88 Jeep Comanche cooling issues
 

So we had a really hot day here awhile ago, and I ended up overheating my
Jeep Comanche (4.0l engine). I had problems before, but nothing like that.
Stuck in stop and go traffic, hot temps, etc.

So I'm trying to do a little diagnosis, but I'm not that automotively
inclined. But what I'm seeing if very little coolant flow when the Jeep is
idling. I have no way of measuring it, but it seems to just be trickling
into the tank. When I had my helper/wife rev it up to 2000 rpm, it flowed
much faster, but still not a torrent or anything.

Is it possible that the water pump has gone caput, even though it's not
locked up or anything? Should I start with just replacing that?

Thanks in advance. This group has been a great asset in the past.

Clint

Re: 88 Jeep Comanche cooling issues
 

Clint wrote:
> So we had a really hot day here awhile ago, and I ended up
> overheating my Jeep Comanche (4.0l engine). I had problems before,
> but nothing like that. Stuck in stop and go traffic, hot temps, etc.
>
> So I'm trying to do a little diagnosis, but I'm not that automotively
> inclined. But what I'm seeing if very little coolant flow when the
> Jeep is idling. I have no way of measuring it, but it seems to just
> be trickling into the tank. When I had my helper/wife rev it up to
> 2000 rpm, it flowed much faster, but still not a torrent or anything.
>
> Is it possible that the water pump has gone caput, even though it's
> not locked up or anything? Should I start with just replacing that?

Very possible the vanes have gone. It's also possible your radiator
is clogged. Is there a lot of buildup in it?

Keep in mind coolant flow when cold will be slow. That's the job
of the thermostat valve. Full flow will only happen when the engine
is at operating temperature. Needless to say the system is under
pressure at that point and removing the radiator cap to look will
get you seriously burned.

--
DougW

Re: 88 Jeep Comanche cooling issues
 

Clint wrote:
> So we had a really hot day here awhile ago, and I ended up
> overheating my Jeep Comanche (4.0l engine). I had problems before,
> but nothing like that. Stuck in stop and go traffic, hot temps, etc.
>
> So I'm trying to do a little diagnosis, but I'm not that automotively
> inclined. But what I'm seeing if very little coolant flow when the
> Jeep is idling. I have no way of measuring it, but it seems to just
> be trickling into the tank. When I had my helper/wife rev it up to
> 2000 rpm, it flowed much faster, but still not a torrent or anything.
>
> Is it possible that the water pump has gone caput, even though it's
> not locked up or anything? Should I start with just replacing that?

Very possible the vanes have gone. It's also possible your radiator
is clogged. Is there a lot of buildup in it?

Keep in mind coolant flow when cold will be slow. That's the job
of the thermostat valve. Full flow will only happen when the engine
is at operating temperature. Needless to say the system is under
pressure at that point and removing the radiator cap to look will
get you seriously burned.

--
DougW

Re: 88 Jeep Comanche cooling issues
 

Clint wrote:
> So we had a really hot day here awhile ago, and I ended up
> overheating my Jeep Comanche (4.0l engine). I had problems before,
> but nothing like that. Stuck in stop and go traffic, hot temps, etc.
>
> So I'm trying to do a little diagnosis, but I'm not that automotively
> inclined. But what I'm seeing if very little coolant flow when the
> Jeep is idling. I have no way of measuring it, but it seems to just
> be trickling into the tank. When I had my helper/wife rev it up to
> 2000 rpm, it flowed much faster, but still not a torrent or anything.
>
> Is it possible that the water pump has gone caput, even though it's
> not locked up or anything? Should I start with just replacing that?

Very possible the vanes have gone. It's also possible your radiator
is clogged. Is there a lot of buildup in it?

Keep in mind coolant flow when cold will be slow. That's the job
of the thermostat valve. Full flow will only happen when the engine
is at operating temperature. Needless to say the system is under
pressure at that point and removing the radiator cap to look will
get you seriously burned.

