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2006 OutBean, 2005 LGTW
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Discussion Starter #681
That tiny heater core is also not near a heat soaked engine, already at 200*F, as well as getting ambient air blowing through it. One thing this sort of brings up, is your A/C over charged? I wonder if your system is over charged creating extra drag/pressure on the pump as well as making the condenser more hot then it needs to be, causing more hot air to run over the radiator. Although I havnt seen over charged ac systems cause a problem before(Lived in Phoenix, was super common to over charge systems so passengers could actually be cool in 120*F weather).
That's a curious thought. I have gauges but I don't know what I'm doing with them. I'll put in some effort to figuring it out though.
 

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2005 Outback VDC limited 3.0r
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That's a curious thought. I have gauges but I don't know what I'm doing with them. I'll put in some effort to figuring it out though.
There should be a chart in the fsm. There is also generic ones for ambient temps and humidity for what your pressures should be at, for a rule of thumb
 

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2001 VDC/SC One of a Kind
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FWIW, My Autel reads the alternator duty the same as RR; 0%. The alternator voltage varies with engine rpm. Low rpm results in low voltage and the duty cycle continues to show 0%. I've not seen it on any H6 I've had in the shop or otherwise that the duty cycle was other than naught.

Those temps look good to me. It doesn't stay high too long and it's below the 225 "oh shite" mark. If it continually approached temps of 225 or higher, there's a definite problem.
 

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I don't see Alternator duty listed in the FSM as a parameter available from the 2006 H6 ECU. [EN(H6DO)(diag)/Subaru Select Monitor/READ CURRENT DATA FOR ENGINE (NORMAL MODE)]
I erred in post #675 (quoted above), having originally searched for keyword "alternator". In fact, there is an entry in the FSM table of parameters shown as

470858
 

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I really doubt it's the sending unit. My money is on the radiator.
Sorry for the delayed response. Work has me out of town mostly, but..... I checked the rad and its clean. Then when I had some time changed the thermostat..... SAME ISSUE like you have. Not sure what steps to take at this point.
 

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I don't know a lot about cars but what if the coolant circulation is affected just by the action of being pointed upwards at a steep incline? Would that have any affect on coolant flow through the radiator? Gravity is nothing to sneeze at

Edit: Alternatively, how does being pointed upwards affect oil travel through the engine?
 

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normally, there's little or no air in a car's coolant system so, hydraulics wins over gravity.

oil, there is enough volume, as well as baffles, pick-ups and 'windage trays', etc. to help assure the pick-up is always submerged. In racing, or in acrobatic aircraft, vectored forces mean a closed system or other adjustments to oiling system design is needed.
 

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I have never had to put the engine "up" when burping a system. All the cars I've done were level. It's a matter of getting the coolant to move through the heater core and pushing the air out of it. I rev the engine up to 4k rpm a few times and this gets it done.
 

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Discussion Starter #689
Sorry for the delayed response. Work has me out of town mostly, but..... I checked the rad and its clean. Then when I had some time changed the thermostat..... SAME ISSUE like you have. Not sure what steps to take at this point.
You have to remind me.. did you have the "overheating" issue before? I forget your issues...
 

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@aesthetic.rake, I wasn't able to find the reason in the previous thread pages, but what was your verdict on suspected water pump failure? My own overheating has returned, along with coolant loss and pitiful heat from the heater core. I spotted my radiator leaking, so I was going to replace that, but I wonder if my water pump is going as well. I'm really hoping not because I don't want to have to replace it.
 

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@aesthetic.rake, I wasn't able to find the reason in the previous thread pages, but what was your verdict on suspected water pump failure? My own overheating has returned, along with coolant loss and pitiful heat from the heater core. I spotted my radiator leaking, so I was going to replace that, but I wonder if my water pump is going as well. I'm really hoping not because I don't want to have to replace it.
Iirc he replaced it as just a possibility. We(He) still haven't figured out the overheating problem. I would start with replacing your leaky radiator as your first start. Instead of trying to diagnose a problem that isnt there, yet. Then from there, you can continue to diagnose.
 

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Iirc he replaced it as just a possibility. We(He) still haven't figured out the overheating problem. I would start with replacing your leaky radiator as your first start. Instead of trying to diagnose a problem that isnt there, yet. Then from there, you can continue to diagnose.
I went ahead and replaced the radiator with a Spectra radiator, installed new upper hoses, lower hose, and worm-drive hose clamps. I then filled the system with plain distilled water and burped it as best I could. Strangely enough, I get the same foaming/microbubbles after revving a bit to burp the system. Not a hint of an exhaust smell. I felt the lower radiator hose after about 10 minutes of burping the system and coming up to operating temp, and it didn't have much pressure. It was also less than lukewarm. Worrying.

Sure enough, on my test drive to work today, it started overheating again. Not nearly as much as before (where I almost reached the red zone), but still concerning. I think, sadly, that replacing the water pump will be my next step.

