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Overheating after heater core bypass (NEED HELP!!)
#1
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Year: 1990
Model: Cherokee
Engine: 4.0L 6Cyl L8
Overheating after heater core bypass (NEED HELP!!)
SO, after going though posts on here for 3 days trying to see if I could figure out what was wrong I'm still lost.
I just got done giving her a MAJOR tune up (spark plugs, wires, dist. cap, rotor, ignition coil, fuel injectors, valve gasket, exhaust gasket, scrubbed the throttle body clean, TPS sensor, rad. fan temperature switch, new relay, new fuses, starter, brand new exhaust system, thermostat, air filter, oil change, rad. flush, new water pump, new rad. cap, loads of new hoses, and a $hit load more)
Anyways, after all that everything was running better then it had in quite awhile. The temp never rose above 210 ever.
Then when replacing some hoses the heater core got broke so we had to bypass it. I lost most of the coolant then so I flushed it and filled it back up (75% coolant 25% water) and it's overheating now.
It only overheats in slow traffic like in parking lots and at stop lights. I went 30 miles on the freeway with it staying right below operating temp. And the electric fan only comes on when the a/c is turned on (which I can't use right now, needs to be recharged :P)
I was reading that it could be the fan clutch so I've been checking it and I can't really feel a difference between when it's hot and when it's cold. When I spin it, it only goes down one blade so I'm not sure that's bad??
Either way I never had this problem until after I bypassed the heater core and had to flush the system.
Any help would be much appreciated!
I just got done giving her a MAJOR tune up (spark plugs, wires, dist. cap, rotor, ignition coil, fuel injectors, valve gasket, exhaust gasket, scrubbed the throttle body clean, TPS sensor, rad. fan temperature switch, new relay, new fuses, starter, brand new exhaust system, thermostat, air filter, oil change, rad. flush, new water pump, new rad. cap, loads of new hoses, and a $hit load more)
Anyways, after all that everything was running better then it had in quite awhile. The temp never rose above 210 ever.
Then when replacing some hoses the heater core got broke so we had to bypass it. I lost most of the coolant then so I flushed it and filled it back up (75% coolant 25% water) and it's overheating now.
It only overheats in slow traffic like in parking lots and at stop lights. I went 30 miles on the freeway with it staying right below operating temp. And the electric fan only comes on when the a/c is turned on (which I can't use right now, needs to be recharged :P)
I was reading that it could be the fan clutch so I've been checking it and I can't really feel a difference between when it's hot and when it's cold. When I spin it, it only goes down one blade so I'm not sure that's bad??
Either way I never had this problem until after I bypassed the heater core and had to flush the system.
Any help would be much appreciated!
#3
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Year: 1987
Model: Wagoneer
Engine: Renix 4.0
burp the coolant system. take the temp sender on the back of the head off, and fill the motor up with coolant until it starts spewing just coolant out of that hole. it helps if the rear end is parked uphill.
your electric fan is controlled by the ac compressor, and a sensor in the radiator in front of the airbox. if that sensor is bad, it will not turn on.
your electric fan is controlled by the ac compressor, and a sensor in the radiator in front of the airbox. if that sensor is bad, it will not turn on.
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Year: 1990
Model: Cherokee
Engine: 4.0L 6Cyl L8
Originally Posted by jakbob
burp the coolant system. take the temp sender on the back of the head off, and fill the motor up with coolant until it starts spewing just coolant out of that hole. it helps if the rear end is parked uphill.
your electric fan is controlled by the ac compressor, and a sensor in the radiator in front of the airbox. if that sensor is bad, it will not turn on.
your electric fan is controlled by the ac compressor, and a sensor in the radiator in front of the airbox. if that sensor is bad, it will not turn on.
And I just replaced the switch on the radiator in front/ below the air box and still nothing. The wiring diagram says there's a fusible link but I can't find any in line or in the fuse box.
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Year: 1987
Model: Wagoneer
Engine: Renix 4.0
Forgot to say I burped it like the book said, letting it get to temp with the cap off and filling. Would that bee good enough or should I do it from the sensor too?
And I just replaced the switch on the radiator in front/ below the air box and still nothing. The wiring diagram says there's a fusible link but I can't find any in line or in the fuse box.
And I just replaced the switch on the radiator in front/ below the air box and still nothing. The wiring diagram says there's a fusible link but I can't find any in line or in the fuse box.
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Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
where the top hose goes into your pressure bottle is there coolant shooting out into the pressure bottle when running?
#7
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Year: 1990
Model: Cherokee
Engine: 4.0L 6Cyl L8
Originally Posted by freegdr
where the top hose goes into your pressure bottle is there coolant shooting out into the pressure bottle when running?
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#8
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Year: 1996
Model: Cherokee
Engine: 4.0
A long shot but did the heater hoses accidentally get switched up? I don't know what that would do, but depending if you have a heater control valve still in place it could have been confusing.
#9
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Year: 1990
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#10
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Year: 1990
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Year: 1996
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that is the temp switch, yep.
edit: sorry I wasn't paying attention and assumed the loop would have gone a little less simple than that when i commented lol
edit: sorry I wasn't paying attention and assumed the loop would have gone a little less simple than that when i commented lol
Last edited by Fsher21; 05-22-2012 at 04:43 PM.
#12
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Year: 1990
Model: Cherokee
Engine: 4.0L 6Cyl L8
Originally Posted by Johnthepanpire
That tiny thing with the boot connector tucked back there?
#13
Well I think I am having the same problem....you are able to describe a lot of technical stuff...I had a water pump replaced and thermostat. My heater has been disconnected for some time my jeep shot from the 210 mark all the way to 260 in a matter of seconds. I am parked. I don't hear any hissing noises the car is not smoking so is it safe to drive 10 miles down the road to my house?
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Year: 1990
Model: Cherokee
Engine: 4.0L 6Cyl L8
Originally Posted by beckway66
Well I think I am having the same problem....you are able to describe a lot of technical stuff...I had a water pump replaced and thermostat. My heater has been disconnected for some time my jeep shot from the 210 mark all the way to 260 in a matter of seconds. I am parked. I don't hear any hissing noises the car is not smoking so is it safe to drive 10 miles down the road to my house?
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Year: 1990
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Originally Posted by jakbob
to the right of the airbox you will find the connection for the sensor and the ac control it is orange. and yes burp from the sensor too.
Thanks for the help so far everyone!