--
DougW

Re: 88 Jeep Comanche cooling issues
 

Where are you watching the coolant flow? My 88 MJ has that @#$% closed
system so I don't really see the flow at the bottle (which is under
pressure with no cap on the radiator to watch - it's on the bottle).

Have you drained the system lately? If so, it's possible to get an air
block in the hose between the reservoir and the thermostat housing.
That will over heat it in a hurry. This happens on refill it the hose
is higher than the bottom of the reservoir.

How about a/c? Mine started running warm in traffic this summer and it
turned out to be a diode in the module that connects to the coil of
the fan relay - it uses steering diodes to merge the radiator tank
sensor and the a/c switch for the electric fan. Fifty cent 1n4000
diode will cure that one - or get two and replqce both just to be
sure. Of course, the electric fan may only mask the problem as mine
ran all summer in West Texas a year or so back with the electric fan
unplugged...

Sounds like either a water pump or a sticking thermostat. Either one
will cause the problem you describe.

On Tue, 19 Sep 2006 02:36:01 UTC "DougW"
<post.replies@invalid.address> wrote:

> Clint wrote:
> > So we had a really hot day here awhile ago, and I ended up
> > overheating my Jeep Comanche (4.0l engine). I had problems before,
> > but nothing like that. Stuck in stop and go traffic, hot temps, etc.
> >
> > So I'm trying to do a little diagnosis, but I'm not that automotively
> > inclined. But what I'm seeing if very little coolant flow when the
> > Jeep is idling. I have no way of measuring it, but it seems to just
> > be trickling into the tank. When I had my helper/wife rev it up to
> > 2000 rpm, it flowed much faster, but still not a torrent or anything.
> >
> > Is it possible that the water pump has gone caput, even though it's
> > not locked up or anything? Should I start with just replacing that?
>
> Very possible the vanes have gone. It's also possible your radiator
> is clogged. Is there a lot of buildup in it?
>
> Keep in mind coolant flow when cold will be slow. That's the job
> of the thermostat valve. Full flow will only happen when the engine
> is at operating temperature. Needless to say the system is under
> pressure at that point and removing the radiator cap to look will
> get you seriously burned.
>


--
Will Honea

Re: 88 Jeep Comanche cooling issues
 

Where are you watching the coolant flow? My 88 MJ has that @#$% closed
system so I don't really see the flow at the bottle (which is under
pressure with no cap on the radiator to watch - it's on the bottle).

Have you drained the system lately? If so, it's possible to get an air
block in the hose between the reservoir and the thermostat housing.
That will over heat it in a hurry. This happens on refill it the hose
is higher than the bottom of the reservoir.

How about a/c? Mine started running warm in traffic this summer and it
turned out to be a diode in the module that connects to the coil of
the fan relay - it uses steering diodes to merge the radiator tank
sensor and the a/c switch for the electric fan. Fifty cent 1n4000
diode will cure that one - or get two and replqce both just to be
sure. Of course, the electric fan may only mask the problem as mine
ran all summer in West Texas a year or so back with the electric fan
unplugged...

Sounds like either a water pump or a sticking thermostat. Either one
will cause the problem you describe.

On Tue, 19 Sep 2006 02:36:01 UTC "DougW"
<post.replies@invalid.address> wrote:

> Clint wrote:
> > So we had a really hot day here awhile ago, and I ended up
> > overheating my Jeep Comanche (4.0l engine). I had problems before,
> > but nothing like that. Stuck in stop and go traffic, hot temps, etc.
> >
> > So I'm trying to do a little diagnosis, but I'm not that automotively
> > inclined. But what I'm seeing if very little coolant flow when the
> > Jeep is idling. I have no way of measuring it, but it seems to just
> > be trickling into the tank. When I had my helper/wife rev it up to
> > 2000 rpm, it flowed much faster, but still not a torrent or anything.
> >
> > Is it possible that the water pump has gone caput, even though it's
> > not locked up or anything? Should I start with just replacing that?
>
> Very possible the vanes have gone. It's also possible your radiator
> is clogged. Is there a lot of buildup in it?
>
> Keep in mind coolant flow when cold will be slow. That's the job
> of the thermostat valve. Full flow will only happen when the engine
> is at operating temperature. Needless to say the system is under
> pressure at that point and removing the radiator cap to look will
> get you seriously burned.
>


