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TL;DR Radiator is verified functional. OEM radiator cap is new and functional. OEM thermostat is verified functional. Heater core flows water well and can cool ECT. There appears to be no discernible blockage in the engine itself including the oil cooler circuit. Both upper (L & R) and lower radiator hoses are new. The entirety of the cooling system holds pressure appropriately. Fans verified functional and work as intended. Engine overheats with an increase in RPM regardless of load. Idles fine without overheating even with high ambient temps although the fans and their ability to cool the system seems lazy. Engine coolant burped appropriately with no air pockets in the system. No tail-tell signs of headgasket failure including loss of coolant or bubbles in the radiator or overflow even after heavy load runs and high ECT (222°.) All signs seem to point to the last piece of the cooling system--the water pump--and it's distinct lack of flow/pressure.

For those interested...

I haven't been able to solve this over the last two weeks I've been fiddling around with the car but I'm beginning to have an idea about what the problem could be. I come here asking for your help and guidance, because what I'm thinking the problem could be isn't a typical problem, meaning, I have yet to find this issue documented anywhere on the internet. Let me take you through it..

Background: The car doesn't overheat in the traditional sense. It hits the 3/4 mark on the gauge, so, really, it's just running hot. The hottest temps I've recorded on my OBD2 reader is 233°. This was a very steep uphill with ambient temps ~104° with my foot buried in it, trying to get the car to overheat. It's an 06 Outback LLBean 3.0r with ~203k miles. We bought the car knowing it overheated and that two Subaru dealerships and three independent mechanics have looked at the car and haven't been able to figure out why it's running so hot. The issue started at ~175k miles and the previous owner had a new radiator installed by his mechanic which did not fix the issue. We bought the car at 200k miles.

Symptoms: In the cooler months, the car is fine. Run it hard, run it uphill, race the engine, no worries. Ambient temperatures above 85°, say, and the overheating starts, but only under certain conditions. The car runs fine around town and doesn't exceed 210° even sitting at an idle when it's 107° outside and the AC is running full blast. Originally, I thought just running the car uphill on a hot day was the only way to get the car to overheat but the other day I discovered a new way. As it turns out, running the car at higher RPMs will cause the overheat as well, regardless of load. Uphill, flat land, downhill, whatever--pick up the RPMs to 3k and above under any conditions using the sportshift and the temperature starts climbing.

I've flushed out this motor 7 or 8 times now. I've used compressed air and house water pressure (~75psi) to blow out anything I can get to--the oil cooler water line, the heater core outlet line, the heater core itself and whatever else I could think of looking for a clog. I've pulled the (new) radiator out and flushed it as best I could using a water hammer technique. I've water hammered the heater core itself and verified water flows through it freely. The new and old thermostats have been tested and verified functional on the stove with two different thermometers, just to be sure. Both upper radiator hoses and the lower hose have been replaced as they felt a little soft/spongy and I was concerned the suction side of the water pump was making the lower hose collapse under high RPMs. I've found nothing.

I've verified the radiator isn't clogged yesterday after removing it to flush it out. The exterior was free of debris. The AC condenser is unimpeded as well. I reinstalled the radiator without the fans to gain easy access to the back of the radiator and while running the car to temp, I used an infrared thermometer looking for temperature variations across it's surface--the radiator is perfectly functional. The PO's mechanic changed the radiator, but not the cap (even though the PO was charged for it) which I replaced last week with a new Subaru part. The old cap wouldn't keep pressure in the system and during my first overheat, the coolant blew out of the radiator overflow tank. The new cap solved the blowing coolant out of the overflow issue, but not the overheat. At this point, I pressure tested the entire cooling system with a rented tool from Autozone. The system held pressure appropriately, even overnight. The thermostat is a new Subaru part as well. Both cooling fans are verified functional. The fan with the controller was just replaced as I thought it wasn't kicking up to high speed so with the new controller and fan, I'm able to verify the fans function at all 3 speeds and come on under their designated conditions (mid temp, mid temp and AC, high temp and AC, etc.)

