Continued: REPAIR QUESTION: Radiator chronically overheats!!

Q

Quiet Voice

Guest

• Nov 3, 2003

• #1

Greetings all:

I previously posted to these newsgroups concerning a vexing problem I
was having with an engine that crhonically overheats.

A brief recap:
I have a '96 jeep cherokee. Whenever I drive it more than a few miles,
the radiator overheats and boils over. I was told at one garage that
the radiator was bad. Replaced it. Same problem. Another place said
the thermosat was bad. Replaced it, no change. I know the water pump
is good.

Since that time, I've found out a few more wrinkles to the fold.......

To make a long story short, I disovered two things:

1)So long as the heater is on, the engine will NOT boil over....no
matter how far I drive.

2)When I stop at red lights, the heater starts to blow COLD air. It
heats up again as soon as I start driving again.

Ever since I discovered point (1), I have been driving with the heater
on full blast and have not had a problem.....except that it gets
AWFULLY hot inside the car!

I'm curious to know if this additional information will clue anyone in
as to what's going on wrong with this vehicle.

Any and all suggestions appreciatd!!

 

C

Chris Phillipo

Guest

• Nov 3, 2003

• #2

In article <[email protected]>,
[email protected] says...
> Greetings all:
>
> I previously posted to these newsgroups concerning a vexing problem I
> was having with an engine that crhonically overheats.
>
> A brief recap:
> I have a '96 jeep cherokee. Whenever I drive it more than a few miles,
> the radiator overheats and boils over. I was told at one garage that
> the radiator was bad. Replaced it. Same problem. Another place said
> the thermosat was bad. Replaced it, no change. I know the water pump
> is good.
>
> Since that time, I've found out a few more wrinkles to the fold.......
>
> To make a long story short, I disovered two things:
>
> 1)So long as the heater is on, the engine will NOT boil over....no
> matter how far I drive.
>
> 2)When I stop at red lights, the heater starts to blow COLD air. It
> heats up again as soon as I start driving again.
>
> Ever since I discovered point (1), I have been driving with the heater
> on full blast and have not had a problem.....except that it gets
> AWFULLY hot inside the car!
>
> I'm curious to know if this additional information will clue anyone in
> as to what's going on wrong with this vehicle.
>
> Any and all suggestions appreciatd!!
>


You are sure the water pump is good? Sounds like at idle no hot water
is getting to your heater core.
--
____________________
Remove "X" from email address to reply.

 

A

AZGuy

Guest

• Nov 3, 2003

• #3

On 2 Nov 2003 20:24:23 -0800, [email protected] (Quiet
Voice) wrote:

>Greetings all:
>
>I previously posted to these newsgroups concerning a vexing problem I
>was having with an engine that crhonically overheats.
>
>A brief recap:
>I have a '96 jeep cherokee. Whenever I drive it more than a few miles,
>the radiator overheats and boils over. I was told at one garage that
>the radiator was bad. Replaced it. Same problem. Another place said
>the thermosat was bad. Replaced it, no change. I know the water pump
>is good.
>
>Since that time, I've found out a few more wrinkles to the fold.......
>
>To make a long story short, I disovered two things:
>
>1)So long as the heater is on, the engine will NOT boil over....no
>matter how far I drive.
>
>2)When I stop at red lights, the heater starts to blow COLD air. It
>heats up again as soon as I start driving again.
>
>Ever since I discovered point (1), I have been driving with the heater
>on full blast and have not had a problem.....except that it gets
>AWFULLY hot inside the car!
>
>I'm curious to know if this additional information will clue anyone in
>as to what's going on wrong with this vehicle.
>
>Any and all suggestions appreciatd!!

Are you sure all the air is burped out of that thing? And what makes
you sure the water pump is good? The impeller could be eaten away.

