Temp indicator still going up and down
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Junior User
Joined: Nov 2003
Posts: 85
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From: Switzerland
Temp indicator still going up and down
I’m still working on the heating problem on my 1988 Bronco II 2.9L
When driving the temperature indicator goes up about 4 mm under the red hot line and then drops again slowly at the normal level.
I changed now the Thermostat, temp gauge and radiator pressure cap but nothing changed.
I do not lose any coolant and there is no coolant in the oil that good indicate a cracked head casket. In the coolant I don’t smell exhaust gases so it is not clear to me what is causing this.
Can this have something to do with the water pump or Fan clutch, and how can I test these.
I noticed that when the engine is a working temperature the fan can be easy turned by hand with a minimum force.
Ray
When driving the temperature indicator goes up about 4 mm under the red hot line and then drops again slowly at the normal level.
I changed now the Thermostat, temp gauge and radiator pressure cap but nothing changed.
I do not lose any coolant and there is no coolant in the oil that good indicate a cracked head casket. In the coolant I don’t smell exhaust gases so it is not clear to me what is causing this.
Can this have something to do with the water pump or Fan clutch, and how can I test these.
I noticed that when the engine is a working temperature the fan can be easy turned by hand with a minimum force.
Ray
Postmaster
Joined: Dec 2001
Posts: 3,742
Likes: 2
From: UT
The only time that turning the fan by hand successfully "tested" the fan clutch was when the fan clutch was "seized". The best way I've found to test the fan clutch is described in a Mitchell manual. You remove the fan clutch, release the thermostatic spring from the outer notch it sits in, rotate it 1/4 turn CCW, reinstall, and see if anything improves. Releasing that spring eliminates the fans response to temperature changes so it will spin it's fastest all the time.
Another possibility is a fault in the temperature sender. You might consider checking the engine temperature with another gauge (I would use the ECT sensor for the computer) to see if the temperature is truly fluctuating as indicated.
Another possibility is a fault in the temperature sender. You might consider checking the engine temperature with another gauge (I would use the ECT sensor for the computer) to see if the temperature is truly fluctuating as indicated.
Thread Starter
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Junior User
Joined: Nov 2003
Posts: 85
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From: Switzerland
When the engine is cold for me it seems that there is not really more force needed then when it is hot.
On idling the temp is normal, so this shut mean that the fan cools ok, also when I drive and the temp is rising up it goes back to normal levels after a while. It seems to me a loop; the temp is going up and down. The new temp sender installed did not solve this, the readings are the same as the old one.
On idling the temp is normal, so this shut mean that the fan cools ok, also when I drive and the temp is rising up it goes back to normal levels after a while. It seems to me a loop; the temp is going up and down. The new temp sender installed did not solve this, the readings are the same as the old one.
Thread Starter
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Junior User
Joined: Nov 2003
Posts: 85
Likes: 0
From: Switzerland
Bronco II 2.9L 4x4 XLT 1988 95000 miles
Hi,
I own the car for 2 months now.
When I bought it the temp was always low on the gauge it hardly came up, then I asked my dealer to put in a new thermostat and the problem started, I thought the thermostat was erratic so again they put in a new one but the problem staid.
(I studied the Haynes manual and there shut be an air hole in the thermostat only in one position, maybe they mounted it the wrong way)
I actually don’t no when the system was flushed & the antifreeze changed
Also I changed the temp sender without success.
I don’t lose any coolant and also it do not smell exhaust gases in the coolant.
Ray
Hi,
I own the car for 2 months now.
When I bought it the temp was always low on the gauge it hardly came up, then I asked my dealer to put in a new thermostat and the problem started, I thought the thermostat was erratic so again they put in a new one but the problem staid.
(I studied the Haynes manual and there shut be an air hole in the thermostat only in one position, maybe they mounted it the wrong way)
I actually don’t no when the system was flushed & the antifreeze changed
Also I changed the temp sender without success.
I don’t lose any coolant and also it do not smell exhaust gases in the coolant.
Ray
Elder User
Joined: Aug 2000
Posts: 763
Likes: 0
From: home
cooling
A loose warn water pump could possibily be the problem. Usually they start leaking if the seal is shot. I have seen it where the blades for the pump are broken off the shaft & the car over heats. Also seen it where the blades are eaten down from corrrison & cause the vehicle to run hotter. I would back flush the cooling system before I changed out the water pump. Than if that does not do it , than change the water pump. You do not want to put on a new pump with crud in the system. 
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Thread Starter
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Junior User
Joined: Nov 2003
Posts: 85
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From: Switzerland
Well invested a lot of money today without any success.
Changed the radiator, flushed the system, put in new antifreeze coolant, and cleaned the condenser in front of the radiator and nothing changed.
The only thing improved is that the temp indicator returns quicker to normal level at idle.
Also checked the timing of the engine and pressure tested the coolant system
Ray
Changed the radiator, flushed the system, put in new antifreeze coolant, and cleaned the condenser in front of the radiator and nothing changed.
The only thing improved is that the temp indicator returns quicker to normal level at idle.
Also checked the timing of the engine and pressure tested the coolant system
Ray
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