The headgaskets are not blown. The PO had the car tested with both the chemical test and the spectrum analyzer machine both of which came back negative. Besides these tests, I can personally verify that there are no bubbles in the coolant system from exhaust gases at any point. I have pulled over with the temp gauge at the 3/4 mark and the live data reading 222° and popped the overflow tank cover to verify, not a single bubble coming through. The engine uses or loses no coolant. There is no water intrusion into the oil or any other signs of the headgaskets being breached.

Verifying the coolant system is functional and working as intended, this leaves two potential issues. Tune (AFR, plugs, valve lash, Air intake system, etc) which I'm ruling out at this point as the car runs well and.... ready for it?? Water pump.

Now, the water pump has not failed in the typical sense. I understand that Subaru water pumps are extremely robust and that there are zero references that I've been able to find about a H6 water pump being bad or faulty. It's not leaking coolant. The bearings aren't making noise. I've removed the thermostat and reached into the housing to feel for play on the backside of the water pump and nothing feels loose or abnormal. Using an inspection mirror and a flash light I've looked at the blades on the water pump itself and all seems well. This visual inspection however, I feel is problematic. It wouldn't take much erosion on those blades to lose efficiency of flow. I believe the pump itself is original as I've found no reference to it being changed in any of the service history I have. Even when the timing chains and tensioners were replaced at 195k, which would have been an ideal time to replace the water pump, there's no mention of the part or of it being discussed (even though there was a documented discussion of having the head gaskets done due to this particular overheating issue, which was declined by the PO.)

To test the water pump theory, after I flushed the radiator, I decided to refill the system with just tap water. (I know.. but I'm tired of spending $ on coolant and distilled water and really, with this test, I had little way to contain the mess it was about to create so tap water was the most friendly thing I could use.) I started the engine and pulled the heater core outlet hose. Water sort of.. dribbled out. It occured to me though that I was introducing air to the back side of the water pump by removing this hose so I rigged up the garden hose to "refill" this hose (without pressurizing it) and tried again. At this point, there was actually some flow from the heater core. Not as much as I expected there to be but it was increased greatly from the previous test. Putting my finger over the heater core outlet, I noted the distinct lack of pressure created by the water pump. The car is just idling however and being the electronic throttle control type, I was unable to rev the motor and feel for pressure at the same time. Lucky for me though, my wife was just pulling in the driveway. With her help revving the motor, I was able to see the flow increase, or lack thereof from the heater core outlet. It appears to me the water pump isn't flowing very much water.

Subaru offers a water pump discharge performance rate specification in the FSM (CO(H6DO)-2 for those interested) of 84.5 gallons per minute. At 5,500 rpms and engine coolant temps of 176°, ~25.5 psi of discharge pressure. Now, I don't expect to get 84.5 gallons per minute out of the 5/8" heater core outlet tube but what I got was more in line with -maybe- 5 gallons per minute, if that. With the rest of the system closed off, putting my finger over the outlet tube I felt little pressure--even with my wife on the throttle both steadily and goosing the throttle. I really don't think the water pump is moving as much water as it should. I'm considering building a rig to test the pressure and I'd love to be able to test the flow rate but I haven't been able to figure out how to do it accurately. A simple test we did was after bringing the car to operating temperature, I put some gloves on and squeezed one of the upper radiator hoses while my wife revved the motor. I felt very little pressure increase which again points to a water pump that isn't moving water as it should.

And if you think about it, it kind of makes sense. High engine RPM with little or no load increases ECT. High engine RPM with a high load (like a steep hill) increases ECT enormously. Higher RPM would obviously increase ECT but that increase should be offset by an increased flow rate from the water pump through the cooling system. The car idles and drives around town fine even with very high ambient temperatures and AC on full blast but race the motor at all and the ECT jumps up.

