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Discussion Starter · #1 ·
HI all,
Have been maintaining my LLBEAN awesome 2004 outback in "uber" style and am up to 135k mileage. I live in So.Cal and take a lot of trips to Big Bear. This means driving about 60-70 miles in temps of about 90-105 degrees, followed by an uphill grade on hwy 38 that is relentless. My temperature guage normally sits at about 90-95 degrees (9:15 on a clock), but on the incline to Big Bear it rises another 10-15 degrees or so (@9:45 ish on a clock) and I get pretty nervous.

It only happens in hot weather and once I get up to where the temperature drops down to about 80 degrees outside, the guage goes back to normal. There are about 15-20 minutes of stress seeing my guage go up and I freak out.

Last summer, I had the car checked out and ended up replacing the thermostat and the radiator as radiator was leaking a little bit on bottom.

On recent trip up hill, preceded by 95 degree temps for an hour prior to the big incline, I tried running the heater and the guage went up, but not quite as much.

I am going up again in a few days and the outside temp will be about 100 plus degrees for the hour preceding the incline and I am nervous. I go in for oil changes and all the services so often that I am pretty sure the hoses are okay. Am I just being overly nervous or does anyone have ideas as to whether more stuff could be wrong? I'm just afraid to go up the hill in the heat.

THX
 

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(formerly) 03 H6 OBW , (presently) 06 WRX Sportwagon & 2021 Honda CR-V
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I had s similar scare in Nevada one summer. Our 03's gauge would creep up on the uphill grades. Of course it was 114*F, the car had some gear loaded in it, 3 adults and a/c running - plus I was doing maybe 10 over the speed limit.

I think under extreme conditions, this model H6 has marginal cooling capacity. I've read others complain of the same type situation.

Nothing wrong with triple checking all the components, using a car wash nozzle to clean the dead bugs out of the radiator, maybe taking the hills a little slower. making CERTAIN only OEM (from a dealer) style, large 170* thermostat has been installed and is opening as it should. But I'm not sure much else can be done. perhaps a slightly different anti-freeze/water ratio or using some special 'water-wetter' fluid - dunno.
 

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Out of curiousity, see if your reservoir is getting dirty. It might be an indication that you are getting a tiny head gasket leak putting bubbles into the system.
 

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The temperature in my 2004 Bean will climb on steep hills when the temperature is high (90+). The hill has to go on for a while for it to start climbing, and I've had it get as high as the top line of the normal zone. It has never overheated (gone past that line). I've seen this happen 3-4 times this summer, always on hot days and on very steep prolonged inclines with the A/C on. I'm talking 15-18+% grades here, but I'm sure if the temperature was over 100 (which never happens here) it'd do it on less steep hills.

Unfortunately, I think it's just a limitation of the cooling capacity in these H6s.
 

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Discussion Starter · #5 ·
thanks everyone for your support and ideas!!! I guess I can call my mechanic and find out what kind of thermostat they put in. I will try the car wash nozzle on the radiator.

Gregg--which reservoir are you referring to?

Thank you so much everyone!!!
 

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The radiator overflow bottle or reservior as it may be referred to. After doing a lot of research, I have been reading, hearing and experienced some of the H6 motors developing some very small head gasket leaks when under load and warm around the 135k mark give or take some. When doing a radiator pressure check it will often show nothing. A leak down test might show a slight variance but the engine basically needs to be removed to hook up the tester.
One test which should remove all doubt, which is kind of a strange way to do it this.
1. Make sure the radiator is cold and completely full.
2. Get a long clear flexible plastic hose about 7 feet long or so.
3. Get a clear plastic container about a 1 quart to a 1/2 gallon.
Now, take of the over flow hose that goes to your overflow reservior and put on the clear plastic hose. Run that hose under the hood into the the car where you sit. Put some water in the clear plastic bottle and put the hose into it. Now...go out for a drive. Go up some steep grades and work the motor. You will antifreeze being pushed into that clear bottle in the car. However, soon all the air in the hose should be pushed into the bottle and out and there should be no more air. However, if air keeps coming and coming and coming, you have a head gasket leak.

I did this test on my car and it is basically fool proof. I was on a long vacation and the car went fine for about 1000 miles. After that, it started to get hot for no apparent reason. I noticed my reservior was kind of dirty. The smudgy feel from past experience was usually an exhaust leak into the coolant. I drove the car another 2000 miles to finish off our trip and the bubbles get coming and coming the whole trip and the antifreeze has that dirty look to it. When I got home, I did a pressure check and it proved inconclusive. A hydrocarbon test would probably show positive but I know I don't need to go the extra step here.
 

