Kurt C. Hack

1987 Cherokee with 4.0L and automatic transmission overheats all the
time. I have replaced the following:
Radiator
Temperature Sending Unit
Thermostat
Thermostat Housing
Heater Core
Recovery Bottle Cap
Fan Clutch
Spark Plugs
Spark Plug Wires
Rotor
Distributor Cap

I have also had the water pump checked and the coolant checked for
exhaust gasses. Both passed fine.

I can bleed the air out of the system and it will do fine for one run
cycle. However, when I turn it off and let it cool, the next time I
start it will start the overheating again. The overheating gets
progressively worse with each hot\cold cycle of the engine until I bleed
the air back out of the system.

I can get heat out of the heater and can see the coolant moving in the
recovery bottle. The upper and lower radiator hoses are also hot. Thus,
the thermostat and water pump are known good.

No evident leaks of coolant while sitting, unless its started
overheating, in which case it comes out of the recovery bottle at the cap.

Any ideas, or is it time for the scrapyard? I had the head gasket
replaced awhile back, and one mechanic mentioned that they might have
blocked a coolant passage, and thoughts on this random thought?

Thanks guys!

-Kurt

Mike Romain

I am missing something here.

How are you 'bleeding' the air out of the system?

Once you have flow to the heater core and the recovery bottle, the air
is gone.

Are you sure your temperature gauge isn't just bad? They are well known
to not be very accurate.

Do you have the coolant in the bottle near the bottom of it when cold?
If overfilled it will **** out on the ground until it finds it's proper
running level to allow for hot expansion.

In other words are you sure it's overheating?

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

"Kurt C. Hack" wrote:
>
> 1987 Cherokee with 4.0L and automatic transmission overheats all the
> time. I have replaced the following:
> Radiator
> Temperature Sending Unit
> Thermostat
> Thermostat Housing
> Heater Core
> Recovery Bottle Cap
> Fan Clutch
> Spark Plugs
> Spark Plug Wires
> Rotor
> Distributor Cap
>
> I have also had the water pump checked and the coolant checked for
> exhaust gasses. Both passed fine.
>
> I can bleed the air out of the system and it will do fine for one run
> cycle. However, when I turn it off and let it cool, the next time I
> start it will start the overheating again. The overheating gets
> progressively worse with each hot\cold cycle of the engine until I bleed
> the air back out of the system.
>
> I can get heat out of the heater and can see the coolant moving in the
> recovery bottle. The upper and lower radiator hoses are also hot. Thus,
> the thermostat and water pump are known good.
>
> No evident leaks of coolant while sitting, unless its started
> overheating, in which case it comes out of the recovery bottle at the cap.
>
> Any ideas, or is it time for the scrapyard? I had the head gasket
> replaced awhile back, and one mechanic mentioned that they might have
> blocked a coolant passage, and thoughts on this random thought?
>
> Thanks guys!
>
> -Kurt

Mike Romain

I am missing something here.

How are you 'bleeding' the air out of the system?

Once you have flow to the heater core and the recovery bottle, the air
is gone.

Are you sure your temperature gauge isn't just bad? They are well known
to not be very accurate.

Do you have the coolant in the bottle near the bottom of it when cold?
If overfilled it will **** out on the ground until it finds it's proper
running level to allow for hot expansion.

In other words are you sure it's overheating?

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

"Kurt C. Hack" wrote:
>
> 1987 Cherokee with 4.0L and automatic transmission overheats all the
> time. I have replaced the following:
> Radiator
> Temperature Sending Unit
> Thermostat
> Thermostat Housing
> Heater Core
> Recovery Bottle Cap
> Fan Clutch
> Spark Plugs
> Spark Plug Wires
> Rotor
> Distributor Cap
>
> I have also had the water pump checked and the coolant checked for
> exhaust gasses. Both passed fine.
>
> I can bleed the air out of the system and it will do fine for one run
> cycle. However, when I turn it off and let it cool, the next time I
> start it will start the overheating again. The overheating gets
> progressively worse with each hot\cold cycle of the engine until I bleed
> the air back out of the system.
>
> I can get heat out of the heater and can see the coolant moving in the
> recovery bottle. The upper and lower radiator hoses are also hot. Thus,
> the thermostat and water pump are known good.
>
> No evident leaks of coolant while sitting, unless its started
> overheating, in which case it comes out of the recovery bottle at the cap.
>
> Any ideas, or is it time for the scrapyard? I had the head gasket
> replaced awhile back, and one mechanic mentioned that they might have
> blocked a coolant passage, and thoughts on this random thought?
>
> Thanks guys!
>
> -Kurt

Mike Romain

I am missing something here.