Now, before you say "Air Pocket in the cooling system," I want you to know I've developed a technique for filling the cooling system on this car that seems fairly fool proof. I fill from three different locations-- First, the output tube on the heater core, which fills the heater core itself, the engine oil cooler and up to the back side of the thermostat-- Second, the heater core outlet hose (which is the opposing side of the tube filled previously) which completes the coolant circuit to the backside of the thermostat and water pump and finally-- the radiator neck until coolant flows out from the heater core outlet itself in which I reattach the heater core outlet hose to the tube. Following this procedure, I see very few air bubbles come out of the system and into my spill free funnel. Running the car to operating temp, I verify the thermostat has opened by the temperature of the lower radiator hose and lack of bubbles coming into the spill free funnel.

Thoughts?? The water pump isn't very expensive but will be a bear to get to and I'd like to get your feedback before tearing into it and potentially wasting any more time or effort.

Thanks
 

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coupla ideas;

run with thermostat removed, I THINK the 'jiggle' pin must be oriented to the front of the car(? anyone?)

bypass heater core with appropriate tube and hose combination.

do temps come down if you blast the heater on full?

how's the transmission fluid look?

fans are weird on these cars - they have a hi and low speed, but I doubt that would have any effect above 20mph.
 

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Discussion Starter #3
coupla ideas;

run with thermostat removed, I THINK the 'jiggle' pin must be oriented to the front of the car(? anyone?)

bypass heater core with appropriate tube and hose combination.

do temps come down if you blast the heater on full?

how's the transmission fluid look?

fans are weird on these cars - they have a hi and low speed, but I doubt that would have any effect above 20mph.
Thermostat removed: Done and no difference. Car still gets hot which indicates a lack of coolant flow. Thermostat, when installed, is correctly oriented with jiggle pin @12 o'clock position
Heater core: not clogged and free flowing
Temps w/ heater: Yes, heater can remove heat from system
Trans fluid: Okay. Transmission doesn't trigger "auto trans temp."
Fans: 3 speeds I believe. The system can run 2.5v, 5v (with test mode connectors plugged in) and 12v for full power.
 

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does the use of the heater make a dramatic difference? that 'might' indicate an airflow issue.

if you encounter high temps driving, and were to shift to 3rd, would temps come down? that 'might' point to coolant flow.

here's an inline pump - maybe there is an appropriate one for your car? could be easier than a new WP !


http://www.stewartcomponents.com/index.php?route=product/category&path=63

 

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Discussion Starter #5
does the use of the heater make a dramatic difference? that 'might' indicate an airflow issue.

if you encounter high temps driving, and were to shift to 3rd, would temps come down? that 'might' point to coolant flow.

here's an inline pump - maybe there is an appropriate one for your car? could be easier than a new WP !


Stewart Components

Use of the heater doesn't make a dramatic difference. You wouldn't notice it on the gauge. Live data shows it but it's not that significant. The airflow through the AC condenser and radiator is unimpeded meaning-no bugs or debris build up on or in between the condenser and radiator. The fans pull significant air through both easily.

Raising the RPM's increases temperature regardless of load. Shifting to third gear, from say, 5th gear, at 45 mph, increases the ECT significantly--even going downhill.

I had considered an add on pump and thanks for the idea as well. A new Subaru pump is 115 and change. For the difference in costs I'll turn wrenches for weeks lol
 

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Could the gauge be inaccurate?
Any electrical issues or past history of failed alt/short/fuses/battery compromised?

1. Does it do the *exact same thing* every time you drive it? or does it vary somewhat and come-and-go?

2. Has the engine ever had prior work done to it before you owned it?
Engine swap?
Have the timing covers ever been removed?

3. Is night and day different temp characteristics? Reduced cooling capacity should result in better performance during lower temps (night).


The most likely Subaru H6 scenarios are:

A. the radiator isn't fully flowing.

how did you verify it's flowing properly?

