2000 JGC V-8 overheating/ occasionally only !!
 

I posted here about this before, and got some good info.

Symptoms again.......... the car never overheats in town. Does not
overheat sitting at a redlight.

On the highway, at 70 mph or so, the engine runs about 10-15 degrees
over what it normally does. Normally, it runs between 190-200 degrees, and
now runs from 200 to 215 degrees. (Some will say this is normal. Maybe,
but not for my car. First 120K miles, it ran cooler).


At times, if I go up a long, steep grade, it will overheat rapidly, up to
250-260..... it has not been boiling over. If a long steep grade is 2
miles long, it will heat up like this, and then after the road levels off,
the engine will cool down to 210 degrees after 2 or 3 miles.

Here is the funny part............ it will not do this every time I go up a
steep grade. I can do the same grade two times in one day..... same outside
temperature, and one trip it will run 210 degrees up the hill and on the
second trip it will almost boil over. So, it is not consistent.

Here is what I have done. New thermostat, 190 degrees. New coolant, and
flushed radiator. One year ago installed new fan clutch. New serpentine
drive belt (fan belt)

Jeep has original water pump and radiator. Mileage is 130K. Engine is
fine.

I am not a mechanic, but I think there are just two main things left. I
think the water flow is restricted by a clogged or bad radiator, OR I have
a defect in the water pump.

Questions: How can I diagnose the most probable culprit. the water pump
or the radiator?

Can't radiator shops do a flow test on the radiator ? Would that test
also give a hint about the operation of the water pump ?

Are there other possible mechanical problems other than the water pump and
radiator, given the steps that I have taken already to cure this problem ?

If you had to guess , would you vote for a new water pump or a rod-job or
new radiator?

Remember two things...... the car NEVER overheats at idle or at slow speed.
It only overheats at higher speeds, going up steep hills. And, the
overheating is erratic. The very same conditions/ temp/ road grade/ etc
will not give the same result each time.

Whaddduuuyaaaa think ??


Thanks !!

--james--

Re: 2000 JGC V-8 overheating/ occasionally only !!
 

Hi James,
I would replace the thermostat, again, I've found many bad ones,
especially from Pep Boys. Make sure the radiator caps is holding at
least fifteen pounds to prevent the bottom hose from collapsing via a
clogged radiator.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/

James wrote:
>
> I posted here about this before, and got some good info.
>
> Symptoms again.......... the car never overheats in town. Does not
> overheat sitting at a redlight.
>
> On the highway, at 70 mph or so, the engine runs about 10-15 degrees
> over what it normally does. Normally, it runs between 190-200 degrees, and
> now runs from 200 to 215 degrees. (Some will say this is normal. Maybe,
> but not for my car. First 120K miles, it ran cooler).
>
> At times, if I go up a long, steep grade, it will overheat rapidly, up to
> 250-260..... it has not been boiling over. If a long steep grade is 2
> miles long, it will heat up like this, and then after the road levels off,
> the engine will cool down to 210 degrees after 2 or 3 miles.
>
> Here is the funny part............ it will not do this every time I go up a
> steep grade. I can do the same grade two times in one day..... same outside
> temperature, and one trip it will run 210 degrees up the hill and on the
> second trip it will almost boil over. So, it is not consistent.
>
> Here is what I have done. New thermostat, 190 degrees. New coolant, and
> flushed radiator. One year ago installed new fan clutch. New serpentine
> drive belt (fan belt)
>
> Jeep has original water pump and radiator. Mileage is 130K. Engine is
> fine.
>
> I am not a mechanic, but I think there are just two main things left. I
> think the water flow is restricted by a clogged or bad radiator, OR I have
> a defect in the water pump.
>
> Questions: How can I diagnose the most probable culprit. the water pump
> or the radiator?
>
> Can't radiator shops do a flow test on the radiator ? Would that test
> also give a hint about the operation of the water pump ?
>
> Are there other possible mechanical problems other than the water pump and
> radiator, given the steps that I have taken already to cure this problem ?
>
> If you had to guess , would you vote for a new water pump or a rod-job or
> new radiator?
>
> Remember two things...... the car NEVER overheats at idle or at slow speed.
> It only overheats at higher speeds, going up steep hills. And, the
> overheating is erratic. The very same conditions/ temp/ road grade/ etc
> will not give the same result each time.
>
> Whaddduuuyaaaa think ??
>
> Thanks !!
>
> --james--

Re: 2000 JGC V-8 overheating/ occasionally only !!
 