 

M

MaxAluminum

Guest

• Nov 3, 2003

• #4

AZGuy <[email protected]> wrote in message news:<[email protected]>...
> On 2 Nov 2003 20:24:23 -0800, [email protected] (Quiet
> Voice) wrote:
>
> >Greetings all:
> >
> >I previously posted to these newsgroups concerning a vexing problem I
> >was having with an engine that crhonically overheats.
> >
> >A brief recap:
> >I have a '96 jeep cherokee. Whenever I drive it more than a few miles,
> >the radiator overheats and boils over. I was told at one garage that
> >the radiator was bad. Replaced it. Same problem. Another place said
> >the thermosat was bad. Replaced it, no change. I know the water pump
> >is good.
> >
> >Since that time, I've found out a few more wrinkles to the fold.......
> >
> >To make a long story short, I disovered two things:
> >
> >1)So long as the heater is on, the engine will NOT boil over....no
> >matter how far I drive.
> >
> >2)When I stop at red lights, the heater starts to blow COLD air. It
> >heats up again as soon as I start driving again.
> >
> >Ever since I discovered point (1), I have been driving with the heater
> >on full blast and have not had a problem.....except that it gets
> >AWFULLY hot inside the car!
> >
> >I'm curious to know if this additional information will clue anyone in
> >as to what's going on wrong with this vehicle.
> >
> >Any and all suggestions appreciatd!!
>
> Are you sure all the air is burped out of that thing? And what makes
> you sure the water pump is good? The impeller could be eaten away.

If your heater starts blowing cold, you DO have air in the system I
think. The theory of the bad water pump impeller has merit as well.

 

Q

Quiet Voice

Guest

• Nov 3, 2003

• #5

Hi,

Thanks for the response....


AZGuy <[email protected]> wrote:

> Are you sure all the air is burped out of that thing? And what makes
> you sure the water pump is good? The impeller could be eaten away.

No, I'm not sure about the air. Others have mentiont that. I would
have assumed that they would have done that when they replaced the
radiator...but I can't say for sure. Is that something I can do
myself?

As for the water pump, I had it replaced very recently. Plus, if it
weren't working, wouldn't it mean that I'd *never* get hot air out of
the heater (because no water would circulate)?

Thnx!

 

R

Roger Brown

Guest

• Nov 3, 2003

• #6

Quiet Voice wrote:
>
> Hi,
>
> Thanks for the response....
>
> AZGuy <[email protected]> wrote:
>
> > Are you sure all the air is burped out of that thing? And what makes
> > you sure the water pump is good? The impeller could be eaten away.
>
> No, I'm not sure about the air. Others have mentiont that. I would
> have assumed that they would have done that when they replaced the
> radiator...but I can't say for sure. Is that something I can do
> myself?
>
> As for the water pump, I had it replaced very recently. Plus, if it
> weren't working, wouldn't it mean that I'd *never* get hot air out of
> the heater (because no water would circulate)?

You minght consider having the cooling system pressure tested and/or haved the coolant tested for the presence of exhaust gas to
see if you are getting an exhaust gas leak into the cooling system. When I've had head gasket leaks in my engine, one of the
first signs I've had was lack of heater output, due to the exhaust gas filling the top of the cooling system. Would also hear a
gurgling sound out of the heater core when the engine was reved.

It also may be trapped air as mentioned above, try running the engine with the radiator cap off until the t-stat opens and see
if the air will be released.

--
Roger

 

M

Mike Romain

Guest

• Nov 3, 2003

• #7

Blowing cold when idling means you either have an air lock in the
cooling system or the wrong waterpump in it.

They make 2 waterpumps for that engine. I have seen them mixed up in
the box.

One is a normal rotation pump for the V-belt version and the other is a
reverse rotation pump for the serpentine belt.

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

Quiet Voice wrote:
>
> Greetings all:
>
> I previously posted to these newsgroups concerning a vexing problem I
> was having with an engine that crhonically overheats.
>
> A brief recap:
> I have a '96 jeep cherokee. Whenever I drive it more than a few miles,
> the radiator overheats and boils over. I was told at one garage that
> the radiator was bad. Replaced it. Same problem. Another place said
> the thermosat was bad. Replaced it, no change. I know the water pump
> is good.
>
> Since that time, I've found out a few more wrinkles to the fold.......
>
> To make a long story short, I disovered two things:
>
> 1)So long as the heater is on, the engine will NOT boil over....no
> matter how far I drive.
>
> 2)When I stop at red lights, the heater starts to blow COLD air. It
> heats up again as soon as I start driving again.
>
> Ever since I discovered point (1), I have been driving with the heater
> on full blast and have not had a problem.....except that it gets
> AWFULLY hot inside the car!
>
> I'm curious to know if this additional information will clue anyone in
> as to what's going on wrong with this vehicle.
>
> Any and all suggestions appreciatd!!