How are you 'bleeding' the air out of the system?

Once you have flow to the heater core and the recovery bottle, the air
is gone.

Are you sure your temperature gauge isn't just bad? They are well known
to not be very accurate.

Do you have the coolant in the bottle near the bottom of it when cold?
If overfilled it will **** out on the ground until it finds it's proper
running level to allow for hot expansion.

In other words are you sure it's overheating?

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

"Kurt C. Hack" wrote:
>
> 1987 Cherokee with 4.0L and automatic transmission overheats all the
> time. I have replaced the following:
> Radiator
> Temperature Sending Unit
> Thermostat
> Thermostat Housing
> Heater Core
> Recovery Bottle Cap
> Fan Clutch
> Spark Plugs
> Spark Plug Wires
> Rotor
> Distributor Cap
>
> I have also had the water pump checked and the coolant checked for
> exhaust gasses. Both passed fine.
>
> I can bleed the air out of the system and it will do fine for one run
> cycle. However, when I turn it off and let it cool, the next time I
> start it will start the overheating again. The overheating gets
> progressively worse with each hot\cold cycle of the engine until I bleed
> the air back out of the system.
>
> I can get heat out of the heater and can see the coolant moving in the
> recovery bottle. The upper and lower radiator hoses are also hot. Thus,
> the thermostat and water pump are known good.
>
> No evident leaks of coolant while sitting, unless its started
> overheating, in which case it comes out of the recovery bottle at the cap.
>
> Any ideas, or is it time for the scrapyard? I had the head gasket
> replaced awhile back, and one mechanic mentioned that they might have
> blocked a coolant passage, and thoughts on this random thought?
>
> Thanks guys!
>
> -Kurt

Mike Romain

I am missing something here.

How are you 'bleeding' the air out of the system?

Once you have flow to the heater core and the recovery bottle, the air
is gone.

Are you sure your temperature gauge isn't just bad? They are well known
to not be very accurate.

Do you have the coolant in the bottle near the bottom of it when cold?
If overfilled it will **** out on the ground until it finds it's proper
running level to allow for hot expansion.

In other words are you sure it's overheating?

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

"Kurt C. Hack" wrote:
>
> 1987 Cherokee with 4.0L and automatic transmission overheats all the
> time. I have replaced the following:
> Radiator
> Temperature Sending Unit
> Thermostat
> Thermostat Housing
> Heater Core
> Recovery Bottle Cap
> Fan Clutch
> Spark Plugs
> Spark Plug Wires
> Rotor
> Distributor Cap
>
> I have also had the water pump checked and the coolant checked for
> exhaust gasses. Both passed fine.
>
> I can bleed the air out of the system and it will do fine for one run
> cycle. However, when I turn it off and let it cool, the next time I
> start it will start the overheating again. The overheating gets
> progressively worse with each hot\cold cycle of the engine until I bleed
> the air back out of the system.
>
> I can get heat out of the heater and can see the coolant moving in the
> recovery bottle. The upper and lower radiator hoses are also hot. Thus,
> the thermostat and water pump are known good.
>
> No evident leaks of coolant while sitting, unless its started
> overheating, in which case it comes out of the recovery bottle at the cap.
>
> Any ideas, or is it time for the scrapyard? I had the head gasket
> replaced awhile back, and one mechanic mentioned that they might have
> blocked a coolant passage, and thoughts on this random thought?
>
> Thanks guys!
>
> -Kurt

Kurt C. Hack

I am bleeding the air out by jacking up the rear of the vehicle and
removing the temp sensor at the back of the motor until all the air
escapes and only the coolant is flowing.

The temp sender has been replaced and I have checked the value coming
from it compared to what the gauge states, so the gauge and the temp
sender is known good.

I have gone through the process of letting the system "right" itself
after refilling and bleeding the system. After that its OK for the
first run cycle. However, after letting it cool overnight its starts
the process again of overheating. The problem becomes progressively
worse until I refill and bleed the system again.

