Overheating probelm

[sti555]

hey guys iv searched the forum but cant find a decent answer on this issue.the cars a wrx the issue is that the radiator fans dont come on at all when the cars warm,even when i put the aircon on warm and high(blows hot air when i put my foot down) and the bottom radiator hose doesnt seem to warm up at all.the factory water temp gauge stays just about half way.but my aftermarket one reads 115 degrees celcius sometimes and sits at 105 degrees celcius when cruising or there abouts.the aftermarket gauge sender is coming from under the manifold behind the alternator..dont think its the sender though..im guessing its the thermostat,thermoswitch or waterpump.i am losing no coolant either

[94 Leone]

have you had a look at the thermostat? take it out drop it in a cup of boiling water: if it doesn\'t open: she\'s poked.

[sti555]

would that also cause the fans not to come on with the aircon on high?..other symptoms iv had is both the -10 hoses coming off the waterpump have split in the last month and the water coming out off them is hot,could that eliminate the waterpump failure. will be getting a cambelt kit fiited this week so if it is the thermostat will leave it till then as i replaced my coolant 2 days ago.and it aint cheap haha

[boon]

 sti555 said:

would that also cause the fans not to come on with the aircon on high?..other symptoms iv had is both the -10 hoses coming off the waterpump have split in the last month and the water coming out off them is hot,could that eliminate the waterpump failure. will be getting a cambelt kit fiited this week so if it is the thermostat will leave it till then as i replaced my coolant 2 days ago.and it aint cheap haha

Factory temperature sensor is probably on the cold side of the radiator. If it\'s not seeing hot, it won\'t turn the fans on. If your bottom rad hose isn\'t getting hot then the thermostat almost certainly isn\'t opening. Almost no water flowing = whole system is going to behave weirdly.

[Stoffa]

Check the fan relays in the engine bay as well

[Subirex Automotive]

check your fans first. disconnect the fan plug and put positive and earth and see if it comes on.

if the bottom hose is not getting warm than it probably could be the thermostat or partially blocked radiator.

[Stodart]

Over heating problems in subarus engines are universal its a case of systematically going thru everything as previously suggested like

1 themostat (this is easy to access / cheap to replace )

2 water pumps rarely fail (ie the impellor / housing) , what happens with them is that the bearings dry out - fail causing shaft play wearing out the seal causing them to leak compromising the cambelt (as pump driven here) which is part of this assembly.

3 check sender units / cooling fans as previously suggested, it could be just a blown fuse.

4 what you say about water temp dropping from 115 to 105 at cruising speeds suggests a blocked radiator so if problem not resolved by thermostat / fans / sender units get radiator flow tested by a radiator specialist

5 need to be carefull driving it in this state as if overheat engine you risk blowing head gaskets / cracking cylinderheads

[sti555]

cheers for the info.i just plugged in the 2 green diagnostics plugs under dash and the fan comes on so dont think its the sender or fuse

[Koom]

Has the cooling system been bled fully? Could be an air lock possibly?

[sti555]

i bleed it myself and cant see any bubbles in header tank.would this cause the fans to not come on though?

[94 Leone]

if the thermostat is poked: it wont be opening; thus it wont be letting hot water through, to the temperature sensors: therefore the fans will not turn on. check your thermostat.

[titian]

sensor for fans on engine side controlled by computer.Check voltage output to fans when hot. either no power or fans U/S. Fan on left runs with AC only if AC is operational.

diagnostic connectors will not tell you. ???

if you are not loosing fluid its just electrical.Thermostat will be ok.

This may help you ;)

[sti555]

update: so i just checked the bottom radiator hose again and it seems to be getting hot,and it uses no coolant what so ever..also there are no bubbles in the header tank so i pretty sure i bled it properly.checked the fuses/relay and they are good..if the thermostat was gone would the bottom hose still get hot.cheers

[titian]

Its electrical :o :o :o :

[94 Leone]

check all the fuses again: to be sure, and then check the wiring: to make sure it hasn\'t been damaged.

[sti555]

checked all fuses and wiring and all is good.anychance it could be the water temp sensor.iv heard that controls the fan relay and switch..i did a google search and a guy had a similar problem.ended up being the ecu ???

[titian]

Are you getting voltage at the fan plugs? Yes fans controlled by ECU.

Two temp sensors Are in the top water rail across the top of the engine.

Usually you will get a code if its the sensor,also other engine smooth running issues.

A signal is sent from ECU to the fan control relays in the box beside the washer water bottle. There is one relay for each fan. Check relay operation and signal too each with a multimeter.

Does sound like ECU fault though.

[Marky]

Dumb question time

How long are you leaving it to idle for the fans to not turn on

Does it start to cook itself eventually? I know mine takes forever for the fans to actually turn on

Just reading through it doesn\'t sound like there\'s an actual overheating problem - you just aren\'t catching the fans turn on?

Sorry if I\'m way off

[Guest]

Mine takes 3-5min to get to 91ish for the fan to come on. If you go for a thrash then idle in the driveway they normally cycle pretty quick.

[sti555]

yep there is voltage to both fans and iv checked relay and that seems good.and im not getting CEL for water temp sensors.oh no hopefully its not the ecu.the car reaches 105 degree celcius after 10mins driving and fans wont come on even after a hour drive.cheers

[titian]

 sti555 said:

yep there is voltage to both fans and iv checked relay and that seems good.and im not getting CEL for water temp sensors.oh no hopefully its not the ecu.the car reaches 105 degree celcius after 10mins driving and fans wont come on even after a hour drive.cheers

OK if no fans running and there is power at the plugs then its fans that require replacement ;)

Assuming there is a good electrical connection at the 3 pin plugs on each fan. ;D

[aim]

He said the fans powered on after a diagnostic check. I would seriously just check the thermostat, it\'s so easy and cheap to do. Could be stuck partially open. After that doesn\'t work, take it to someone who knows what they are doing in the electrical department.

[titian]

Oh True : Missed that one.

Sounds like cooling is so good fans do not need to come on. If infact both work with diagnostic plugs connected.

One fan could be faulty. As no fan with aircon on

Why do you think it is overheating? Could be faulty indication on dash?

105C good temp for INLET to radiator (Upper Hose)

[sti555]

so i just checked the thermostat and to my suprise it is opening when placed in boiling water..when removing the bottom radiator hose to check thermostat there was hot water coming out of the hose for a couple seconds max 500ml then the rest was cold which was about 2 litres this came out of bottom radiator hose.then about 2-3 Litres of hot water was slowly dripping from thermostat housing/engine side.the bottom hose gets no where near as hot as the top ..is this a bad waterpump.is there a way to check if the waterpumps gone ie run car with hose go through top tank..still the car uses no coolant or leaks any...one thing i did notice is that the thermostat housing had lil corrosion pieces on inside and they scratch off..so now im thinking its either a blocked radiator,waterpump,ecu,..the fans dont come on when i use the a/c either..im really stumped

[sti555]

 titian said:

Oh True : Missed that one.

Sounds like cooling is so good fans do not need to come on. If infact both work with diagnostic plugs connected.

One fan could be faulty. As no fan with aircon on

Why do you think it is overheating? Could be faulty indication on dash?

105C good temp for INLET to radiator (Upper Hose)

i only think its overheating cause of temp reading on my autogauge water temp meter.and i find it strange fans go on in diagnostics mode but not after a hours drive and bottom radiator hose isnt as warm as top hose ,is 105 C a good average water temp for top radiator hose? my factory water temp gauge does\'nt go above half way tho..this doesnt explain a semi cold bottom radiator hose when it reaches 105C..what do your guys aftermarket water temp gauges read.