 

W

Will Honea

Guest

• Nov 3, 2003

• #8

On Mon, 3 Nov 2003 04:24:23 UTC [email protected] (Quiet
Voice) wrote:

> Greetings all:
>
> I previously posted to these newsgroups concerning a vexing problem I
> was having with an engine that crhonically overheats.
>
> A brief recap:
> I have a '96 jeep cherokee. Whenever I drive it more than a few miles,
> the radiator overheats and boils over. I was told at one garage that
> the radiator was bad. Replaced it. Same problem. Another place said
> the thermosat was bad. Replaced it, no change. I know the water pump
> is good.
>
> Since that time, I've found out a few more wrinkles to the fold.......
>
> To make a long story short, I disovered two things:
>
> 1)So long as the heater is on, the engine will NOT boil over....no
> matter how far I drive.
>
> 2)When I stop at red lights, the heater starts to blow COLD air. It
> heats up again as soon as I start driving again.
>
> Ever since I discovered point (1), I have been driving with the heater
> on full blast and have not had a problem.....except that it gets
> AWFULLY hot inside the car!
>
> I'm curious to know if this additional information will clue anyone in
> as to what's going on wrong with this vehicle.
>
> Any and all suggestions appreciatd!!

Did you replace the hoses as well? Could be a collapsed lower
radiator hose.

--
Will Honea <[email protected]>

 

C

calebs67

Guest

• Nov 3, 2003

• #9

your heater core is a lot like a little radiator, whenever your heat
is on the motor usually runs cooler. and a lot of cars have vacume
operated heaters, when your siting a stop lights the motor is ideling
and not producing enough vacume to turn it on, so the blower fan is
just pumping air from outside air. make shure you have the right water
pump and make shure its turning the right direction. and if you havent
flushed your coolant, that couldent hurt.

 

M

MaxAluminum

Guest

• Nov 3, 2003

• #10

Mike Romain <[email protected]> wrote in message news:<[email protected]>...
> Blowing cold when idling means you either have an air lock in the
> cooling system or the wrong waterpump in it.
>
> They make 2 waterpumps for that engine. I have seen them mixed up in
> the box.
>
> One is a normal rotation pump for the V-belt version and the other is a
> reverse rotation pump for the serpentine belt.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> Quiet Voice wrote:
> >
> > Greetings all:
> >
> > I previously posted to these newsgroups concerning a vexing problem I
> > was having with an engine that crhonically overheats.
> >
> > A brief recap:
> > I have a '96 jeep cherokee. Whenever I drive it more than a few miles,
> > the radiator overheats and boils over. I was told at one garage that
> > the radiator was bad. Replaced it. Same problem. Another place said
> > the thermosat was bad. Replaced it, no change. I know the water pump
> > is good.
> >
> > Since that time, I've found out a few more wrinkles to the fold.......
> >
> > To make a long story short, I disovered two things:
> >
> > 1)So long as the heater is on, the engine will NOT boil over....no
> > matter how far I drive.
> >
> > 2)When I stop at red lights, the heater starts to blow COLD air. It
> > heats up again as soon as I start driving again.
> >
> > Ever since I discovered point (1), I have been driving with the heater
> > on full blast and have not had a problem.....except that it gets
> > AWFULLY hot inside the car!
> >
> > I'm curious to know if this additional information will clue anyone in
> > as to what's going on wrong with this vehicle.
> >
> > Any and all suggestions appreciatd!!

He didn't say that the problem happened right after installing the new
water pump. If so, Mike, your answer is beautiful. But if he had the
pump changed because of the problem, maybe he's been chronically low
on water for some time, suggesting he's losing coolant. The pressure
test is a good idea right off. And is he checking the coolant? Adding?
This can't be diagnosed from the driver's seat. And lastly, circulate
that air bubble long enough and you will blow a head gasket if not
done already.