Are Subaru internal radiator passages "in series" or "in parallel"? the only one i've ever taken apart to see the insides of i'm almost positive was in parallel. is it possible it's flowing decently enough to pass a highly variable/imprecise garden hose test, but all the cavities and surface area aren't being utilized within the radiator?

with a temp gun maybe you could monitor surfaces temps with the radiator off the car and cold hose water to see if the surface cools uniformly?

*** maybe you could try it on the car but i've had a hard time getting good radiator/condensor readings on a subaru due to access and heat convection all over the place.

the heater core hose test doesn't sound compelling to me...be ideal to compare it to another subaru.

B. headgaskets - H6 headgaskets are notoriously hard to catch in the initial stages - they will quite literally pass every test known to man and they only fail intermittently...and as such overheat intermittently. they won't "always" have bubbles or "always" overheat or "always" be symptomatic at first. then after a certain point they progress and the symptoms are more obvious every time but by then it's usually obvious to someone as well eyed as you are. since yours seems to always do the same thing the headgaskets seem unlikely.
 

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how long were you running that odd ball ford motorcraft "thing" in there instead of a proper subaru thermostat?

same for the rad cap?

I hope those 2 things did not ruin a otherwise good engine.

_______

that ford dealer should have its licesene to do business revoked,

the big easy fix could be a JDM EZ30 250hp engine. (the one with the plastic intake, vs. the older 212 hp metal intake variety).
 

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Discussion Starter #8
Could the gauge be inaccurate?
Any electrical issues or past history of failed alt/short/fuses/battery compromised?

1. Does it do the *exact same thing* every time you drive it? or does it vary somewhat and come-and-go?

2. Has the engine ever had prior work done to it before you owned it?
Engine swap?
Have the timing covers ever been removed?

3. Is night and day different temp characteristics? Reduced cooling capacity should result in better performance during lower temps (night).


The most likely Subaru H6 scenarios are:

A. the radiator isn't fully flowing.

how did you verify it's flowing properly?

Are Subaru internal radiator passages "in series" or "in parallel"? the only one i've ever taken apart to see the insides of i'm almost positive was in parallel. is it possible it's flowing decently enough to pass a highly variable/imprecise garden hose test, but all the cavities and surface area aren't being utilized within the radiator?

with a temp gun maybe you could monitor surfaces temps with the radiator off the car and cold hose water to see if the surface cools uniformly?

*** maybe you could try it on the car but i've had a hard time getting good radiator/condensor readings on a subaru due to access and heat convection all over the place.

the heater core hose test doesn't sound compelling to me...be ideal to compare it to another subaru.

B. headgaskets - H6 headgaskets are notoriously hard to catch in the initial stages - they will quite literally pass every test known to man and they only fail intermittently...and as such overheat intermittently. they won't "always" have bubbles or "always" overheat or "always" be symptomatic at first. then after a certain point they progress and the symptoms are more obvious every time but by then it's usually obvious to someone as well eyed as you are. since yours seems to always do the same thing the headgaskets seem unlikely.
There have been no electrical issues that I'm aware of. Everything seems to work corrrectly.

I wondered about the ECT sensor. The heater blows within 10° of what the OBD2 reader is reading from the ECU. I pulled the sensor, cleaned it up real well and took an ohm reading. I can't remember where I found it online but I managed to find some ohm numbers for a given temperature and the sensor seemed to be inline or pretty close. The heater core blows within 10° of what the ECU says is the temp and the infrared thermometer reports close to the same temp when pointed at the area around the sensor. I think it's fairly accurate.

The ECT varies by ambient temperature but it's generally the same thing with no randomness. I can repeat the overheat consistently, provided the ambient temps are high enough. In the winter, when the weather is in the 60's, the cooling system has the capacity to keep the engine cool regardless of revs or how it's driven. It's easier to keep the car cool in the evening than it is during the day, to answer your question about it specifically.