--
Will Honea

Re: 88 Jeep Comanche cooling issues
 

Where are you watching the coolant flow? My 88 MJ has that @#$% closed
system so I don't really see the flow at the bottle (which is under
pressure with no cap on the radiator to watch - it's on the bottle).

Have you drained the system lately? If so, it's possible to get an air
block in the hose between the reservoir and the thermostat housing.
That will over heat it in a hurry. This happens on refill it the hose
is higher than the bottom of the reservoir.

How about a/c? Mine started running warm in traffic this summer and it
turned out to be a diode in the module that connects to the coil of
the fan relay - it uses steering diodes to merge the radiator tank
sensor and the a/c switch for the electric fan. Fifty cent 1n4000
diode will cure that one - or get two and replqce both just to be
sure. Of course, the electric fan may only mask the problem as mine
ran all summer in West Texas a year or so back with the electric fan
unplugged...

Sounds like either a water pump or a sticking thermostat. Either one
will cause the problem you describe.

On Tue, 19 Sep 2006 02:36:01 UTC "DougW"
<post.replies@invalid.address> wrote:

> Clint wrote:
> > So we had a really hot day here awhile ago, and I ended up
> > overheating my Jeep Comanche (4.0l engine). I had problems before,
> > but nothing like that. Stuck in stop and go traffic, hot temps, etc.
> >
> > So I'm trying to do a little diagnosis, but I'm not that automotively
> > inclined. But what I'm seeing if very little coolant flow when the
> > Jeep is idling. I have no way of measuring it, but it seems to just
> > be trickling into the tank. When I had my helper/wife rev it up to
> > 2000 rpm, it flowed much faster, but still not a torrent or anything.
> >
> > Is it possible that the water pump has gone caput, even though it's
> > not locked up or anything? Should I start with just replacing that?
>
> Very possible the vanes have gone. It's also possible your radiator
> is clogged. Is there a lot of buildup in it?
>
> Keep in mind coolant flow when cold will be slow. That's the job
> of the thermostat valve. Full flow will only happen when the engine
> is at operating temperature. Needless to say the system is under
> pressure at that point and removing the radiator cap to look will
> get you seriously burned.
>


--
Will Honea

Re: 88 Jeep Comanche cooling issues
 

I'm watching the coolant flow as it comes into the bottle (taking off the
cap). I can see it speed up when someone tweaks the throttle to 1.5K, and
watch it slow down to a trickle when it gets to idle. That makes sense,
because as I was trying to struggle home after overheating, the temp would
stay down until I was standing still, and even then I could keep the temps
kind of down if I kept the rpm's up higher than idle.

These issues have started since I replaced the thermostat. I THINK the
thermostat is doing it's job, as it heats up, and then usually levels off
just under halfway on the temp gauge, which sounds right.

I don't have A/C, so I don't know if that affects your input. :)

