radiator fans on all the time

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gazjoiner

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12
Location
barnsley
hi

ive recently bought a freelander td4 its a 2002 reg .for the last week i noticed the fans coming on after a about 10 mins of driving and staying on the temp gauge never moved above the middle . i checked the coolant expansion tank and it was up to the max line but could hear a slight hissing from the cap. while driving today all the coolant came out pass the cap on the expansion tank but the temp gauge never showed it was over heating and the fans on the rad were on full pelt . i let it cool down and topped expansion tank backup , after 10 mins the water came pass the cap again ( really hot both times ) and again the temp gauge never moved above normal operating temp. the top hose on the rad was red hot the bottom hose cold. when i squeezed the bottom hose i could hear water moving about . is it a case of faulty cap causing this or something more serious ?

thanks in advance
 
gazjoiner said:
hi

ive recently bought a freelander td4 its a 2002 reg .for the last week i noticed the fans coming on after a about 10 mins of driving and staying on the temp gauge never moved above the middle . i checked the coolant expansion tank and it was up to the max line but could hear a slight hissing from the cap. while driving today all the coolant came out pass the cap on the expansion tank but the temp gauge never showed it was over heating and the fans on the rad were on full pelt . i let it cool down and topped expansion tank backup , after 10 mins the water came pass the cap again ( really hot both times ) and again the temp gauge never moved above normal operating temp. the top hose on the rad was red hot the bottom hose cold. when i squeezed the bottom hose i could hear water moving about . is it a case of faulty cap causing this or something more serious ?

thanks in advance
Click to expand...
Sounds like your cap is warn out and allowing the pressure to disperse. The expansion tank is only there because of having no radiator cap in general. Problems can arise from thermo not opening, blockage from crud or water pump failure and expansion tank not sealing correctly/ not forgetting overfilling.
Did any of the main hoses feel soft easier to squeeze?
 
saxavordian said:
Sounds like your cap is warn out and allowing the pressure to disperse. The expansion tank is only there because of having no radiator cap in general. Problems can arise from thermo not opening, blockage from crud or water pump failure and expansion tank not sealing correctly/ not forgetting overfilling.
Did any of the main hoses feel soft easier to squeeze?
Click to expand...
The top hose felt easier to squeeze but I'm thinking that's because it was red hot and softened the hose. The cap can be pushed nearly all the way on without twisting it on then it tightens so far and it will click and slacken off . The cap on mine is a orange one. The heater blows out hot ( when put on warm ) untill the water came out of the expansion tank then it blew cold
 
Last edited:
gazjoiner said:
The top hose felt easier to squeeze but I'm thinking that's because it was red hot and softened the hose. The cap can be pushed nearly all the way on without twisting it on then it tightens so far and it will click and slacken off . The cap on mine is a orange one. The heater blows out hot ( when put on warm ) untill the water came out of the expansion tank then it blew cold
Click to expand...


this morning i filled the expansion tank up to max started car and left the cap off as it got up to temp the coolant went down to minimum and started to return to the tank via the top house ( does this mean thermostat isnt stuck closed ).. i left it running once at operating temp for 15 mins the fans didnt come on and the coolant didnt gush out of the tank is this pointing to the cap been faulty ?
 
Possible. The thermo opens and releases the hot water via the top hose which drains into the radiator. This where the fans kick in to cool the water through the vanes enough to go back via the bottom hose the to the water pump into the engine. If the cap isn't sealed normal pressure in the radiator finds an outlet hence the expansion tank. IF YOU HAD BLOCKAGE in the radiator the bottom hose would be soft and the water pump would overheat leading to the engine seizure.
Likewise if the engine block also being blocked this would cause back pressure on the water pump break and damage from hence with no flow onwards. The brunt of the flow first would head out the expansion tank or core plugs. Replace the the cap first if not happy then the thermostat second.
 
saxavordian said:
Possible. The thermo opens and releases the hot water via the top hose which drains into the radiator. This where the fans kick in to cool the water through the vanes enough to go back via the bottom hose the to the water pump into the engine. If the cap isn't sealed normal pressure in the radiator finds an outlet hence the expansion tank. IF YOU HAD BLOCKAGE in the radiator the bottom hose would be soft and the water pump would overheat leading to the engine seizure.
Likewise if the engine block also being blocked this would cause back pressure on the water pump break and damage from hence with no flow onwards. The brunt of the flow first would head out the expansion tank or core plugs. Replace the the cap first if not happy then the thermostat second.
Click to expand...
I have fitted a new cap today and noticed under the warning sticker thing on top of the expansion tank small cracks so that be next thing to change as when engine was running the coolant that the top hose brings back into the tank was coming out through these cracks
 
If the air con is switched on, or if the air distribution is switched to screen (to bring the air con on,air con switch on or off), the fans will run.
 
I had the same problem with my petrol freelander. The expansion tankhad hair line cracks around he neck so changed the tank for a new one. I just took he top water feed off ythe old tank and ran the engine to empty the old tank in order to get the bottom hose off the tank. I then fitted the new tank and re filled with red coolant. I then ran the engine and opened the two bleed screws. The petrol engine has two and once bubble free coolant came out the first bleed hole I closed that then when it came out of he second bleed screw I closed thst off. Make sure that the heater control is turned to hot inside the car. Run it and keep checking the coolant level.
 
If you are trying to empty your expansion tank you could drain with a external suction pump syphoner into a container until dry enough then carefully remove the hose. As long as the hose is upright the coolant loss will be minimal for to reattach a new expansion tank. Pending on the condition of the syphoned liquid you could retop the new tank.
 
saxavordian said:
If you are trying to empty your expansion tank you could drain with a external suction pump syphoner into a container until dry enough then carefully remove the hose. As long as the hose is upright the coolant loss will be minimal for to reattach a new expansion tank. Pending on the condition of the syphoned liquid you could retop the new tank.
Click to expand...
Quick update . Changed expansion tank and cap still doing the same . Had the thermostat changed and all is well 2 hr drive stuck in traffic etc and no problems . Fingers crossed it stays that way.
Thanks for all the advice
 
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