Thanks,
-Kurt

Mike Romain wrote:

> I am missing something here.
>
> How are you 'bleeding' the air out of the system?
>
> Once you have flow to the heater core and the recovery bottle, the air
> is gone.
>
> Are you sure your temperature gauge isn't just bad? They are well known
> to not be very accurate.
>
> Do you have the coolant in the bottle near the bottom of it when cold?
> If overfilled it will **** out on the ground until it finds it's proper
> running level to allow for hot expansion.
>
> In other words are you sure it's overheating?
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> "Kurt C. Hack" wrote:
>
>>1987 Cherokee with 4.0L and automatic transmission overheats all the
>>time. I have replaced the following:
>> Radiator
>> Temperature Sending Unit
>> Thermostat
>> Thermostat Housing
>> Heater Core
>> Recovery Bottle Cap
>> Fan Clutch
>> Spark Plugs
>> Spark Plug Wires
>> Rotor
>> Distributor Cap
>>
>>I have also had the water pump checked and the coolant checked for
>>exhaust gasses. Both passed fine.
>>
>>I can bleed the air out of the system and it will do fine for one run
>>cycle. However, when I turn it off and let it cool, the next time I
>>start it will start the overheating again. The overheating gets
>>progressively worse with each hot\cold cycle of the engine until I bleed
>>the air back out of the system.
>>
>>I can get heat out of the heater and can see the coolant moving in the
>>recovery bottle. The upper and lower radiator hoses are also hot. Thus,
>>the thermostat and water pump are known good.
>>
>>No evident leaks of coolant while sitting, unless its started
>>overheating, in which case it comes out of the recovery bottle at the cap.
>>
>>Any ideas, or is it time for the scrapyard? I had the head gasket
>>replaced awhile back, and one mechanic mentioned that they might have
>>blocked a coolant passage, and thoughts on this random thought?
>>
>>Thanks guys!
>>
>>-Kurt

Kurt C. Hack

I am bleeding the air out by jacking up the rear of the vehicle and
removing the temp sensor at the back of the motor until all the air
escapes and only the coolant is flowing.

The temp sender has been replaced and I have checked the value coming
from it compared to what the gauge states, so the gauge and the temp
sender is known good.

I have gone through the process of letting the system "right" itself
after refilling and bleeding the system. After that its OK for the
first run cycle. However, after letting it cool overnight its starts
the process again of overheating. The problem becomes progressively
worse until I refill and bleed the system again.

Thanks,
-Kurt

Mike Romain wrote:

> I am missing something here.
>
> How are you 'bleeding' the air out of the system?
>
> Once you have flow to the heater core and the recovery bottle, the air
> is gone.
>
> Are you sure your temperature gauge isn't just bad? They are well known
> to not be very accurate.
>
> Do you have the coolant in the bottle near the bottom of it when cold?
> If overfilled it will **** out on the ground until it finds it's proper
> running level to allow for hot expansion.
>
> In other words are you sure it's overheating?
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> "Kurt C. Hack" wrote:
>
>>1987 Cherokee with 4.0L and automatic transmission overheats all the
>>time. I have replaced the following:
>> Radiator
>> Temperature Sending Unit
>> Thermostat
>> Thermostat Housing
>> Heater Core
>> Recovery Bottle Cap
>> Fan Clutch
>> Spark Plugs
>> Spark Plug Wires
>> Rotor
>> Distributor Cap
>>
>>I have also had the water pump checked and the coolant checked for
>>exhaust gasses. Both passed fine.
>>
>>I can bleed the air out of the system and it will do fine for one run
>>cycle. However, when I turn it off and let it cool, the next time I
>>start it will start the overheating again. The overheating gets
>>progressively worse with each hot\cold cycle of the engine until I bleed
>>the air back out of the system.
>>
>>I can get heat out of the heater and can see the coolant moving in the
>>recovery bottle. The upper and lower radiator hoses are also hot. Thus,
>>the thermostat and water pump are known good.
>>
>>No evident leaks of coolant while sitting, unless its started
>>overheating, in which case it comes out of the recovery bottle at the cap.
>>
>>Any ideas, or is it time for the scrapyard? I had the head gasket
>>replaced awhile back, and one mechanic mentioned that they might have
>>blocked a coolant passage, and thoughts on this random thought?
>>
>>Thanks guys!
>>
>>-Kurt

Kurt C. Hack

I am bleeding the air out by jacking up the rear of the vehicle and
removing the temp sensor at the back of the motor until all the air
escapes and only the coolant is flowing.