The timing covers have been removed at ~195k miles when the car threw a code- timing bank 1 too advanced or something. The mechanic verified the car had jumped time "One tooth" and they installed new tensioners, guides and chains. The PO asked, or the shop tried to sell the PO on removing the heads for gaskets, due to the overheating, but the PO declined. They buttoned it back up without doing a water pump and we purchased the car shortly thereafter.

I pulled the radiator and fans to flush out the core as best I could. My hose didn't put out much flow but the radiator was more than capable of moving the volume I was putting through it. The PO had changed out the radiator at ~175k (203k now) so it's relatively new. I still needed to know if it was plugged or clogged though so I reinstalled it, without the fans and ran the motor to temp. The AC condenser is in the way for me to get a good reading, so without the fans, I was able to use a infrared thermometer and sweep across the entire radiator from the back side with the fans gone. There was very little temperature deviation doing this from left to right and the infrared thermometer was reading with 5-10° of what the livedata/ecu was telling me--quasi verifying the temp sensor also but confirming the radiator is not plugged.

I genuinely don't think it's a head gasket. Even at it's hottest, when it should be pushing exhaust gases into the coolant system, it isn't. The car has never bubbled through the radiator or the overflow tank.
 

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Discussion Starter #9
how long were you running that odd ball ford motorcraft "thing" in there instead of a proper subaru thermostat?

same for the rad cap?

I hope those 2 things did not ruin a otherwise good engine.

_______

that ford dealer should have its licesene to do business revoked,

the big easy fix could be a JDM EZ30 250hp engine. (the one with the plastic intake, vs. the older 212 hp metal intake variety).
Did you reply to the correct thread? lol
 

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Did you reply to the correct thread? lol
I guess not,...need a nap. :| and should have clicked on your name to see if you had other posts you had about this problem.

there was a guy here with a 2005-2009 H6 here recently. .....ford dealer really likes cheapo parts.
 

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Ah yeah right, two radiators wouldn’t have identical symptoms anyway.

Could the gauge itself be inaccurate? Not the sensors. The actual thing you’re looking at.

1. Have you always gotten expected gas mileage and performance from this engine?

I’m now wondering what happened when the timing chain failed and the work was done. I can’t think of an actual likely way for that to happen - them pulling and damaging and reinstalling the pump (they wanted to replace it but owner didn’t?) or cavity or the jumped chain damaging the teeth on the water pump would all result in noise or other issues so it doesn’t seem plausible.

Have access to a scope and try to check out the water pump vanes or water pump driven teeth?

If the data given is accurate I don’t think it’s headgasket, but neither is it the water pump. A noncausitive Subaru water pump failure is an odd thing.

If you can - look up if this is possible, or pull the tstat and see if you can see the impeller vanes through the tstat opening. Take note if they look like OEM or if they look compromised in anyway. If you can see them turn the crank with a 22mm socket and give it a 360.
 

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If I had a nickle for every 150,000+ over heating running hot thread where tstat, cap and all other stuff is oem and fine where the old crusty radiator is argued to be fine? I would had a free dinner tonight. The outside of the radiator gets packed full of road debri bug carcasses etc and they become pretty useless at shedding heat. Replace the radiator and your good. Stop over heating it!! LOL
 

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The water pump vanes are the only.....albeit insanely improbable...possible failure mode of a Subaru water pump like this. Get a scope on those if possible. I think there is some access to them through the tstat and chain covers.
 

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send a coolant sample to Blackstone or Polaris? they might find combustuin products or some odd metals.

any loss of coolant in the radiator?

does the car coast normally? no dragging brakes or drivetrain issues? Tires all identical, no odd sounds? no odd jerking during parking maneuvers?

you try Water Wetter or similar coolant additive
 

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send a coolant sample to Blackstone or Polaris? they might find combustuin products or some odd metals.
I'd call them first and ask if this is worth doing, I'm not sure how long the exhaust gases remain in the coolant.

The chemical store tests can give false negatives for similar reasons - if exhaust gases are getting into the coolant yesterday or under certain loads - but not during the test, the car passes even though the headgaskets are indeed failing.