 

L

Lon Stowell

Guest

• Nov 4, 2003

• #11

Approximately 11/3/03 06:44, Quiet Voice uttered for posterity:

> Hi,
>
> Thanks for the response....
>
>
> AZGuy <[email protected]> wrote:
>
>> Are you sure all the air is burped out of that thing? And what makes
>> you sure the water pump is good? The impeller could be eaten away.
>
> No, I'm not sure about the air. Others have mentiont that. I would
> have assumed that they would have done that when they replaced the
> radiator...but I can't say for sure. Is that something I can do
> myself?
>
> As for the water pump, I had it replaced very recently. Plus, if it
> weren't working, wouldn't it mean that I'd *never* get hot air out of
> the heater (because no water would circulate)?

Neither presumption is warranted. When the radiator is replaced,
air bubbles in the engine can happen and are a pig to get rid of.
As for the water pump, if it can only pump enough water at high
rpm, you'd get cold air at low speed.

Actually, I wonder if they installed the wrong water pump, and
the impeller is being spun backwards. Since it is just centrifugal,
I could be convinced that it might actually push a *little* water
at high rpm when run backwards...

Nothing other than a water pump flow test is good enough to prove
or disprove that it is the cause.

--
My governor can kick your governor's ass

 

C

Chris Phillipo

Guest

• Nov 4, 2003

• #12

In article <[email protected]>,
[email protected] says...
> Hi,
>
> Thanks for the response....
>
>
> AZGuy <[email protected]> wrote:
>
> > Are you sure all the air is burped out of that thing? And what makes
> > you sure the water pump is good? The impeller could be eaten away.
>
> No, I'm not sure about the air. Others have mentiont that. I would
> have assumed that they would have done that when they replaced the
> radiator...but I can't say for sure. Is that something I can do
> myself?
>
> As for the water pump, I had it replaced very recently. Plus, if it
> weren't working, wouldn't it mean that I'd *never* get hot air out of
> the heater (because no water would circulate)?
>
> Thnx!
>

If the impeller is corroded it would move water at higher rpms but maybe
not at idle. A new pump should have a good impeller on it though.
--
____________________
Remove "X" from email address to reply.

 

W

Will Honea

Guest

• Nov 4, 2003

• #13

Strange engine you have there. The only time I get a vacuum higher
than at idle is when I'm using engine braking with the throttle closed
or for the short period after I close the throttle during a shift.

Sounds like a developing consensis that it's a pump issue.

On Mon, 3 Nov 2003 23:29:18 UTC [email protected] (calebs67) wrote:

> your heater core is a lot like a little radiator, whenever your heat
> is on the motor usually runs cooler. and a lot of cars have vacume
> operated heaters, when your siting a stop lights the motor is ideling
> and not producing enough vacume to turn it on, so the blower fan is
> just pumping air from outside air. make shure you have the right water
> pump and make shure its turning the right direction. and if you havent
> flushed your coolant, that couldent hurt.


--
Will Honea <[email protected]>

 

P

Paul Elliot

Guest

• Nov 30, 2003

• #14

Even with a new waterpump, you can have low flow at idle or low speed due to
a poorly designed or made impeller. There are many substandard aftermarket
pump out there, so if it was a cheapie, look at buying a better pump.
HTH
Paul E.

--
"I'd rather have a bottle in front of me than a frontal lobotomy."

"Quiet Voice" <[email protected]> wrote in message
news:[email protected]...
> Hi,
>
> Thanks for the response....
>
>
> AZGuy <[email protected]> wrote:
>
> > Are you sure all the air is burped out of that thing? And what makes
> > you sure the water pump is good? The impeller could be eaten away.
>
> No, I'm not sure about the air. Others have mentiont that. I would
> have assumed that they would have done that when they replaced the
> radiator...but I can't say for sure. Is that something I can do
> myself?
>
> As for the water pump, I had it replaced very recently. Plus, if it
> weren't working, wouldn't it mean that I'd *never* get hot air out of
> the heater (because no water would circulate)?
>
> Thnx!
>