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

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).

Are you sure the temperature sender is working properly?

Next time your overheating, turn on the inside heater on full
blast and watch what happens to the temperature.

The pump can be wearing, but that's not usual. A clogged radiator
is alway a possibility. Basically you just drain it, and look inside.

I just replaced my radiator after it sprang a small leak. Didn't look
that bad but there was some buildup. Not bad for a 1993 ZJ.

--
DougW

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

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).

Are you sure the temperature sender is working properly?

Next time your overheating, turn on the inside heater on full
blast and watch what happens to the temperature.

The pump can be wearing, but that's not usual. A clogged radiator
is alway a possibility. Basically you just drain it, and look inside.

I just replaced my radiator after it sprang a small leak. Didn't look
that bad but there was some buildup. Not bad for a 1993 ZJ.

--
DougW

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

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).

Are you sure the temperature sender is working properly?

Next time your overheating, turn on the inside heater on full
blast and watch what happens to the temperature.

The pump can be wearing, but that's not usual. A clogged radiator
is alway a possibility. Basically you just drain it, and look inside.

I just replaced my radiator after it sprang a small leak. Didn't look
that bad but there was some buildup. Not bad for a 1993 ZJ.

--
DougW

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

On Sat, 16 Dec 2006 21:10:26 -0500, "James" <no one@bellsouth.com>
wrote:

>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 ??

My nickle is on the clutch fan. I know it was replaced 1 year ago but
I strongly suspect that is is the culprit here. Its engagement temp is
too high and thats why sometimes it cools and sometimes not. Ram air a
lone will not always cool the engine especailly a V8 in a GC because
it is a tight fit. At the link below you will find instruction on have
to tweak the adjustment of a clutch fan because most of the time a
little twaeking will cure them.

http://forum.snoman.com/viewtopic.php?t=79
-----------------
TheSnoMan.com

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

On Sat, 16 Dec 2006 21:10:26 -0500, "James" <no one@bellsouth.com>
wrote:

>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 ??

My nickle is on the clutch fan. I know it was replaced 1 year ago but
I strongly suspect that is is the culprit here. Its engagement temp is
too high and thats why sometimes it cools and sometimes not. Ram air a
lone will not always cool the engine especailly a V8 in a GC because
it is a tight fit. At the link below you will find instruction on have
to tweak the adjustment of a clutch fan because most of the time a
little twaeking will cure them.

http://forum.snoman.com/viewtopic.php?t=79
-----------------
TheSnoMan.com

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

On Sat, 16 Dec 2006 21:10:26 -0500, "James" <no one@bellsouth.com>
wrote:

>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 ??

My nickle is on the clutch fan. I know it was replaced 1 year ago but
I strongly suspect that is is the culprit here. Its engagement temp is
too high and thats why sometimes it cools and sometimes not. Ram air a
lone will not always cool the engine especailly a V8 in a GC because
it is a tight fit. At the link below you will find instruction on have
to tweak the adjustment of a clutch fan because most of the time a
little twaeking will cure them.

http://forum.snoman.com/viewtopic.php?t=79
-----------------
TheSnoMan.com

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

Sno man, I had been under the impression that a problem with the clutch fan
would make a car overheat at idle and slow speeds, such as when stopped at a
red light. Maybe I am thinking about the electric fan though..........

I didn't know they could be adjusted. I will study the site.

Thanks !!

--James--

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

Sno man, I had been under the impression that a problem with the clutch fan
would make a car overheat at idle and slow speeds, such as when stopped at a
red light. Maybe I am thinking about the electric fan though..........

I didn't know they could be adjusted. I will study the site.

Thanks !!

--James--

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

Sno man, I had been under the impression that a problem with the clutch fan
would make a car overheat at idle and slow speeds, such as when stopped at a
red light. Maybe I am thinking about the electric fan though..........

I didn't know they could be adjusted. I will study the site.

Thanks !!

--James--

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

On Sun, 17 Dec 2006 08:30:03 -0500, "James" <no one@bellsouth.com>
wrote:

>Sno man, I had been under the impression that a problem with the clutch fan
>would make a car overheat at idle and slow speeds, such as when stopped at a
>red light. Maybe I am thinking about the electric fan though..........
>
>I didn't know they could be adjusted. I will study the site.
>
>Thanks !!
>
>--James--
>

A clutch fan is centrifical and bimetal thermostat controlled. It
engages when the bimetal control lets fluid into clutch disc area
faster than centrifical force can remove it. This is why it can
sometimes cool better at low speed because the centrifical forces are
not purging fluid from it faster than it is being replaced. Also at
low speeds the engine is making less power on average and needs less
cooling generally. When you put a big V8 in a small car the cooling
system has to be just right for it to keep its cool. I would consider
a electric fan as a last resort because it cannot come close to
matching the air flow capabilies of a engine driven clutch fan. To do
so would require more electric power than you vehicle can produce to
sustain it.
-----------------
TheSnoMan.com