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Hi all,

Next time you are going uphill, with a load or not, however you have the car loaded when it does it, downshift to 3 while on the grade. The programming changes with the gear change and the higher rpm and torque will lower the calculated load and mapping. In other words, the car will not run up the hill in 3rd, if it downshifts from D due to tps position, as if you are passing, but level out. If it still overheats, the system has an air gap, low coolant or sticking/incorrect thermostat.

100 plus days in Texas, a drive from Austin to Corpus Christi will allow the temp to rise when cruising 80 or more. I just slow down to 70 until it levels out again, then speed back up and reset the cruise. I have been considering a larger core radiator.
 

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(formerly) 03 H6 OBW , (presently) 06 WRX Sportwagon & 2021 Honda CR-V
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I think that's a good point about downshifting - wish I had thought to try that.

Had a Toyota once that I would DS on a certain hill due to lugging. Guess I never associated that with highway speeds and fairly gentle slopes.
 

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depends on programming - you can override that with the gear selector.

the manufacturers try to eek-out as a high a mileage figure as possible , so the systems are programmed to stay in the highest gear in which the car will run smoothly.

Downshifting under the circumstances discussed here might help for 2 reasons, coolant circulation might be faster, and the combustion charge lingers in the cylinder for less time.
 

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Discussion Starter · #12 ·
Made it through the Murrietta/Temecula/ drive a few weeks ago in 111 degree heat on hwy 215 going from San Diego to Palm Springs. This road seems to be a slight incline up for a full 60-70 miles. Thermostat went to 3/4 mark again, turned off a/c, blasted heater, opened windows, and thermostat went back down. I hadn't read these posts about trying the downshifting, so I will try that next. I did also make it up the hill to Big Bear but left super early in the morning so temps were only in 80's and guage managed to stay in a reasonable zone with only a little bit of upward movement.
It just seems that after replacing thermostat & radiator that this should not be an issue! Since the new Subies are up in high 20k/to low 30's, it seems to be worth it to ride this out or have dealer do a diagnostic.
However, first dealer told me if it wasn't something simple like a rad. flush, that it could be something like head gasket seal fix and starting repair cost of $1800 +.

How do you know when you spend #$ to fix if that will be it for a while or if it's time to get a new one. Not easy!!!
 

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(formerly) 03 H6 OBW , (presently) 06 WRX Sportwagon & 2021 Honda CR-V
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unless you have other symptoms like bubbles in the coolant, it isn't head gaskets.

but let's suppose it was. Assuming the rest of the car meets your present and near future needs and has been well maintained (that is, you'd like to keep driving it) - $1800 is what? 5 payments on a new car?


But it really is just a 'quirk' that this gen has. I've read of 3-4 other reports - not just you and me.
 

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cardoc , would an oil cooler with it's additional radiator be enough to help?


 

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If the car is operating in it's intended temperature range, I see no reason to throw money at the car adding additional coolers. I know we're all nitpicky about our cars, but I say just let the car do it's thing - if it's not overheating then it's fine!
 

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I think there is some concern for those folks that are operating at the edge of the envelope here - extremely high ambient temps, plus towing or other loads, plus hill climbing at highway speeds. If you do this regularly, I think some special attention to equipping the car to maintain 'normal' temps is justified. It will only get worse as components age and eventually the weakest link will fail. If you're lucky, it will only be a hose - if not, could be a blown headgasket and a warped head. If you only drive under those conditions at rare intervals (like me) at least folks have been advised and can triple check cooling systems before their trip, be more observant of the temp gauge on the trip and try slowing down or downshifting if temps creep up.
 

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cardoc , would an oil cooler with it's additional radiator be enough to help?


Transmission and oil coolers are always a good idea, especially when towing or heavy loading. I have only had temperature rise when a thermostat isn't opening all the way, a fan is not kicking into hi, its low on coolant or the ja***sses in front of me won't move over on 100+ days.

Forget the head gasket. If you are not losing coolant, its a flow issue, which follows the fact that you turned on the heater to help cool it. Put a Subaru thermostat in, make sure you run it with the cap off for a couple thermostat cycles when you fill it back up to insure you get all the air "burped" out.
 

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If the car is operating in it's intended temperature range, I see no reason to throw money at the car adding additional coolers. I know we're all nitpicky about our cars, but I say just let the car do it's thing - if it's not overheating then it's fine!
Subaru thermostats start to open at 176 and are full open at 196. The temperature gauge should be at the mid range when operating. When it creeps up above that point, its approaching 225 or higher and the temperature can climb quickly. It is a concern and indicator of a problem.
 

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True - the general consensus seems to be that a little gauge creeping is normal though. Granted, I've never had the pleasure of driving an H6, only a handful of H4s, so I don't have any first hand experience with them. It does seem to be a big motor for the thin little radiators our Subarus get though :)
 
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