The temp sender has been replaced and I have checked the value coming
from it compared to what the gauge states, so the gauge and the temp
sender is known good.

I have gone through the process of letting the system "right" itself
after refilling and bleeding the system. After that its OK for the
first run cycle. However, after letting it cool overnight its starts
the process again of overheating. The problem becomes progressively
worse until I refill and bleed the system again.

Thanks,
-Kurt

Mike Romain wrote:

> I am missing something here.
>
> How are you 'bleeding' the air out of the system?
>
> Once you have flow to the heater core and the recovery bottle, the air
> is gone.
>
> Are you sure your temperature gauge isn't just bad? They are well known
> to not be very accurate.
>
> Do you have the coolant in the bottle near the bottom of it when cold?
> If overfilled it will **** out on the ground until it finds it's proper
> running level to allow for hot expansion.
>
> In other words are you sure it's overheating?
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> "Kurt C. Hack" wrote:
>
>>1987 Cherokee with 4.0L and automatic transmission overheats all the
>>time. I have replaced the following:
>> Radiator
>> Temperature Sending Unit
>> Thermostat
>> Thermostat Housing
>> Heater Core
>> Recovery Bottle Cap
>> Fan Clutch
>> Spark Plugs
>> Spark Plug Wires
>> Rotor
>> Distributor Cap
>>
>>I have also had the water pump checked and the coolant checked for
>>exhaust gasses. Both passed fine.
>>
>>I can bleed the air out of the system and it will do fine for one run
>>cycle. However, when I turn it off and let it cool, the next time I
>>start it will start the overheating again. The overheating gets
>>progressively worse with each hot\cold cycle of the engine until I bleed
>>the air back out of the system.
>>
>>I can get heat out of the heater and can see the coolant moving in the
>>recovery bottle. The upper and lower radiator hoses are also hot. Thus,
>>the thermostat and water pump are known good.
>>
>>No evident leaks of coolant while sitting, unless its started
>>overheating, in which case it comes out of the recovery bottle at the cap.
>>
>>Any ideas, or is it time for the scrapyard? I had the head gasket
>>replaced awhile back, and one mechanic mentioned that they might have
>>blocked a coolant passage, and thoughts on this random thought?
>>
>>Thanks guys!
>>
>>-Kurt

Kurt C. Hack

I am bleeding the air out by jacking up the rear of the vehicle and
removing the temp sensor at the back of the motor until all the air
escapes and only the coolant is flowing.

The temp sender has been replaced and I have checked the value coming
from it compared to what the gauge states, so the gauge and the temp
sender is known good.

I have gone through the process of letting the system "right" itself
after refilling and bleeding the system. After that its OK for the
first run cycle. However, after letting it cool overnight its starts
the process again of overheating. The problem becomes progressively
worse until I refill and bleed the system again.

Thanks,
-Kurt

Mike Romain wrote:

> I am missing something here.
>
> How are you 'bleeding' the air out of the system?
>
> Once you have flow to the heater core and the recovery bottle, the air
> is gone.
>
> Are you sure your temperature gauge isn't just bad? They are well known
> to not be very accurate.
>
> Do you have the coolant in the bottle near the bottom of it when cold?
> If overfilled it will **** out on the ground until it finds it's proper
> running level to allow for hot expansion.
>
> In other words are you sure it's overheating?
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> "Kurt C. Hack" wrote:
>
>>1987 Cherokee with 4.0L and automatic transmission overheats all the
>>time. I have replaced the following:
>> Radiator
>> Temperature Sending Unit
>> Thermostat
>> Thermostat Housing
>> Heater Core
>> Recovery Bottle Cap
>> Fan Clutch
>> Spark Plugs
>> Spark Plug Wires
>> Rotor
>> Distributor Cap
>>
>>I have also had the water pump checked and the coolant checked for
>>exhaust gasses. Both passed fine.
>>
>>I can bleed the air out of the system and it will do fine for one run
>>cycle. However, when I turn it off and let it cool, the next time I
>>start it will start the overheating again. The overheating gets
>>progressively worse with each hot\cold cycle of the engine until I bleed
>>the air back out of the system.
>>
>>I can get heat out of the heater and can see the coolant moving in the
>>recovery bottle. The upper and lower radiator hoses are also hot. Thus,
>>the thermostat and water pump are known good.
>>
>>No evident leaks of coolant while sitting, unless its started
>>overheating, in which case it comes out of the recovery bottle at the cap.
>>
>>Any ideas, or is it time for the scrapyard? I had the head gasket
>>replaced awhile back, and one mechanic mentioned that they might have
>>blocked a coolant passage, and thoughts on this random thought?
>>
>>Thanks guys!
>>
>>-Kurt