Clint

"Will Honea" <whonea@yahoo.com> wrote in message
news:JxX2tWiP5BNp-pn2-vVTHkddUhv2i@anon.none.net...
> Where are you watching the coolant flow? My 88 MJ has that @#$% closed
> system so I don't really see the flow at the bottle (which is under
> pressure with no cap on the radiator to watch - it's on the bottle).
>
> Have you drained the system lately? If so, it's possible to get an air
> block in the hose between the reservoir and the thermostat housing.
> That will over heat it in a hurry. This happens on refill it the hose
> is higher than the bottom of the reservoir.
>
> How about a/c? Mine started running warm in traffic this summer and it
> turned out to be a diode in the module that connects to the coil of
> the fan relay - it uses steering diodes to merge the radiator tank
> sensor and the a/c switch for the electric fan. Fifty cent 1n4000
> diode will cure that one - or get two and replqce both just to be
> sure. Of course, the electric fan may only mask the problem as mine
> ran all summer in West Texas a year or so back with the electric fan
> unplugged...
>
> Sounds like either a water pump or a sticking thermostat. Either one
> will cause the problem you describe.
>
> On Tue, 19 Sep 2006 02:36:01 UTC "DougW"
> <post.replies@invalid.address> wrote:
>
>> Clint wrote:
>> > So we had a really hot day here awhile ago, and I ended up
>> > overheating my Jeep Comanche (4.0l engine). I had problems before,
>> > but nothing like that. Stuck in stop and go traffic, hot temps, etc.
>> >
>> > So I'm trying to do a little diagnosis, but I'm not that automotively
>> > inclined. But what I'm seeing if very little coolant flow when the
>> > Jeep is idling. I have no way of measuring it, but it seems to just
>> > be trickling into the tank. When I had my helper/wife rev it up to
>> > 2000 rpm, it flowed much faster, but still not a torrent or anything.
>> >
>> > Is it possible that the water pump has gone caput, even though it's
>> > not locked up or anything? Should I start with just replacing that?
>>
>> Very possible the vanes have gone. It's also possible your radiator
>> is clogged. Is there a lot of buildup in it?
>>
>> Keep in mind coolant flow when cold will be slow. That's the job
>> of the thermostat valve. Full flow will only happen when the engine
>> is at operating temperature. Needless to say the system is under
>> pressure at that point and removing the radiator cap to look will
>> get you seriously burned.
>>
>
>
> --
> Will Honea

Re: 88 Jeep Comanche cooling issues
 

I'm watching the coolant flow as it comes into the bottle (taking off the
cap). I can see it speed up when someone tweaks the throttle to 1.5K, and
watch it slow down to a trickle when it gets to idle. That makes sense,
because as I was trying to struggle home after overheating, the temp would
stay down until I was standing still, and even then I could keep the temps
kind of down if I kept the rpm's up higher than idle.

These issues have started since I replaced the thermostat. I THINK the
thermostat is doing it's job, as it heats up, and then usually levels off
just under halfway on the temp gauge, which sounds right.

I don't have A/C, so I don't know if that affects your input. :)

Clint

"Will Honea" <whonea@yahoo.com> wrote in message
news:JxX2tWiP5BNp-pn2-vVTHkddUhv2i@anon.none.net...
> Where are you watching the coolant flow? My 88 MJ has that @#$% closed
> system so I don't really see the flow at the bottle (which is under
> pressure with no cap on the radiator to watch - it's on the bottle).
>
> Have you drained the system lately? If so, it's possible to get an air
> block in the hose between the reservoir and the thermostat housing.
> That will over heat it in a hurry. This happens on refill it the hose
> is higher than the bottom of the reservoir.
>
> How about a/c? Mine started running warm in traffic this summer and it
> turned out to be a diode in the module that connects to the coil of
> the fan relay - it uses steering diodes to merge the radiator tank
> sensor and the a/c switch for the electric fan. Fifty cent 1n4000
> diode will cure that one - or get two and replqce both just to be
> sure. Of course, the electric fan may only mask the problem as mine
> ran all summer in West Texas a year or so back with the electric fan
> unplugged...
>
> Sounds like either a water pump or a sticking thermostat. Either one
> will cause the problem you describe.
>
> On Tue, 19 Sep 2006 02:36:01 UTC "DougW"
> <post.replies@invalid.address> wrote:
>
>> Clint wrote:
>> > So we had a really hot day here awhile ago, and I ended up
>> > overheating my Jeep Comanche (4.0l engine). I had problems before,
>> > but nothing like that. Stuck in stop and go traffic, hot temps, etc.
>> >
>> > So I'm trying to do a little diagnosis, but I'm not that automotively
>> > inclined. But what I'm seeing if very little coolant flow when the
>> > Jeep is idling. I have no way of measuring it, but it seems to just
>> > be trickling into the tank. When I had my helper/wife rev it up to
>> > 2000 rpm, it flowed much faster, but still not a torrent or anything.
>> >
>> > Is it possible that the water pump has gone caput, even though it's
>> > not locked up or anything? Should I start with just replacing that?
>>
>> Very possible the vanes have gone. It's also possible your radiator
>> is clogged. Is there a lot of buildup in it?
>>
>> Keep in mind coolant flow when cold will be slow. That's the job
>> of the thermostat valve. Full flow will only happen when the engine
>> is at operating temperature. Needless to say the system is under
>> pressure at that point and removing the radiator cap to look will
>> get you seriously burned.
>>
>
>
> --
> Will Honea