Are they not sensitive enough or the exhaust gases don't stay dissolved long enough, or a little of both....or?
 

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Discussion Starter #16
Ah yeah right, two radiators wouldn’t have identical symptoms anyway.

Could the gauge itself be inaccurate? Not the sensors. The actual thing you’re looking at.

1. Have you always gotten expected gas mileage and performance from this engine?

I’m now wondering what happened when the timing chain failed and the work was done. I can’t think of an actual likely way for that to happen - them pulling and damaging and reinstalling the pump (they wanted to replace it but owner didn’t?) or cavity or the jumped chain damaging the teeth on the water pump would all result in noise or other issues so it doesn’t seem plausible.

Have access to a scope and try to check out the water pump vanes or water pump driven teeth?

If the data given is accurate I don’t think it’s headgasket, but neither is it the water pump. A noncausitive Subaru water pump failure is an odd thing.

If you can - look up if this is possible, or pull the tstat and see if you can see the impeller vanes through the tstat opening. Take note if they look like OEM or if they look compromised in anyway. If you can see them turn the crank with a 22mm socket and give it a 360.
I've looked at the water pump impeller, several times, through the thermostat housing with an inspection mirror. It's a pretty tight area and getting a clear line of sight on it is double tough. All seems to be intact though with nothing obvious that stands out. It also passed my "wiggle" test that I gave it just to insure the impeller was in fact still attached to its shaft. All the blades of the impeller were there and in good shape with no obvious defects, pitting or wear that I could see. It also appears to be OEM and I believe it to be the unit that came with the engine from the factory.

Subaru offers no wear specification for the H6 water pump but does offer a wear specification for the 4 cylinder engines. As it turns out, .010" is enough wear to put the pump out of spec. I pulled the image below off the 2.5rs site because it was easily accessible. The more research I do about it, the more I see how critical the clearances are for a water pump. The problem is, I wouldn't be able to see ten thousandths wear on the pump. It'll have to come out to be inspected that closely.

Regarding the chain jumping time.. here's what the invoice states:
Customer states engine runs rough and check engine light is on. Check and advise. Tech found codes P0011--INTAKE CAMSHAFT POSITION TIMING - OVER ADVANCED (BANK 1) P0016--CAMSHAFT CORRELATION BANK 1. Tech confirmed rough running. Tech found Bank 1 Camshafts showing further advanced than on Bank 2 with scan tool. Suspect timing chain may have skipped. Recommend removing cover to inspect. Removed cover and confirmed Bank 1 cams are off by 1 tooth. Chain may have skipped on crankshaft gear. No reason seen why chain may have skipped. Recommend replacing both chains and tensioners. Customer questioned about removing heads due to prior overheating issues but decided to only replace chains at this time. Replaced 2 timing chains, 2 tensioners, crank seal and engine oil filter. Engine now starts and runs normally with no rough running or check engine lights on at this time.
Mileage in at that time was 194,436. Mileage when overheating issues began and radiator was replaced: 178,212.

It's unclear to me who asked about removing the heads to do the head gaskets--whether it was the PO or the shop. There's no mention of the water pump being discussed or removed. It's a no brainer to me to replace the water pump while you're there but I suppose that shop was looking for job security :rolleyes:

Further, and I'm speculating here, but, the water pump appears to be driven by bank 2 timing chain so the failure of bank 1 timing chain/tensioner would not have impacted the sprocket driving the water pump.

Regarding the gauge accuracy--up to 210° the gauge stays about dead center. Beyond 210° the gauge sweeps up. At 230° the gauge is at the 3/4, or upper most mark before getting into the red zone. Below ~190° the gauge is below center. I believe the gauge to be accurate and functions in accordance with ECU ECT as provided by scan tool live data.

Also, performance from the car is great. There's plenty of pep in it's step. Fuel economy is in line with the other Subaru's we have currently and have had in the past slightly exceeding the 03 H6 LLBean we just sold and being comparable to my 2.5GT if I could keep my foot out of it lol.

