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Hello,

 

Long time 2.2 subbie owner - been in a 2.5 for about 9 months.  The 2.5 I am driving is a 99 outback (DOHC).  About 10-9,000 miles ago a subbie shop in town here changed the HG's, timing belt, t-stat, radiator, and all the associated parts with that maintenance.  The HG's were bad at this change and the heads were checked at a local machine shop (all OK).  

 

Last week (when the whole Nation was freezing cold) I was headed back from Portland (4.5 hour drive).  At about 3.5 hours into the drive I noticed my temp gauge was slightly higher than where it normally resides (It was only a few tick marks about the middle).  I found that if I accelerated (higher RPM's), it dropped to normal operating temp.  In the morning I finished my drive and noticed the same symptoms (lower RPM's and the temp would creep up just a bit, higher RPM's and the temp would reside in it's normal spot).  I finally had time to plug my scan gauge into it tonight and while fusing at highway speed (55 mph, 2,000~ RPM's) I would get a constant temp of 104-105 deg C, If I'd push a higher RPM it would drop to 100 deg C, or even get in around 97, 98, or 99 deg C.  Cursing through town it would ride at 105 deg C (25 mph) and sitting parked in my driveway it would ride back down to 97 deg C.  Both radiator fans are running just fine.  

 

Any thoughts?  HG's, again?  T-stat?  Was it the single digit temps that pushed it over?  105 deg C is too warm for me, hope it's not too warm for this car.  It bounced up to 107 deg C briefly and returned to 105.  Thanks in advance.    

 

177K on this engine, HG's changed about 10K ago (heads checked too)

  

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That's not dangerously high, you didn't hurt anything running 107 for a minute or two. When it heats up, does the heater stop blowing hot air at all?

Do you get bubbles in the overflow tank?

 

Also, any idea what thermostat the shop installed. If it wasn't a subaru OEM one, it's junk and probably what's causing your problem.

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That's not dangerously high, you didn't hurt anything running 107 for a minute or two. When it heats up, does the heater stop blowing hot air at all?

Do you get bubbles in the overflow tank?

 

Also, any idea what thermostat the shop installed. If it wasn't a subaru OEM one, it's junk and probably what's causing your problem.

The heater blows hot air all the time.

 

I didn't see any bubbles when I checked previously, but tonight it was getting too dark to look.

 

The non-OEM t-stat was something I was going to check.  They 'said' they put in subbie parts, but I didn't see it before it went in.  Depending if I can get one tomorrow I planned on checking that just because that's the cheapest route!  I have a used one that I swapped in from '96 2.2 years ago (routine) that has been sitting in the box…does anyone know if the 2.2 and the 2.5 are the same t-stat?  

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The heater blows hot air all the time.

 

I didn't see any bubbles when I checked previously, but tonight it was getting too dark to look.

 

The non-OEM t-stat was something I was going to check.  They 'said' they put in subbie parts, but I didn't see it before it went in.  Depending if I can get one tomorrow I planned on checking that just because that's the cheapest route!  I have a used one that I swapped in from '96 2.2 years ago (routine) that has been sitting in the box…does anyone know if the 2.2 and the 2.5 are the same t-stat?  

 

Yes, they're the same. That one will work fine.

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I happen to use a Scangauge II on my 96 2.5 so I can provide some data as reference. My Outback has a well-functioning cooling system (3-year old OEM radiator, 1-year old OEM thermostat, OEM HG and water pump done 1 year ago). My Scangauge shows water temp 84-87 C when cruising on highway. Anywhere between 86 - 97C in stop-and-go traffic. It reaches 95-97 only when the car is idling for more than 2 minutes. Never reaches 95 when the car is moving faster than 30 MPH, both summer and winter. As soon as 95 C is reached, the radiator fans kick in and bring the temp down to 86-87 in about 1 minute, even in a hot 90 (F) degree day. I don't know how bad 105 C is but it's certainly not normal. Good luck in fixing your problem.

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I happen to use a Scangauge II on my 96 2.5 so I can provide some data as reference. My Outback has a well-functioning cooling system (3-year old OEM radiator, 1-year old OEM thermostat, OEM HG and water pump done 1 year ago). My Scangauge shows water temp 84-87 C when cruising on highway. Anywhere between 86 - 97C in stop-and-go traffic. It reaches 95-97 only when the car is idling for more than 2 minutes. Never reaches 95 when the car is moving faster than 30 MPH, both summer and winter. As soon as 95 C is reached, the radiator fans kick in and bring the temp down to 86-87 in about 1 minute, even in a hot 90 (F) degree day. I don't know how bad 105 C is but it's certainly not normal. Good luck in fixing your problem.

I had a chance to work on the car today.  Problem fixed.  It was the t-stat.  It was one of those crap aftermarket ones.  I could tell as soon as I removed the t-stat bracket (no air passage 'float valve') and even more when I pulled it out (short, copper, lightweight spring…garbage).  I really don't understand why the aftermarket company even makes this garbage AND I don't understand why the shop who I got the car from even claims they use 'genuine Subaru parts'.  I have a shop in Eastern Oregon I know I won't use anymore.  

 

The thing I wonder is for nine months that car has been running 'hot' (104 deg C).  Makes you wonder how long it could of held it up, not that's I want to find that out either!  

 

Vasy:  Thank you for the report.  My numbers are similar, now.  

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You didn't really overheat it, so I doubt it. Unless they used bad quality gaskets or did poor work. But you caught the thermostat thing before any harm was done.

+1 to my OCD, eh?  Well good, it finally paid off!  I won't gloat it too much, my wife will get sick of it fast.

 

Just curious, what temp constitutes overheating?   

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Anything above 200 while driving usually raises alarm to me. like 230 or 240 is when you probably want to shut it down before harm is done. The coolant temp is less important than the oil temp, really. Because when the oil overheats it gets less viscus causing low pressure means bearings get screwed.

If the temp spikes and you shut it down fast, chances are you didn't have a chance to overheat the oil and do any serious damage. Though I'll usually change the oil after such an event.

 

An oil temp gauge is an important metric to engine health. Because if you see coolant temp spike, but oil temp doesn't move much, you're OK. If you see the oil temp spike and coolant kinda meanders up, yea, it's done for.

Edited by 987687
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