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2001 Forester 4EAT
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Discussion Starter #1 (Edited)
Hello everyone! I wasn't sure where to post this, but I'm trying to diagnose an engine overheat issue on my '01 Forester which has 114K miles..
The car doesn't seem to be leaking oil externally and it doesn't seem to have oil in the coolant either.. I haven't yet done a block test to rule out the very likely HG issue since it may well be an electrical issue given that the A/C compressor and radiator fans turn on and off every 5 secs or so..
The car reaches operating temperature pretty quickly and then starts overheating.. So, I'm wondering if this could be from the radiator fans and A/C compressor not working properly? I'm trying to rule out the "less complicated" issues first before moving onto major work like the HGs change.
Thanks in advance
 

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2000 SF5 Automatic
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Let's see about some of those less complicated issues first.......
You didn't say if you're leaking coolant. I'll assume you are 😎

A crack at the seam between plastic and metal at the top of the radiator. Please look for this with a running engine.

Leaking hoses - top and bottom. Loose clamp? Brittle cracked hose?

A faulty / aftermarket thermostat.

Loose thermostat housing / bad thermostat housing to engine seal.

Worn out radiator cap.



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2001 Forester 4EAT
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Discussion Starter #5
Engine overheating.. trying to rule out electrical issue

I wasn't sure where to post this.. I'm trying to diagnose an engine overheat issue on my '01 Forester which has 114K miles..

The car doesn't seem to be leaking oil externally and it doesn't seem to have oil in the coolant either.. I haven't yet done a block test to rule out the very likely HG issue.

Wondering if the overheating may come from an electrical issue given the A/C compressor and radiator fans turn on and off every 5 secs or so..
The car reaches operating temperature pretty quickly and then starts overheating after 10-15 minutes of running.. I'm trying to rule out the "less complicated" stuff first before moving onto major work like the HGs change.

If anyone has any ideas what it could be, it'd be much appreciated.
 

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2017 Forester XT Touring CVT
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236 Posts
Let's see about some of those less complicated issues first.......
You didn't say if you're leaking coolant. I'll assume you are 😎

A crack at the seam between plastic and metal at the top of the radiator. Please look for this with a running engine.

Leaking hoses - top and bottom. Loose clamp? Brittle cracked hose?

A faulty / aftermarket thermostat.

Loose thermostat housing / bad thermostat housing to engine seal.

Worn out radiator cap
your right. @SubiAficionado do what they say then get back to everyone.

@bobk25 brings up all the easy and correct things to check first.
 

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2007 Forester Sports XT 4EAT
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You can bump up your thread once a day, which will get you more visibility, but there's no guarantee you'll get more replies. :confused:

Your thread has had over 150 views.

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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2011 Forester 2.5X Automatic
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186 Posts
...the A/C compressor and radiator fans turn on and off every 5 secs or so..
The car reaches operating temperature pretty quickly and then starts overheating.. So, I'm wondering if this could be from the radiator fans and A/C compressor not working properly? I'm trying to rule out the "less complicated" issues first before moving onto major work like the HGs change.
Thanks in advance
It sounds to me you have some issue with the cooling fan. Turn the AC off so it doesn't influence the operation of any fans. Start the car, warm it up and see if the cooling fan kicks on. The coolant is obviously getting hot enough so it should trigger the fan to come on. If the engine warms up and the cooling fan never kicks on then you have some electrical issues to pursue. The first is to check the fuse for the fan. Usually the high draw fuses are located in the engine bay ...look for a box off to the side or near the firewall; it might say "distribution box" or "electrical distribution". Pop the cover and you'll probably find a bunch of relays and some larger versions of the small amp fuses under the dash. The box cover should have a map of the fuses; find the one for the cooling fan and pull it. If the fan fuse is blown you've found your problem; replace and press on. Just for grins and giggles, check the fuse panel inside and make sure everything look good; use the map for the panel to see if there might be any cooling system related fuses. If the fuse(s) is/are good it might be the thermostat switch that will power the cooling fan at the proper temperature. Or, it could be the fan itself. To test the fan you'll need to make some jumpers to connect the power pigtail of the fan motor to 12V battery power. If, when you connect 12v to the fan, it runs, then you've probably got a bad thermostat switch for the fan.

With the AC fan, most of them only kick on when the AC compressor is engaged ...or maybe during an overheat condition but IDK about that ...just a guess.

Take care of the simple easy stuff first before you start having visions of blown head gaskets dancing in your head.
 

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2001 Forester 4EAT
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Discussion Starter #11
bobk25

Thanks for the reply.. I don't think it's leaking coolant but I'll double check tomorrow morning..

This is my very first Subaru ever, bought it used obviously, but I really like the car!
Previous owner changed the radiator cap, water pump, thermostat, and installed a Gates timing belt kit in an effort to fix the overheating problem, but the issue remains.

Engine oil is not dripping, but the left head(driver side) has "old" dried up oil underneath. I have things ready to take the engine out and do a complete overhaul, but that wouldn't make sense just yet when I'm still dealing with what seem to be an electrical issue. Which is why I'm first trying to figure out if the overheating is related to the radiator fans and/or the A/C compressor not working properly(maybe A/C lines are low on frion?), there's air in the cooling system do to an improper job before, has a bad relay, bad fan motor, bad temperature cooling sensor, or a bad head gasket itself.

