Loss of coolant

My 1998 Mountaineer 5.0, AWD with 120,000 miles is loosing coolant. I
can leave the car in the driveway for 4-5 hours and no leak. However,
each morning I can see small puddles on the garage floor. I am unable
to locate the leak visually. Also, I have used a pressure tester and
it holds 15 PSI for more than 10 minutes. The vehicle does not smoke
on start-up, except for chilly mornings.
In case climate is a concern, I live in northern Arkansas.
Thanks for any and all help.
Steve

On Wed, 2 Dec 2009 10:08:52 -0800 (PST), Steve
> wrote:

>My 1998 Mountaineer 5.0, AWD with 120,000 miles is loosing coolant. I
>can leave the car in the driveway for 4-5 hours and no leak. However,
>each morning I can see small puddles on the garage floor. I am unable
>to locate the leak visually. Also, I have used a pressure tester and
>it holds 15 PSI for more than 10 minutes.

Only 10 minutes? That's not good. Should hold pressure overnight when
using a pressure tester, or at least a few hours. Not minutes.

Suggestion... First wash everything off good. Next using that pressure
tester, pump it up, and each time it drops off pump up again. You may
have to do it a few times (five or six) then look for coolant, both on
the floor and on the engine. Use good lighting, too. Very important.

>The vehicle does not smoke
>on start-up, except for chilly mornings.
>In case climate is a concern, I live in northern Arkansas.
>Thanks for any and all help.
>Steve

On Wed, 2 Dec 2009 10:08:52 -0800 (PST), Steve
> wrote:

>My 1998 Mountaineer 5.0, AWD with 120,000 miles is loosing coolant. I
>can leave the car in the driveway for 4-5 hours and no leak. However,
>each morning I can see small puddles on the garage floor. I am unable
>to locate the leak visually. Also, I have used a pressure tester and
>it holds 15 PSI for more than 10 minutes. The vehicle does not smoke
>on start-up, except for chilly mornings.
>In case climate is a concern, I live in northern Arkansas.
>Thanks for any and all help.
>Steve

Sometimes the crimped on side tanks on the radiator leak when cold but
stop leaking when heated up. I have had some success crimping them
tighter with vise grips.

Steve > wrote in news:d8e7ebf4-47e8-4178-a3ff-
:

> My 1998 Mountaineer 5.0, AWD with 120,000 miles is loosing coolant. I
> can leave the car in the driveway for 4-5 hours and no leak. However,
> each morning I can see small puddles on the garage floor. I am unable
> to locate the leak visually. Also, I have used a pressure tester and
> it holds 15 PSI for more than 10 minutes. The vehicle does not smoke
> on start-up, except for chilly mornings.
> In case climate is a concern, I live in northern Arkansas.
> Thanks for any and all help.
> Steve

Check the heater control valve. It's leaking on my 2002, and I think your
year may use the same valve. If you don't know what to look for, it's
inline with the heater hose going to the the fire wall and has a vacuum
controlled valve. Mine only leaked above idle. I found the leak by
smelling it and noting dried coolant on the valve. Had someone rev the
engine while I watched and coolant leaked out. Replaced it and all's
well.

On Fri, 4 Dec 2009 08:46:43 +0000 (UTC), wrote:

>Steve > wrote in news:d8e7ebf4-47e8-4178-a3ff-
:
>
>> My 1998 Mountaineer 5.0, AWD with 120,000 miles is loosing coolant. I
>> can leave the car in the driveway for 4-5 hours and no leak. However,
>> each morning I can see small puddles on the garage floor. I am unable
>> to locate the leak visually. Also, I have used a pressure tester and
>> it holds 15 PSI for more than 10 minutes. The vehicle does not smoke
>> on start-up, except for chilly mornings.
>> In case climate is a concern, I live in northern Arkansas.
>> Thanks for any and all help.
>> Steve
>
>Check the heater control valve. It's leaking on my 2002, and I think your
>year may use the same valve. If you don't know what to look for, it's
>inline with the heater hose going to the the fire wall and has a vacuum
>controlled valve. Mine only leaked above idle. I found the leak by
>smelling it and noting dried coolant on the valve. Had someone rev the
>engine while I watched and coolant leaked out. Replaced it and all's
>well.

My heater valve leaks only when the heat is set high. It's been that
way for a long time but does not leak enough to worry about.

On Dec 4, 8:16*am, Shoe > wrote:
> On Fri, 4 Dec 2009 08:46:43 +0000 (UTC), wrote:
> >Steve > wrote in news:d8e7ebf4-47e8-4178-a3ff-
> :
>
> >> My 1998 Mountaineer 5.0, AWD with 120,000 miles is loosing coolant. *I
> >> can leave the car in the driveway for 4-5 hours and no leak. *However,
> >> each morning I can see small puddles on the garage floor. *I am unable
> >> to locate the leak visually. *Also, I have used a pressure tester and
> >> it holds 15 PSI for more than 10 minutes. *The vehicle does not smoke
> >> on start-up, except for chilly mornings.
> >> In case climate is a concern, I live in northern Arkansas.
> >> Thanks for any and all help.
> >> Steve
>
> >Check the heater control valve. It's leaking on my 2002, and I think your
> >year may use the same valve. If you don't know what to look for, it's
> >inline with the heater hose going to the the fire wall and has a vacuum
> >controlled valve. Mine only leaked above idle. I found the leak by
> >smelling it and noting dried coolant on the valve. Had someone rev the
> >engine while I watched and coolant leaked out. Replaced it and all's
> >well.
>
> My heater valve leaks only when the heat is set high. *It's been that
> way for a long time but does not leak enough to worry about.- Hide quoted text -
>
> - Show quoted text -

Thanks to all who responded. It looks like I have my work cut out for
me.
I'll try to keep everyone updated on my progress.
Steve