Mike Romain

On an 88, the first suspect when overheating is a bad rad fan clutch.
When this goes bad it overheats when revving slow.

To test this, heat up the engine fully and have someone shut it down
while you watch the fan. A good clutch will stop the fan almost
instantly when hot. If it keeps on spinning, you need a new fan clutch.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

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

Mike Romain

On an 88, the first suspect when overheating is a bad rad fan clutch.
When this goes bad it overheats when revving slow.

To test this, heat up the engine fully and have someone shut it down
while you watch the fan. A good clutch will stop the fan almost
instantly when hot. If it keeps on spinning, you need a new fan clutch.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

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

Mike Romain

On an 88, the first suspect when overheating is a bad rad fan clutch.
When this goes bad it overheats when revving slow.

To test this, heat up the engine fully and have someone shut it down
while you watch the fan. A good clutch will stop the fan almost
instantly when hot. If it keeps on spinning, you need a new fan clutch.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

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

Will Honea

No a/c, no electric fan <G>. Without the a/c, it wouldn't kick in
until it got very near the redline anyway.

That flow bothers me - it says that you are cycling copious quantities
thru the bottle - and mine does almost nothing except on shutdown and
shortly after starting. Acts almost the same as an ordinary overflow
bottle in an open system. The only time I see that kind of flow is
when I have just re-filled the system and it is purging the rest of
the air out as it heats up and pulling the fluid out the bottom to
replace the air. Normally, on shutdown it will fill a little then get
drawn down as the engine runs on rerstart. I'd guess that something
is plugged - radiator, collapsed intake hose, etc.

Mike's suggestion on the fan clutch is a good possibility as well -
and easy to test.

On Tue, 19 Sep 2006 04:41:28 UTC "Clint" <nobody@nowhere.none> wrote:

> 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
>
>


--
Will Honea

Will Honea

No a/c, no electric fan <G>. Without the a/c, it wouldn't kick in
until it got very near the redline anyway.

That flow bothers me - it says that you are cycling copious quantities
thru the bottle - and mine does almost nothing except on shutdown and
shortly after starting. Acts almost the same as an ordinary overflow
bottle in an open system. The only time I see that kind of flow is
when I have just re-filled the system and it is purging the rest of
the air out as it heats up and pulling the fluid out the bottom to
replace the air. Normally, on shutdown it will fill a little then get
drawn down as the engine runs on rerstart. I'd guess that something
is plugged - radiator, collapsed intake hose, etc.

Mike's suggestion on the fan clutch is a good possibility as well -
and easy to test.

On Tue, 19 Sep 2006 04:41:28 UTC "Clint" <nobody@nowhere.none> wrote:

> 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
>
>


--
Will Honea

Will Honea

No a/c, no electric fan <G>. Without the a/c, it wouldn't kick in
until it got very near the redline anyway.

That flow bothers me - it says that you are cycling copious quantities
thru the bottle - and mine does almost nothing except on shutdown and
shortly after starting. Acts almost the same as an ordinary overflow
bottle in an open system. The only time I see that kind of flow is
when I have just re-filled the system and it is purging the rest of
the air out as it heats up and pulling the fluid out the bottom to
replace the air. Normally, on shutdown it will fill a little then get
drawn down as the engine runs on rerstart. I'd guess that something
is plugged - radiator, collapsed intake hose, etc.

Mike's suggestion on the fan clutch is a good possibility as well -
and easy to test.

On Tue, 19 Sep 2006 04:41:28 UTC "Clint" <nobody@nowhere.none> wrote:

> 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
>
>


--
Will Honea

Clint

Huh. I figured it should be circulating on a regular basis.

Thanks for your input, both you and Mike. I took it into the shop for an
estimate; it's a small town, and they've been gentle with me in the past. :)
I'll post back in here when I find out what it is. The guy who owns the
shop did 20 years at a Jeep dealer in the nearby big city, and he indicated
a common failure was the radiator itself.

In the meantime, I'll just lube up my wallet...

Clint

"Will Honea" <whonea@yahoo.com> wrote in message
news:JxX2tWiP5BNp-pn2-9sKEF9vXE4kX@anon.none.net...
> No a/c, no electric fan <G>. Without the a/c, it wouldn't kick in
> until it got very near the redline anyway.
>
> That flow bothers me - it says that you are cycling copious quantities
> thru the bottle - and mine does almost nothing except on shutdown and
> shortly after starting. Acts almost the same as an ordinary overflow
> bottle in an open system. The only time I see that kind of flow is
> when I have just re-filled the system and it is purging the rest of
> the air out as it heats up and pulling the fluid out the bottom to
> replace the air. Normally, on shutdown it will fill a little then get
> drawn down as the engine runs on rerstart. I'd guess that something
> is plugged - radiator, collapsed intake hose, etc.
>
> Mike's suggestion on the fan clutch is a good possibility as well -
> and easy to test.
>
> On Tue, 19 Sep 2006 04:41:28 UTC "Clint" <nobody@nowhere.none> wrote:
>
>> 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
>>
>>
>
>
> --
> Will Honea
>

Clint

Huh. I figured it should be circulating on a regular basis.