Thanks for time and effort--truly.
 

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Discussion Starter #17
If I had a nickle for every 150,000+ over heating running hot thread where tstat, cap and all other stuff is oem and fine where the old crusty radiator is argued to be fine? I would had a free dinner tonight. The outside of the radiator gets packed full of road debri bug carcasses etc and they become pretty useless at shedding heat. Replace the radiator and your good. Stop over heating it!! LOL
The radiator has been removed from the vehicle and externally inspected. I can assure you air flow through the radiator is absolutely unimpeded. I can also tell you airflow through the AC condenser is unimpeded as well. No bugs, no debris, no leaves, etc. The fans have no problem pulling air through them either. All shrouds are intact and functional as well.

Also, I reinstalled the radiator without the fans and brought the engine up to temp. I used an infrared thermometer to sweep across the back side of the radiator looking for hot or cold spots. There was little variation in temperature across left to right, or up and down the radiator. Reading ECT from the scan tool live data feature, the infrared showed temperatures within a few degrees of what the ECU was reporting. Any internal clog in the radiator, I imagine, would have shown up as a cold spot, of which there were none.

If air couldn't flow through the radiator, it would overheat and I get that. This is why I pulled the radiator out to visually inspect it. As well, if coolant can't flow through the radiator (due to clogs internally,) the engine would overheat and this is why I thermally inspected it looking for temp variations of which there were none. Air can move freely through the radiator. It appears coolant can move freely through the radiator. Beyond those two, one can only question whether coolant is flowing through the system at an appropriate rate which appears to me to point to the water pump. It's the last part of the equation--the only part that hasn't been tested or is untestable.
 

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that's good it has OEM pump and they don't look like they sat in saltwater or something...but still a head scratcher. you quite literally can't find a water pump failure - it would be good to hear from someone seeing H6's on a weekly/monthly basis and see if they've ever actually seen a non-leaking, failed H6 water pump. i wouldn't believe it unless someone really well versed in Subaru's told me.

Further, and I'm speculating here, but, the water pump appears to be driven by bank 2 timing chain so the failure of bank 1 timing chain/tensioner would not have impacted the sprocket driving the water pump.
I doubted we'd find anything, thanks for posting the diagnosis report, they're interesting to look at but not telling here. The only thing the two chains share is the probable poor oil choices leading to the compromised tensioner which likely caused the jumped timing.

Regarding the gauge accuracy--up to 210° the gauge stays about dead center. Beyond 210° the gauge sweeps up. At 230° the gauge is at the 3/4, or upper most mark before getting into the red zone. Below ~190° the gauge is below center. I believe the gauge to be accurate and functions in accordance with ECU ECT as provided by scan tool live data.
Good, your other posts indirectly were showing that, but wanted to clarify.

Subaru offers no wear specification for the
That is odd since they likely have design data suggesting something and usually specify limits, but practically those never fail that way and literally no one in the country is checking it.

There's no mention of the water pump being discussed or removed. It's a no brainer to me to replace the water pump while you're there but I suppose that shop was looking for job security :rolleyes:
They do occasionally leak out the weep hole and for that reason I replace them due to how labor intensive the timing chain cover is - but I can somewhat understand that not all shops will routinely replace them since failure rates are so low and local, economic, and other realities exist, though they should let the customer choose and not just ignore it.
 

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I'd call them first and ask if this is worth doing, I'm not sure how long the exhaust gases remain in the coolant.

The chemical store tests can give false negatives for similar reasons - if exhaust gases are getting into the coolant yesterday or under certain loads - but not during the test, the car passes even though the headgaskets are indeed failing.

Are they not sensitive enough or the exhaust gases don't stay dissolved long enough, or a little of both....or?
I've seen the service listed at Polaris but, def. worth a call to confirm they can spot combustion chamber byproducts.

worth it? - I say it is when you compare it to changing what seems to be a perfectly fine water pump.
 
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