Re: 88 Jeep Comanche cooling issues
 

I'm watching the coolant flow as it comes into the bottle (taking off the
cap). I can see it speed up when someone tweaks the throttle to 1.5K, and
watch it slow down to a trickle when it gets to idle. That makes sense,
because as I was trying to struggle home after overheating, the temp would
stay down until I was standing still, and even then I could keep the temps
kind of down if I kept the rpm's up higher than idle.

These issues have started since I replaced the thermostat. I THINK the
thermostat is doing it's job, as it heats up, and then usually levels off
just under halfway on the temp gauge, which sounds right.

I don't have A/C, so I don't know if that affects your input. :)

Clint

"Will Honea" <whonea@yahoo.com> wrote in message
news:JxX2tWiP5BNp-pn2-vVTHkddUhv2i@anon.none.net...
> Where are you watching the coolant flow? My 88 MJ has that @#$% closed
> system so I don't really see the flow at the bottle (which is under
> pressure with no cap on the radiator to watch - it's on the bottle).
>
> Have you drained the system lately? If so, it's possible to get an air
> block in the hose between the reservoir and the thermostat housing.
> That will over heat it in a hurry. This happens on refill it the hose
> is higher than the bottom of the reservoir.
>
> How about a/c? Mine started running warm in traffic this summer and it
> turned out to be a diode in the module that connects to the coil of
> the fan relay - it uses steering diodes to merge the radiator tank
> sensor and the a/c switch for the electric fan. Fifty cent 1n4000
> diode will cure that one - or get two and replqce both just to be
> sure. Of course, the electric fan may only mask the problem as mine
> ran all summer in West Texas a year or so back with the electric fan
> unplugged...
>
> Sounds like either a water pump or a sticking thermostat. Either one
> will cause the problem you describe.
>
> On Tue, 19 Sep 2006 02:36:01 UTC "DougW"
> <post.replies@invalid.address> wrote:
>
>> Clint wrote:
>> > So we had a really hot day here awhile ago, and I ended up
>> > overheating my Jeep Comanche (4.0l engine). I had problems before,
>> > but nothing like that. Stuck in stop and go traffic, hot temps, etc.
>> >
>> > So I'm trying to do a little diagnosis, but I'm not that automotively
>> > inclined. But what I'm seeing if very little coolant flow when the
>> > Jeep is idling. I have no way of measuring it, but it seems to just
>> > be trickling into the tank. When I had my helper/wife rev it up to
>> > 2000 rpm, it flowed much faster, but still not a torrent or anything.
>> >
>> > Is it possible that the water pump has gone caput, even though it's
>> > not locked up or anything? Should I start with just replacing that?
>>
>> Very possible the vanes have gone. It's also possible your radiator
>> is clogged. Is there a lot of buildup in it?
>>
>> Keep in mind coolant flow when cold will be slow. That's the job
>> of the thermostat valve. Full flow will only happen when the engine
>> is at operating temperature. Needless to say the system is under
>> pressure at that point and removing the radiator cap to look will
>> get you seriously burned.
>>
>
>
> --
> Will Honea