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Subaru overheating, a new theory;
My Father has a 1999 Subaru Outback 2.5 automatic wagon with 246k.
I replaced his head gaskets, water pump, timing belt and front seals about three years ago. Friday night on a mountainous road it overheated. That night I replaced the thermostat with a new stock Subaru one, and it overheated about a mile later. After getting it towed to my garage I was able to look at it today. Changed the upper rad hose. Flushed and replaced the cooked coolant with strait water, checked the cam timing. It was correct. The fans work properly. Reassembled the car and took it out for a test on "Head gasket Hill." About 72° ambiant, AC on the coldest setting, ran up the seven mile long, seven° incline. The AC remained ice cold, and the gauge stayed at below the normal position. Untill two miles past the top of the mountain. Now the gauge spikes, and water is boiling into the overflow. I check the upper hose, VERY HOT, check the lower hose, 100°f or less. Aparently improper coolant flow! Top hose hot, bottom hose cold, bad flow. I THINK that I will find out tomorrow why. I THINK that because he has a slight power steering reservoir leak that the ATF has saturated the timing belt, and under load causes the water pump to slip, causing overheating only under substantial load. Hopefully, more on this tomorrow!
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www.svxfiles.com The first SuperCharged SVX, the first 4.44 gears, the first equal length headers, the first phenolic spacers, the first Class Glass fiberglass hood, the first with 4, 4.44s in his driveway Fiberglass Hood thread My locker 4.44 Swap link |
#2
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Re: Subaru overheating, a new theory;
Interesting theory. I also wonder if the whole headgasket/overheating thing isn't a chicken and egg scenario as well. Does a car overheat because of a bad gasket or does the gasket leak because of stresses caused by an overheating event?
I went to the US Army Military Academy in West Point on Friday and Saturday for a basketball coaching clinic. I didn't realize how high of a hill/mountain/cliff it sat on. It was such a steep climb and such a long climb that I grabbed my OBD2 reader to check the engine temperature as I was curious. I was happy to see it only reached 203F at the top of the hill. What was maybe more amazing is that is hit 183F by the time I hit the bottom of the hill/mountain. I guess that shouldn't have been too much of a surprise as normal is around 193F when I am cruising down the highway. I have just never seen the temperature get that low once the car warms up. I guess coasting down a long hill will do that. The temp gauge never moved out of its dead zone the whole time. 14 months after the TEMP SENDER saga and all is still well........... On the way home I checked the "highway" gas mileage and it came in at 29.25MPG. I thought that was pretty good considering that RT86/RT17 in NY is a pretty hilly highway. My TC unlocked a few times on the drive as some of those hills can be long and steep. Plus there were lots of annoying construction zones.
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Tony 1996 Polo Green Subaru SVX LSi, 168,XXX miles, Redline D4 ATF, Redline 75W90 gear oil, K&N HP-4001 Oil Filter, Mobil 1 5W50 FS (3qt) and 5W30 High Mileage (4qt) Oil Blend, Motul RBF600 Brake Fluid, AC Delco A975C Air Filter, NGK BKR6EIX-11 plugs, Centric Rotors, Power Stop Evolution Carbon Fiber Ceramic Brake Pads 2005 Gray Acura RL, 165,XXX miles, Redline D4 ATF with Lubegard Platinum Protectant, Mobil 1 5W20 High Mileage Extended Performance Oil 2009 Red Toyota Venza, 123,XXX, Mobil 1 5W30 High Mileage Oil 1992 Red Ferrari 348 ts, 82,XXX, Redline everything Last edited by Huskymaniac; 09-27-2011 at 05:58 AM. |
#3
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Re: Subaru overheating, a new theory;
How high is WEST Point??/ Last time I was there we watched eagles soaring BELOW us . That is a good test of a car for sure. I bet altitude may have played a part also.
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#4
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Re: Subaru overheating, a new theory;
Maybe a severely restricted radiator (not enough flow)? Did you check while flushing the system?
Tapani |
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Re: Subaru overheating, a new theory;
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Keith Last edited by kwren; 09-27-2011 at 12:47 PM. |
#6
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Re: Subaru overheating, a new theory;
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It is a single row, just like the stock Outback radiator, that year.
__________________
www.svxfiles.com The first SuperCharged SVX, the first 4.44 gears, the first equal length headers, the first phenolic spacers, the first Class Glass fiberglass hood, the first with 4, 4.44s in his driveway Fiberglass Hood thread My locker 4.44 Swap link |
#7
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Re: Subaru overheating, a new theory;
Quote:
Keith |
#8
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Re: Subaru overheating, a new theory;
i have seen this happen twice, on the same car. car came in for similar reasons and after taking off the timing cover i could spin the water pump by hand with the belt still on. told customer it needed new belt and ps pump. customer declined ps pump but replaced belt. returned several months later for new belt and ps pump for the exact same problem. the difficult thing was finding new timing cover gaskets (for a cheap customer that wouldn't replace the cover with a new gasket) because they had swollen so bad they wouldn't fit back into place.
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#9
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Re: Subaru overheating, a new theory;
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Mitch Hansen
"uncamitzi" This is a Dark Ride 92 Teal SVX LS-L 128K tranny swap with 4.11's Well.. my days of not taking you seriously have certainly come to a middle . |
#10
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Re: Subaru overheating, a new theory;
Ah, the EJ25 is such a GREAT engine...
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#11
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Re: Subaru overheating, a new theory;
OK, time to eat crow.
New timing belt, new water pump, still overheats. I now realize that it has a leaking head gasket, or cracked head ... Moreonthis later...
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www.svxfiles.com The first SuperCharged SVX, the first 4.44 gears, the first equal length headers, the first phenolic spacers, the first Class Glass fiberglass hood, the first with 4, 4.44s in his driveway Fiberglass Hood thread My locker 4.44 Swap link |
#12
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Re: Subaru overheating, a new theory;
The key...
Quote:
Keith |
#13
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Re: Subaru overheating, a new theory;
did you bleed the cooling system after re filling it and replacing the t-stat?
I had a similar issue coolant was full, fans worked but still got random overheating, come to find out it was air bubbles hanging out over top of the t-stat, then when the coolant warmed up, the t-stat stayed cold because it had the air bubbles keeping the t-stat from opening. the air bubbles kept the hot coolant from warming the t-stat enough to open and allow circulation. Not even sure if it's still necessary to do that, just a thought.
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2003 Baja Sport 1994 SVX LS 1992 SVX LSi parted out |
#14
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Re: Subaru overheating, a new theory;
To eliminate that problem, I simply fill the radiator, then disconnect the end of the big hose at the top of the radiator, move the end over far enough to poor collant down the hose and the air trapped on the other side of the thermostat come right out. It made sense to me, so I tried it one day! Works every time for me... so far
Of course, I always fasten the end of the big hose snugly back to the top of the radiator Keith |
#15
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Re: Subaru overheating, a new theory;
another good trick is to jack the front of the car up as high as you can. this puts the radiator cap high in comparison with the rest of the cooling system and tilts the surfaces a little so air has a harder time trying to find a place to hide.
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