Coolant Circulation Problem

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Oct 27, 2005 | 12:38 PM

THOBBS

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Coolant Circulation Problem

1997 Ford F150 4.6L V8 Automatic 4WD
(1) Heater Not Blowing out warm air
(2) Temperature quage may all at once go to hot position, turn ignition
off then wait 1 to 2 minutes turn back on temperature guage back to
normal, engine not running hot
(3) Upper radiator hose hard as a rock, loosen degas bottle cap, pressure
disappears, tighten degas bottle cap and drive down road pressure on hose
reappears
(3) Changed Degas Bottle Cap
(4) Changed Thermostat
(5) Took upper radiator hose off at radiator, engine warms up, thermostat
opens and coolant starts coming out of hose
(6) What can it be, Please help if possible
(7) Thanks,

Oct 27, 2005 | 12:51 PM

BrianA

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From: Trussville, Alabama

Have all symptoms persisted after steps (4) and (5) ?

I'd say number (2) is normal. Once at operating temp the system is pressurized. Release the pressure and the hoses will get softer.

It sounds much like a faulty thermostat, that's why I asked the first question.

If the heater is not blowing hot air, then
a) the heater core is clogged
or
b) hot water is not available (faulty thermostat).

Where is your temp indicator sitting when the heater does nto blow hot air.
Did all this start just recently, when the weather turned cold?

Oct 27, 2005 | 01:04 PM

THOBBS

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Reply to BrianA

(1) Have all symptoms persisted after steps (4) and (5) Yes

(2) Temp indicator sitting in same location it always has in the normal range

(3) The last time I used the heater was probably 6 months ago other than using the defroster at times

Oct 28, 2005 | 11:17 AM

lancekilgore

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there is aplenum door that I am told is what controls the heat, in this vehicle, if you open turn on the heat it is suppose to devert the air through the heater core. BUt if it is older and has the valve on the outside in the engine area look at the heater hoses going in and out and see if there is a valve there and it operates (opens and closes when the **** is turned. You can easily check the heater core for bockage by removing the return heater hose in the heater core in the engine compart ment and if there is coolant coming through it is not clogged, (could be very messy be prepared).

Lance

Dec 19, 2005 | 10:36 PM

akfordowner

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Has anyone found a definitive answer to this problem? My 97' F-150 has the same problem.

Dec 21, 2005 | 11:04 AM

THOBBS

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Thobbs

I guess you could say that it solved the problem itself as on Thanksgiving day it blew a head gasket

Dec 21, 2005 | 05:27 PM

steve(ill)

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many temp problems, that you can detect with the gauge moving erratic, are related to low coolant level. i would guess the head gasket was leaking using coolant, which caused the low water level and poor heater performance. eventually the head gasket let go.