# Overheating problems with Subaru

**URL:** <https://community.cartalk.com/t/overheating-problems-with-subaru/67027>\
**Category:** Maintenance/Repairs\
**Created:** [August 11, 2011, 11:55am UTC](https://community.cartalk.com/t/overheating-problems-with-subaru/67027 "2011-08-11T11:55:18Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![eeatuc](https://avatars.discourse-cdn.com/v4/letter/e/aca169/32.png) [@eeatuc](https://community.cartalk.com/u/eeatuc)\
**Post date:** [August 11, 2011, 11:55am UTC](https://community.cartalk.com/t/overheating-problems-with-subaru/67027/1 "2011-08-11T11:55:18Z")

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Has anyone faced a similar overheating problem with a Subaru Legacy?

Symptoms:

- Started ~9 months, 5-10k miles ago
- Enging overheating at higher engine loads (either speeds \> 60mph or longer uphill stretches)
- temperature gauge goes beyond center towards the red area, ECU reading confirms temperature going beyond 105C (I never went beyond 110C before taking action)
- in such situations, reducing speed and putting heating on full blast cools down the engine in a few minutes to nominal
- behaviour strongly dependent on outside temperature,  
e.g. on a cold winter day going 90-100mph is no issue,  
on hot days with AC on, 45mph can already be a problem.  
This makes it difficult to decide whether problem is becoming worse over time.

Problems considered so far:

Fans:

- ECU reports fans switching on
- visual check confirms both fans are running  
Head Gasket:
- no obvious oil in coolant
- no obvious coolant in oil
- mechanic tested twice with sniffer for exhaust in coolant (negative)
- no significant loss of coolant  
Radiator Cap:
- cleaned and shortened reservoir hose according to Subaru TSB -\> no change
- replaced radiator cap -\> no change  
Thermostat:
- mechanic replaced thermostat -\> no change  
Collapsing hose:
- hoses appear firm and in good condition  
System not properly “burped”:
- radiator flushed and refilled by mechanic -\> no change.  
Thermal sensor broken:
- measured engine block temperature near thermal sensor location and it is close to ECU read-out  
Water pump:
- how to check best?  
Radiator (currently my prime suspect):
- lower hose is hot
- difficult to check radiator temperature by hand since fans and AC heat exchanger block access.
- checked the temperature on the left and right edge of radiator and it appears substantially coolr at bottom end  
actually it feels cooler than lower radiator hose
- how can one check whether the cooling capability of the radiator is degraded?  
Crack in engine block:
- hairline crack that only opens when engine is hot?
- how can one check this?

Any recommendations or suggestions would be great.

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**Author:** ![mcparadise](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mcparadise/32/32_2.png) [@mcparadise](https://community.cartalk.com/u/mcparadise)\
**Post date:** [August 11, 2011, 1:06pm UTC](https://community.cartalk.com/t/overheating-problems-with-subaru/67027/2 "2011-08-11T13:06:28Z")

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Year, mileage, and engine size/type please. Not all Subaru Legacys are the same.