Thanks for your input, both you and Mike. I took it into the shop for an
estimate; it's a small town, and they've been gentle with me in the past. :)
I'll post back in here when I find out what it is. The guy who owns the
shop did 20 years at a Jeep dealer in the nearby big city, and he indicated
a common failure was the radiator itself.

In the meantime, I'll just lube up my wallet...

Clint

"Will Honea" <whonea@yahoo.com> wrote in message
news:JxX2tWiP5BNp-pn2-9sKEF9vXE4kX@anon.none.net...
> No a/c, no electric fan <G>. Without the a/c, it wouldn't kick in
> until it got very near the redline anyway.
>
> That flow bothers me - it says that you are cycling copious quantities
> thru the bottle - and mine does almost nothing except on shutdown and
> shortly after starting. Acts almost the same as an ordinary overflow
> bottle in an open system. The only time I see that kind of flow is
> when I have just re-filled the system and it is purging the rest of
> the air out as it heats up and pulling the fluid out the bottom to
> replace the air. Normally, on shutdown it will fill a little then get
> drawn down as the engine runs on rerstart. I'd guess that something
> is plugged - radiator, collapsed intake hose, etc.
>
> Mike's suggestion on the fan clutch is a good possibility as well -
> and easy to test.
>
> On Tue, 19 Sep 2006 04:41:28 UTC "Clint" <nobody@nowhere.none> wrote:
>
>> 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
>>
>>
>
>
> --
> Will Honea
>

Clint

Huh. I figured it should be circulating on a regular basis.

Thanks for your input, both you and Mike. I took it into the shop for an
estimate; it's a small town, and they've been gentle with me in the past. :)
I'll post back in here when I find out what it is. The guy who owns the
shop did 20 years at a Jeep dealer in the nearby big city, and he indicated
a common failure was the radiator itself.

In the meantime, I'll just lube up my wallet...

Clint

"Will Honea" <whonea@yahoo.com> wrote in message
news:JxX2tWiP5BNp-pn2-9sKEF9vXE4kX@anon.none.net...
> No a/c, no electric fan <G>. Without the a/c, it wouldn't kick in
> until it got very near the redline anyway.
>
> That flow bothers me - it says that you are cycling copious quantities
> thru the bottle - and mine does almost nothing except on shutdown and
> shortly after starting. Acts almost the same as an ordinary overflow
> bottle in an open system. The only time I see that kind of flow is
> when I have just re-filled the system and it is purging the rest of
> the air out as it heats up and pulling the fluid out the bottom to
> replace the air. Normally, on shutdown it will fill a little then get
> drawn down as the engine runs on rerstart. I'd guess that something
> is plugged - radiator, collapsed intake hose, etc.
>
> Mike's suggestion on the fan clutch is a good possibility as well -
> and easy to test.
>
> On Tue, 19 Sep 2006 04:41:28 UTC "Clint" <nobody@nowhere.none> wrote:
>
>> 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
>>
>>
>
>
> --
> Will Honea
>

billy ray

If the fluid is flowing unhindered in and out of the bottle (if you can
watch circulation) makes it sounds that the radiator cap is bad.

A lot of places now recommend new thermostats and caps at each coolant
change (especially when DexCool is used) because the failure rate is
increasing tremendously.


"Clint" <nobody@nowhere.none> wrote in message
news:Rv7Qg.572414$IK3.231321@pd7tw1no...
> Huh. I figured it should be circulating on a regular basis.
>
> Thanks for your input, both you and Mike. I took it into the shop for an
> estimate; it's a small town, and they've been gentle with me in the past.
> :) I'll post back in here when I find out what it is. The guy who owns
> the shop did 20 years at a Jeep dealer in the nearby big city, and he
> indicated a common failure was the radiator itself.
>
> In the meantime, I'll just lube up my wallet...
>
> Clint
>
> "Will Honea" <whonea@yahoo.com> wrote in message
> news:JxX2tWiP5BNp-pn2-9sKEF9vXE4kX@anon.none.net...
>> No a/c, no electric fan <G>. Without the a/c, it wouldn't kick in
>> until it got very near the redline anyway.
>>
>> That flow bothers me - it says that you are cycling copious quantities
>> thru the bottle - and mine does almost nothing except on shutdown and
>> shortly after starting. Acts almost the same as an ordinary overflow
>> bottle in an open system. The only time I see that kind of flow is
>> when I have just re-filled the system and it is purging the rest of
>> the air out as it heats up and pulling the fluid out the bottom to
>> replace the air. Normally, on shutdown it will fill a little then get
>> drawn down as the engine runs on rerstart. I'd guess that something
>> is plugged - radiator, collapsed intake hose, etc.
>>
>> Mike's suggestion on the fan clutch is a good possibility as well -
>> and easy to test.
>>
>> On Tue, 19 Sep 2006 04:41:28 UTC "Clint" <nobody@nowhere.none> wrote:
>>
>>> 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
>>>
>>>
>>
>>
>> --
>> Will Honea
>>
>
>