Mike Romain

You are implying you are leaking fluid somewhere?

Otherwise 'refilling' doesn't make sense unless that is just after a
blow over.

So you are getting air somewhere, somehow into it. A waterpump with
almost no blades left can maybe aerate the coolant and put bubbles in.
The bubbles then go and get stuck in the head causing it to overheat.
Unusual, but it can happen.

Did it start doing this after any particular work was done or were all
the parts below in response to the overheating.

Something like the fan clutch comes to mind. They make two that will
fit on that engine. One id reverse of the other. Same for the
waterpump, they make two versions.

I have seen and heard of the wrong pump or clutch being in the 'right'
box too...

The serpentine belt engine uses reverse rotation parts. The V-belt
engine uses the normal parts.

Mike

"Kurt C. Hack" wrote:
>
> I am bleeding the air out by jacking up the rear of the vehicle and
> removing the temp sensor at the back of the motor until all the air
> escapes and only the coolant is flowing.
>
> The temp sender has been replaced and I have checked the value coming
> from it compared to what the gauge states, so the gauge and the temp
> sender is known good.
>
> I have gone through the process of letting the system "right" itself
> after refilling and bleeding the system. After that its OK for the
> first run cycle. However, after letting it cool overnight its starts
> the process again of overheating. The problem becomes progressively
> worse until I refill and bleed the system again.
>
> Thanks,
> -Kurt
>
> Mike Romain wrote:
>
> > I am missing something here.
> >
> > How are you 'bleeding' the air out of the system?
> >
> > Once you have flow to the heater core and the recovery bottle, the air
> > is gone.
> >
> > Are you sure your temperature gauge isn't just bad? They are well known
> > to not be very accurate.
> >
> > Do you have the coolant in the bottle near the bottom of it when cold?
> > If overfilled it will **** out on the ground until it finds it's proper
> > running level to allow for hot expansion.
> >
> > In other words are you sure it's overheating?
> >
> > Mike
> > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> > 88 Cherokee 235 BFG AT's
> >
> > "Kurt C. Hack" wrote:
> >
> >>1987 Cherokee with 4.0L and automatic transmission overheats all the
> >>time. I have replaced the following:
> >> Radiator
> >> Temperature Sending Unit
> >> Thermostat
> >> Thermostat Housing
> >> Heater Core
> >> Recovery Bottle Cap
> >> Fan Clutch
> >> Spark Plugs
> >> Spark Plug Wires
> >> Rotor
> >> Distributor Cap
> >>
> >>I have also had the water pump checked and the coolant checked for
> >>exhaust gasses. Both passed fine.
> >>
> >>I can bleed the air out of the system and it will do fine for one run
> >>cycle. However, when I turn it off and let it cool, the next time I
> >>start it will start the overheating again. The overheating gets
> >>progressively worse with each hot\cold cycle of the engine until I bleed
> >>the air back out of the system.
> >>
> >>I can get heat out of the heater and can see the coolant moving in the
> >>recovery bottle. The upper and lower radiator hoses are also hot. Thus,
> >>the thermostat and water pump are known good.
> >>
> >>No evident leaks of coolant while sitting, unless its started
> >>overheating, in which case it comes out of the recovery bottle at the cap.
> >>
> >>Any ideas, or is it time for the scrapyard? I had the head gasket
> >>replaced awhile back, and one mechanic mentioned that they might have
> >>blocked a coolant passage, and thoughts on this random thought?
> >>
> >>Thanks guys!
> >>
> >>-Kurt