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2010 Forester XT 4EAT
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1,123 Posts
Discussion Starter · #1 ·
I have the manual HVAC controls. So over the winter my blower motor started not working on a couple of speeds and then working and not working and doing that for awhile. I ordered a new oem resistor and never got it installed yet. I know this might sound like a dumb question, but I swear somewhere I read said this could also cause the engine to overheat. Today after waiting in a long drive-thru, I was on my way home and the temp light came on briefly. I was only about 3/4 of a mile from home and I turned the climate control temp to hot and it went off and stayed off then the rest of the way home. Of course I couldn't use the blower. I waited for the car to cool down, checked the coolent and it's full, the radiator is new (was installed last year and no leaks) and I checked the main fan and sub fan fuses under the hood and they are both good. I started the car again and turned the AC on and the fans both work. So I'm going to replace the blower fan resistor inside the car tomorrow, but it doesn't seem like that would be related, or is it?
 

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2011 Subaru Forester
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1,373 Posts
It can help evacuate a bit of the surplus heat, but the blower motor is not the cause of the engine overheating.
Hopefully it's a sticking thermostat rather than your head gasket.
 

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Super Member
2010 Forester XT 4EAT
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1,123 Posts
Discussion Starter · #4 ·
Blower motor has nothing to do with engine temps.
That's what common sense was telling me! Thanks.

It can help evacuate a bit of the surplus heat, but the blower motor is not the cause of the engine overheating.
Hopefully it's a sticking thermostat rather than your head gasket.
I hope you're right! I've never seen any evidence of any head gasket failure. Nothing visible on the engine, coolent is full and clean, oil isn't milky and nothing under the cap. Also not blowing any smoke at all. When we did the radiator we did not change the thermostat so I will do that. Hopefully that's not too hard.
 

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2018 Forester Limited
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400 Posts
When we did the radiator.....
I think there's a back story here, so let's discuss. Why? How long ago? Radiator model and source?
 

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Super Moderator
2001 Forester S, 4EAT
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2,923 Posts
@markyh How many miles on the engine? HG issues do not always show up as milky oil. HG issues symptoms include:
  1. Milky oil (coolant mixing with oil)
  2. Coolant loss related to #5
  3. Oil leak related to #5
  4. White Exhaust (Coolant being burnt)
  5. Signs of leaks under the engine where the HG seam is located on the engine.
  6. Exhaust gas detection kits for coolant.
  7. There maybe other symptoms
 

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Super Member
2010 Forester XT 4EAT
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1,123 Posts
Discussion Starter · #7 ·
I think there's a back story here, so let's discuss. Why? How long ago? Radiator model and source?
I have a 2010 XT and the radiator which is mostly plastic busted. When we replaced the radiator I asked my friend if we should replace the thermostat and he said to wait until it goes bad and again my better judgement, I went with him on that.
 

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Super Member
2010 Forester XT 4EAT
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1,123 Posts
Discussion Starter · #8 ·
@markyh How many miles on the engine? HG issues do not always show up as milky oil. HG issues symptoms include:
  1. Milky oil (coolant mixing with oil)
  2. Coolant loss related to #5
  3. Oil leak related to #5
  4. White Exhaust (Coolant being burnt)
  5. Signs of leaks under the engine where the HG seam is located on the engine.
  6. Exhaust gas detection kits for coolant.
  7. There maybe other symptoms
I have none of those symptoms.

I have a 2010 XT with just under 60K miles and everything is in great shape, but I can't fight time and weather, so things are aging and just starting to go bad. The general consensus is that plastic Subaru radiators fail about the ten year mark which is exactly what mine did. Now a year later I have a temp light come on when driving home from a drive-thru and after turning on the heat it went out and I didn't even fix my blower motor resistor yet. I'm 99% positive it's the thermostat now since I've checked everything else. I just totally forgot it hadn't been changed until now.
 

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2017 Forester XT Touring EyeSight
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722 Posts
Blower motor has nothing to do with engine temps.
This is essentially, but not literally, true. The heater is capable of removing heat from the engine, and can do that maximally if the blower is working. Less so if it's not. That is not "nothing". But this is a silly line of thinking, because the rest of the cooling system of the car, when functioning properly, can handle all the heat removal needs of the engine in all conditions, whether the heater is working or not. ;)
 
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