comancheman Posted June 3, 2008 Share Posted June 3, 2008 1989 4.0 still closed cooling system. all within the past year i have replaced thermostat, water pump, all hoses and the radiator. ive bled the system atleast 10 times. it has always warmed up to around 240* then backed down to 210* and stayed there. lately it keeps going back and forth between 210*and 240* usually staying around 220*-230* biggest temp increase is going up hills. i know 220* isnt bad but it wasnt always like this. next thing i was going to replace is the clutch fan. i kno there was a write up recently about the fan but i couldnt find it. am i correct in that it should be hard to spin when hot and easier to spin when cold? if anyone has a different idea I'm listening. thanks for your help, Tim Link to comment Share on other sites More sharing options...
chicofuentes0224 Posted June 3, 2008 Share Posted June 3, 2008 Are you going by what your gauge says? I was and it's definetly off on mine. Link to comment Share on other sites More sharing options...
summerinmaine Posted June 4, 2008 Share Posted June 4, 2008 Are you going by what your gauge says? I was and it's definetly off on mine. I suspect the same is true of mine. It rarely reads above 160 in normal use, and never above 210, even in the desert with full load uphill. Link to comment Share on other sites More sharing options...
maddzz1 Posted June 4, 2008 Share Posted June 4, 2008 Is it actually overheating? or is it just running hot according to the gauge? Link to comment Share on other sites More sharing options...
HOrnbrod Posted June 4, 2008 Share Posted June 4, 2008 1989 4.0 still closed cooling system. all within the past year i have replaced thermostat, water pump, all hoses and the radiator. ive bled the system atleast 10 times. it has always warmed up to around 240* then backed down to 210* and stayed there. lately it keeps going back and forth between 210*and 240* usually staying around 220*-230* biggest temp increase is going up hills. i know 220* isnt bad but it wasnt always like this. next thing i was going to replace is the clutch fan. i kno there was a write up recently about the fan but i couldnt find it. am i correct in that it should be hard to spin when hot and easier to spin when cold? if anyone has a different idea I'm listening.thanks for your help, Tim Had this same problem awhile back with my stock engine. Replaced everything in the coolant system. Turned out to be a clogged cat. Link to comment Share on other sites More sharing options...
comancheman Posted June 4, 2008 Author Share Posted June 4, 2008 i don't think the gauge is off and the temp sender is new also. i really think the fan is shot. i can easily spin it while either hot or cold. its a different car but the fan on my dads expedition doesnt turn nearly this easy. Link to comment Share on other sites More sharing options...
attaboybob Posted June 4, 2008 Share Posted June 4, 2008 Had this same problem awhile back with my stock engine. Replaced everything in the coolant system. Turned out to be a clogged cat. how do you know if the cat is blocked? BOB Link to comment Share on other sites More sharing options...
HOrnbrod Posted June 4, 2008 Share Posted June 4, 2008 I found it when I was repairing my exhaust system. When I unbolted the cat front flange and looked in, the inlet was clogged with a gummy tar looking mung. Pulled the cat and replaced it with a CarSound freeflow cat, overheating problems went away. If you have over 100K or so and still have the original cat, it's most likely shot. Link to comment Share on other sites More sharing options...
mvusse Posted June 4, 2008 Share Posted June 4, 2008 The stock temperature gauges are junk and not calibrated. To find out what your temperature really is, point a laser thermometer at the thermostat housing. Link to comment Share on other sites More sharing options...
chicofuentes0224 Posted June 4, 2008 Share Posted June 4, 2008 The stock temperature gauges are junk and not calibrated. To find out what your temperature really is, point a laser thermometer at the thermostat housing. I agree. You can buy one at autozone for $20. Make sure it's getting hot first before you start replacing unnecessary parts like I did. Link to comment Share on other sites More sharing options...
metrictonner Posted June 4, 2008 Share Posted June 4, 2008 When mine decided to run hot a few years ago I went through the same thing until I realized that the reverse rotation fan clutch that I got off of Ebay just might be standard rotation. So I went to a local parts store and bought one with the counterclockwise arrow still printed on it. Since then I've run with the gage nailed at 190 in any kind of weather. I assume the 1989 belt is a microgroove serpentine too which requires a reverse rotation fan clutch, just make sure it is. Link to comment Share on other sites More sharing options...
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