Hi James,
I would replace the thermostat, again, I've found many bad ones,
especially from Pep Boys. Make sure the radiator caps is holding at
least fifteen pounds to prevent the bottom hose from collapsing via a
clogged radiator.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/

James wrote:
>
> I posted here about this before, and got some good info.
>
> Symptoms again.......... the car never overheats in town. Does not
> overheat sitting at a redlight.
>
> On the highway, at 70 mph or so, the engine runs about 10-15 degrees
> over what it normally does. Normally, it runs between 190-200 degrees, and
> now runs from 200 to 215 degrees. (Some will say this is normal. Maybe,
> but not for my car. First 120K miles, it ran cooler).
>
> At times, if I go up a long, steep grade, it will overheat rapidly, up to
> 250-260..... it has not been boiling over. If a long steep grade is 2
> miles long, it will heat up like this, and then after the road levels off,
> the engine will cool down to 210 degrees after 2 or 3 miles.
>
> Here is the funny part............ it will not do this every time I go up a
> steep grade. I can do the same grade two times in one day..... same outside
> temperature, and one trip it will run 210 degrees up the hill and on the
> second trip it will almost boil over. So, it is not consistent.
>
> Here is what I have done. New thermostat, 190 degrees. New coolant, and
> flushed radiator. One year ago installed new fan clutch. New serpentine
> drive belt (fan belt)
>
> Jeep has original water pump and radiator. Mileage is 130K. Engine is
> fine.
>
> I am not a mechanic, but I think there are just two main things left. I
> think the water flow is restricted by a clogged or bad radiator, OR I have
> a defect in the water pump.
>
> Questions: How can I diagnose the most probable culprit. the water pump
> or the radiator?
>
> Can't radiator shops do a flow test on the radiator ? Would that test
> also give a hint about the operation of the water pump ?
>
> Are there other possible mechanical problems other than the water pump and
> radiator, given the steps that I have taken already to cure this problem ?
>
> If you had to guess , would you vote for a new water pump or a rod-job or
> new radiator?
>
> Remember two things...... the car NEVER overheats at idle or at slow speed.
> It only overheats at higher speeds, going up steep hills. And, the
> overheating is erratic. The very same conditions/ temp/ road grade/ etc
> will not give the same result each time.
>
> Whaddduuuyaaaa think ??
>
> Thanks !!
>
> --james--

Re: 2000 JGC V-8 overheating/ occasionally only !!
 

Hi James,
I would replace the thermostat, again, I've found many bad ones,
especially from Pep Boys. Make sure the radiator caps is holding at
least fifteen pounds to prevent the bottom hose from collapsing via a
clogged radiator.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/

James wrote:
>
> I posted here about this before, and got some good info.
>
> Symptoms again.......... the car never overheats in town. Does not
> overheat sitting at a redlight.
>
> On the highway, at 70 mph or so, the engine runs about 10-15 degrees
> over what it normally does. Normally, it runs between 190-200 degrees, and
> now runs from 200 to 215 degrees. (Some will say this is normal. Maybe,
> but not for my car. First 120K miles, it ran cooler).
>
> At times, if I go up a long, steep grade, it will overheat rapidly, up to
> 250-260..... it has not been boiling over. If a long steep grade is 2
> miles long, it will heat up like this, and then after the road levels off,
> the engine will cool down to 210 degrees after 2 or 3 miles.
>
> Here is the funny part............ it will not do this every time I go up a
> steep grade. I can do the same grade two times in one day..... same outside
> temperature, and one trip it will run 210 degrees up the hill and on the
> second trip it will almost boil over. So, it is not consistent.
>
> Here is what I have done. New thermostat, 190 degrees. New coolant, and
> flushed radiator. One year ago installed new fan clutch. New serpentine
> drive belt (fan belt)
>
> Jeep has original water pump and radiator. Mileage is 130K. Engine is
> fine.
>
> I am not a mechanic, but I think there are just two main things left. I
> think the water flow is restricted by a clogged or bad radiator, OR I have
> a defect in the water pump.
>
> Questions: How can I diagnose the most probable culprit. the water pump
> or the radiator?
>
> Can't radiator shops do a flow test on the radiator ? Would that test
> also give a hint about the operation of the water pump ?
>
> Are there other possible mechanical problems other than the water pump and
> radiator, given the steps that I have taken already to cure this problem ?
>
> If you had to guess , would you vote for a new water pump or a rod-job or
> new radiator?
>
> Remember two things...... the car NEVER overheats at idle or at slow speed.
> It only overheats at higher speeds, going up steep hills. And, the
> overheating is erratic. The very same conditions/ temp/ road grade/ etc
> will not give the same result each time.
>
> Whaddduuuyaaaa think ??
>
> Thanks !!
>
> --james--