It's strange how closely my issues mirror yours.
 

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2008 JDM Outback 3.0R, 5EAT
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I felt the lower radiator hose after about 10 minutes of burping the system and coming up to operating temp, and it didn't have much pressure. It was also less than lukewarm. Worrying
Mine did the same after a recent radiator replacement, lower hose didn't get hot until after a drive.
 

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It stayed less-than-warm even after driving to work, sadly.
Did you have the front end up in the air, or a spill free funnel on? You need to get the nose up higher then the heater core to get air out, at least that's the best method I have found.
 

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Did you have the front end up in the air, or a spill free funnel on? You need to get the nose up higher then the heater core to get air out, at least that's the best method I have found.
Yep, front end was still plenty jacked up, along with a spill-free funnel unfortunately.
 

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Discussion Starter #698
Okay.. I'm a bit drunk this evening but I'm going to do my best to address this.

I don't think it matters how much you jack up the front of an h6 subaru, the high point will almost always be the throttle body so if you want to bleed air, that's the first place I'd start.

@joe r posted a link that gets it mostly right--removing the heater hose is a good start but filling from the heater hose is god tier h6 coolant system bleeding. The problem is air gets trapped behind the thermostat and, well, you don't get any heat, nor do you get coolant flowing through the radiator because the thermostat isn't opening.

If you're not getting heat or the thermostat isn't opening, one of two things is going down. Either there's an air pocket behind the thermostat preventing coolant from traveling unimpeded or you've got a blown headgasket that is pushing exhaust gases into the system and they're collecting at the thermostat. No heat seems to indicate air pocket.

Okay, so how to get the air out of the system.

First--fill through the either of the upper radiator hoses or the upper most heater hose. The point would be to put as much coolant behind the thermostat as you can. If you pull, say, the passenger radiator hose and fill through it, the system will fill up until coolant flows out of the radiator. At this point you know the system is mostly full. Install the radiator hose and start the car. Once the car is running, you'll need to squeeze the lower radiator hose and force fluid from the radiator side through the jiggler pin on the thermostat and into the water pump. I have a vacuum coolant filler and I STILL have to do this. You'll get tired of squeezing but don't let up until your lower radiator hose is hot.

After the lower hose is hot, that's the time to pull the hose leading off the throttle body. You'll find all kinds of air in there. Once you get a fairly steady stream of coolant from the hose, reinstall it and keep up on the bleeding. You're going to need a coolant funnel--there's just no way around it. As the engine cycles in temps, the coolant within thermally expands. Without a coolant funnel, it'll just leak all over until it gets cool again and you'll think it has run low on coolant and it becomes a vicious cycle of adding and losing coolant.

Everyone tried to warn me the water pump was the least of my worries but I wouldn't listen. I cost myself a considerable amount of money and time swapping it out and it was not at all the issue. I suspect you'll find yourself in the same boat so do NOT replace the water pump. It's not the cause of your issues. Once you get heat and the lower radiator hose hot, we'll talk about alternatives to your problem.

You have an air pocket. You have all the symptoms of an air pocket. The H6 but Subarus in general can be a pain in the ass to get air out of the system. Work the air out definitively.
 

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@aesthetic.rake, thank you for the detailed reply. Just to make sure I've got it down, I'm going to perfect this bleeding procedure with just distilled water at first. As for the hose "leading off the throttle body," you're talking about this one
this one

right? Won't I have water (and later coolant) gushing out of that hose once the air is out? I want to be prepared for that scenario so I'll probably stick a catch pan underneath.
 

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Discussion Starter #700
That's your
@aesthetic.rake, thank you for the detailed reply. Just to make sure I've got it down, I'm going to perfect this bleeding procedure with just distilled water at first. As for the hose "leading off the throttle body," you're talking about this one
View attachment 474036
right? Won't I have water (and later coolant) gushing out of that hose once the air is out? I want to be prepared for that scenario so I'll probably stick a catch pan underneath.
That's your upper radiator hose.

I wouldn't bother "practicing" filling up the system with distilled water because it'll be a crap shoot on whether you bleed it correctly or not. You don't want to spend an hour bleeding the thing just to turn around and drain the system to re-bleed it with coolant in it.

The throttle body is up near the big black plenum at the back of the engine closest to the firewall coming from your air cleaner. There's a hose on the drivers side, toward the top, with a spring clap on it--that's the coolant hose leading from your throttle body.

Don't even bother with any of that though.. In the picture you posted above, pull the radiator hose off the radiator on the passenger side of the engine and pour coolant into the block from that hose until it comes pushing out of the hole in the radiator. Once coolant has filled the system, put the hose back on and start the car. Keep working that lower radiator hose, forcing water through the jiggler pin until you force the air behind the thermostat into the water pump to be cycled out.
 
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