From the research I've done looking at YouTube videos and such, many things can create engine overheating..

I just don't know where to start, which is why I requested the help of you guys..
 

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2001 Forester 4EAT
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Discussion Starter #12 (Edited)
jocko


I'll try checking the things you mentioned with the A/c off first and I'll see if I can also post a short video of things running to help diagnose it better. Thanks Mike!

ps: pardon my inexperience, but are both fans behind the radiator the cooling fans or is one the cooling fan and the other the A/C fan? Or is the A/C fan the one inside the car behind the dash?
 

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2000 SF5 Automatic
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On my car the AC fan is the one with smaller fins / blades behind the radiator

Check if the thermostat and cap are OEM.

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2001 Forester 4EAT
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Discussion Starter #14
If I’m not mistaken, standing in front of the car, the manual calls the left one: sub fan(A/C?)and the right one: main fan(rad fan?)
Not sure if thermostat is OEM, should I change it for an OEM one if it’s not? I know the rad cap is not
 

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2012 Forester 4 speed auto
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Pressure test the system

The first thing to do to check a cooling system is to pressure check it. You can borrow a pressure gauge from any auto parts store. Other than the fans there isn't much electrical temperature control in cooling systems. Since the temperature runs away from cold to overheating check any thing that can block the movement of coolant: thermostat, water pump, clogged radiator, etc. Good luck!
 

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2001 Forester 4EAT
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Discussion Starter #17
It sounds to me you have some issue with the cooling fan. Turn the AC off so it doesn't influence the operation of any fans. Start the car, warm it up and see if the cooling fan kicks on. The coolant is obviously getting hot enough so it should trigger the fan to come on. If the engine warms up and the cooling fan never kicks on then you have some electrical issues to pursue. The first is to check the fuse for the fan. Usually the high draw fuses are located in the engine bay ...look for a box off to the side or near the firewall; it might say "distribution box" or "electrical distribution". Pop the cover and you'll probably find a bunch of relays and some larger versions of the small amp fuses under the dash. The box cover should have a map of the fuses; find the one for the cooling fan and pull it. If the fan fuse is blown you've found your problem; replace and press on. Just for grins and giggles, check the fuse panel inside and make sure everything look good; use the map for the panel to see if there might be any cooling system related fuses. If the fuse(s) is/are good it might be the thermostat switch that will power the cooling fan at the proper temperature. Or, it could be the fan itself. To test the fan you'll need to make some jumpers to connect the power pigtail of the fan motor to 12V battery power. If, when you connect 12v to the fan, it runs, then you've probably got a bad thermostat switch for the fan.

With the AC fan, most of them only kick on when the AC compressor is engaged ...or maybe during an overheat condition but IDK about that ...just a guess.

Take care of the simple easy stuff first before you start having visions of blown head gaskets dancing in your head.
A few updates.. couldn’t do much since it was raining but started up the car this morning with the A/C system off and warmed up the engine to operating temperature. Didn’t have time to check Relays, but the radiator fans never came on, so there definitely seems to be issues with them.. Also noticed a considerable ammount of white smoke coming from the exhaust soon as I started the car, which reduced itself a lot after 2-3 mins of the engine running, but I guess that’s a clear indication the HG is bad also. Not sure if I mentioned the radiator was brand new, changed by previous owner, will pressure test cooling system as soon as I can. Thanks guys
 

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2001 Forester 4EAT
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Discussion Starter #18
The first thing to do to check a cooling system is to pressure check it. You can borrow a pressure gauge from any auto parts store. Other than the fans there isn't much electrical temperature control in cooling systems. Since the temperature runs away from cold to overheating check any thing that can block the movement of coolant: thermostat, water pump, clogged radiator, etc. Good luck!
Fans seem to be bad or not receiving signal to turn on when engine is at operating temperature. Also wondering if it could be be the coolant temperature sensor not sending a signal for the fans to turn on?
 

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Sorry about the rain. Did the temp gauge begin to move up before the fans fired?

I've just thought of something odd ... are the 2 fans running off the same power?? Somehow spliced together?


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2017 Forester XT Touring CVT
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If I’m not mistaken, standing in front of the car, the manual calls the left one: sub fan(A/C?)and the right one: main fan(rad fan?)
Not sure if thermostat is OEM, should I change it for an OEM one if it’s not? I know the rad cap is not

Yes Yes Yes, also radiator should be Genuine Subaru Part (OE). i had many after markets fail and one caused a really bad over heat.

The first thing to do to check a cooling system is to pressure check it. You can borrow a pressure gauge from any auto parts store. Other than the fans there isn't much electrical temperature control in cooling systems. Since the temperature runs away from cold to overheating check any thing that can block the movement of coolant: thermostat, water pump, clogged radiator, etc. Good luck!
if the system doesn't hold pressure when tested, then there is a leak some where.

take shop air and pressurized the system with 14psig of pressure and leave it on if you have a problems finding leak. pull spark plugs, if you have water in the cylinder. then head gasket. this is just a different way of finding a leak other then exhaust gasket in coolant test. perhaps there is more then one leak.
 
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