Re: 2000 JGC V-8 overheating/ occasionally only !!
 

Bill, do you think the thermostat only malfunctions when going up a steep
grade ??

I had thought about the radiator cap and took it off today and looked it
over. It "looked" fine, and the rubber gasket looked fine.


How can one test for 15 lbs ?? Or, as a general rule, how can I know if
the radiator cap is ok ?? Can that part only be bought from Jeep ?

--James--

Re: 2000 JGC V-8 overheating/ occasionally only !!
 

Bill, do you think the thermostat only malfunctions when going up a steep
grade ??

I had thought about the radiator cap and took it off today and looked it
over. It "looked" fine, and the rubber gasket looked fine.


How can one test for 15 lbs ?? Or, as a general rule, how can I know if
the radiator cap is ok ?? Can that part only be bought from Jeep ?

--James--

Re: 2000 JGC V-8 overheating/ occasionally only !!
 

Bill, do you think the thermostat only malfunctions when going up a steep
grade ??

I had thought about the radiator cap and took it off today and looked it
over. It "looked" fine, and the rubber gasket looked fine.


How can one test for 15 lbs ?? Or, as a general rule, how can I know if
the radiator cap is ok ?? Can that part only be bought from Jeep ?

--James--

Re: 2000 JGC V-8 overheating/ occasionally only !!
 

Hi James,
Many thermostats fail or jam half open, also giving you a much
longer time to reach operating temperature, if at all.
I go by the feel of the top radiator hose, but I'll bet any parts
store would pressure test yours.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/

James wrote:
>
> Bill, do you think the thermostat only malfunctions when going up a steep
> grade ??
>
> I had thought about the radiator cap and took it off today and looked it
> over. It "looked" fine, and the rubber gasket looked fine.
>
> How can one test for 15 lbs ?? Or, as a general rule, how can I know if
> the radiator cap is ok ?? Can that part only be bought from Jeep ?
>
> --James--

Re: 2000 JGC V-8 overheating/ occasionally only !!
 

Hi James,
Many thermostats fail or jam half open, also giving you a much
longer time to reach operating temperature, if at all.
I go by the feel of the top radiator hose, but I'll bet any parts
store would pressure test yours.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/

James wrote:
>
> Bill, do you think the thermostat only malfunctions when going up a steep
> grade ??
>
> I had thought about the radiator cap and took it off today and looked it
> over. It "looked" fine, and the rubber gasket looked fine.
>
> How can one test for 15 lbs ?? Or, as a general rule, how can I know if
> the radiator cap is ok ?? Can that part only be bought from Jeep ?
>
> --James--

Re: 2000 JGC V-8 overheating/ occasionally only !!
 

Hi James,
Many thermostats fail or jam half open, also giving you a much
longer time to reach operating temperature, if at all.
I go by the feel of the top radiator hose, but I'll bet any parts
store would pressure test yours.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/

James wrote:
>
> Bill, do you think the thermostat only malfunctions when going up a steep
> grade ??
>
> I had thought about the radiator cap and took it off today and looked it
> over. It "looked" fine, and the rubber gasket looked fine.
>
> How can one test for 15 lbs ?? Or, as a general rule, how can I know if
> the radiator cap is ok ?? Can that part only be bought from Jeep ?
>
> --James--