by step process someone else has posted. Total time was about 30 mintes and $60 picking up the in-line filler at the parts hose and a new cap and overflow bottle.
The first fix I would do and have done to both of the 89s I own is changed them over to an open system by putting an in-line radiator cap in the upper line. I just changed the water pump and t-stat and with the open system it burped itself and I just put extra water in the overflow tank.
If you search for the conversion, there is a step by step process someone else has posted. Total time was about 30 mintes and $60 picking up the in-line filler at the parts hose and a new cap and overflow bottle.
10-05-2010, 05:08 PM
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stupid question. are the fans turning on.? mine has been over heating. i just installed new radiator, electric fan, therostat, and hood louvers. now the thing runs great.
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10-06-2010, 07:46 AM
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Did you burp the living snot out of it? These thing trap a ton of air in them with out the filler on the radiator or in the upper hose. I fought this in both of mine until I saw the post on here one day sbout the in-line radiator neck. I changed mine first which is a DD and the kid's was just this last spring when he wanted to start driving it again every day.
The first fix I would do and have done to both of the 89s I own is changed them over to an open system by putting an in-line radiator cap in the upper line. I just changed the water pump and t-stat and with the open system it burped itself and I just put extra water in the overflow tank.
If you search for the conversion, there is a step by step process someone else has posted. Total time was about 30 mintes and $60 picking up the in-line filler at the parts hose and a new cap and overflow bottle.
The first fix I would do and have done to both of the 89s I own is changed them over to an open system by putting an in-line radiator cap in the upper line. I just changed the water pump and t-stat and with the open system it burped itself and I just put extra water in the overflow tank.
If you search for the conversion, there is a step by step process someone else has posted. Total time was about 30 mintes and $60 picking up the in-line filler at the parts hose and a new cap and overflow bottle.
Snap On Solus w/the 2 part adapter that plugs into the diagnostic port under hood.
10-06-2010, 08:56 AM
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Definitely. I hate to admit it put we even drilled 1/8" hole in the thermostat to try to prevent air entrapment.
It has a new sending unit and temp sensor as well. The guage when we shut the engine off was at approximately 245-250 which is pretty close to the red mark (needles width away) and the hottest temp reading I could find with infrared thermo was 210 and I had to hunt for 210. At the temp. sending unit I was getting about 150'. Of course, that's on the outside of the sensor as opposed to the inside where it's actually getting it's reading but I don't see there being nearly 100' variance there. I think the temp guage is giving a false reading. We tried the following procedure and it seems to have helped immensely:http://en.allexperts.com/q/Jeep-785/...verheating.htm
So far so good. Will keep updated.
So far so good. Will keep updated.
10-06-2010, 10:11 AM
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Does the scan tool have enough cord for the display unit to sit on the dash, to be monitored under driving conditions? That's the gauge I'd rely on for accurate coolant temp readings while sorting out the issues.
10-06-2010, 10:27 AM
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Yes. Good suggestion. Been there done that though. Temp was steady at 210.
There were times when it would get up to 240 sitting here at idle but it would steam and overflow even when we were only at 200-210 @ the reservoir. I honestly and truly believe we got it nailed now.
10-06-2010, 11:24 AM
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I wouldn't think the scan tool would show a steady 210F but maybe. Are u talking about a hose clamp around the neck of the bottle? Screw type hose clamps are notorious for not applying even/equal pressure/clamping force. Converting to a "open system" (real rad pressure cap) may be better.
http://www.madxj.com/MADXJ/technical...stemSwitch.htm
http://www.madxj.com/MADXJ/technical...stemSwitch.htm
Last edited by djb383; 10-06-2010 at 11:28 AM.
