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Discussion Starter · #1 ·
Another question with my 2003 Outback. I'm up to 120,000 miles.

A few months back I replaced a leaking radiator hose. I replaced the thermostat while I was under there, then re-filled the coolant, and I thought I had burped the system adequately.

Fast forward about two months. I took it in to replace a blown wheel bearing. My mechanic noticed I was running really low on coolant. He had to put in about 1.5 gallons, IIRC.

Fast forward to last night. I noticed the heat was less than I would expect it to be while driving. So this morning I pulled the cap and I was low. It took maybe as much as 3 quarts, definitely more than two just to replenish the radiator.

I have not seen any antifreeze on the ground. There is no sign of leakage on the radiator hoses. I park it in a garage with an epoxy finish floor, so I'll notice everything it drips when I leave and when I get home. I'm leaking some oil from a leaky head gasket and valve cover gasket.

There is no sign of leakage near the radiator cap either.

Any idea where I would be losing coolant? This is a head scratcher. Could this be related to the leaky head gasket? Sorry if that's a dumb question; I'm not that educated on auto issues.
 

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03 H6 OBW & 06 WRX Sportwagon
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did you use an OEM-style thermostat? (it matters)

either being pushed out the overflow tank (bad HG), 'burned' (blown out the exhaust through a bad HG), it's in the oil (bad HG) or it's in the automatic transmission if so equipped (through leaky cooling coil?) or you're missing where it's being leaked/sprayed out.

what about the overflow bottle? does it stay low or fill up? did you change the radiator cap? Did the mechanic have any suggestions?
 

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What he said ^ OEM only thermostat the cheap parts store thermostats damage more Subarus than any other cheap ass parts store parts.

Make sure the over flow hose is not split or the cap or nipple at the radiator where the over flow hose is attached is leaking etc. Double check your hose you installed make sure it is seated good. Did you pop the radiator cap off and top off while the car was idling?

Top it up and check your mileage and keep a close eye on it to get a sense of just how much your loosing. A bad seal on the Tstat - leaky water pump - leaky hose etc can all be easy possible fixes. HG would be a possibility but make sure the rest of the cheap stuff is all fine first.
 

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Discussion Starter · #4 ·
I bought the replacement thermo at the Subaru dealership per recommendations I saw here.

I haven't given the overflow hose a real close look. I'll check there.

I didn't change the cap. I bought an OEM one, but the original looked to be in good condition on visual inspection.

This morning I didn't top it off while idling, so I could still have some air backed up in there. My mechanic fully burped it while he had it about a month ago.
 

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I bought the replacement thermo at the Subaru dealership per recommendations I saw here.

I haven't given the overflow hose a real close look. I'll check there.

I didn't change the cap. I bought an OEM one, but the original looked to be in good condition on visual inspection.

This morning I didn't top it off while idling, so I could still have some air backed up in there. My mechanic fully burped it while he had it about a month ago.
How many miles in that month? That should be a good indicator of any leak pending whats in there now. Take a peak under the cap - check the over flow bottle level and report back.

Side note some of the over flow hoses were clipped long with a flat cut and had a tendency to suck to the bottom of the over flow can. Easy fix is to just clip the bottom end of it at a 45 degree angle to keep the hose from sucking to the bottom of the bottle. This might be the issue or part of the issue also.
 

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How many miles in that month? That should be a good indicator of any leak pending whats in there now. Take a peak under the cap - check the over flow bottle level and report back.

Side note some of the over flow hoses were clipped long with a flat cut and had a tendency to suck to the bottom of the over flow can. Easy fix is to just clip the bottom end of it at a 45 degree angle to keep the hose from sucking to the bottom of the bottle. This might be the issue or part of the issue also.
good point, after I read that here, I made the angle cuts on both my car's.
 

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Car: 2008 Tribeca, 2010 LGT, Sold: 2005 XT Limited
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There are several places where the leaking coolant goes right on to the exhaust and evaporates, especially around the water pump. Did you put in a new gasket when you changed the thermostat? Although I suspect that hose is torn (it can be very challenging to get off and the 'vigorous' effort can easily put a small hole in the hose) or the hose clamp is weak. This is right above the exhaust on my 05. But you might notice some white smoke if you open the hood after getting to temperature.

head gasket also needs to be considered.

Tom
 

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Discussion Starter · #8 ·
How many miles in that month? That should be a good indicator of any leak pending whats in there now. Take a peak under the cap - check the over flow bottle level and report back.

Side note some of the over flow hoses were clipped long with a flat cut and had a tendency to suck to the bottom of the over flow can. Easy fix is to just clip the bottom end of it at a 45 degree angle to keep the hose from sucking to the bottom of the bottle. This might be the issue or part of the issue also.
I drove likely under 1000 miles in that month. I've checked the overflow hose, and there is no evidence of leakage. It's also cut at a 45 on the bottom.
 

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Discussion Starter · #9 ·
There are several places where the leaking coolant goes right on to the exhaust and evaporates, especially around the water pump. Did you put in a new gasket when you changed the thermostat? Although I suspect that hose is torn (it can be very challenging to get off and the 'vigorous' effort can easily put a small hole in the hose) or the hose clamp is weak. This is right above the exhaust on my 05. But you might notice some white smoke if you open the hood after getting to temperature.

head gasket also needs to be considered.

Tom
That was actually what precipitated replacing the thermostat. My old hose had gone bad and was leaking onto the exhaust. I'd smell it burning, which would usually smell kind of like maple syrup in the cab of my car. I replaced it with a new hose and new hose clamps. I've checked there, and there is no sign of leakage from the new hoses.

I didn't see that there was a gasket to the thermostat. Am I missing something?

I do have an oil leak as a consequence of a head gasket leak. I keep a close eye on my oil, and haven't seen any evidence of coolant in my oil.

Like I said, this one is a real head scratcher. It's possible that it still hasn't been re-filled completely since I changed the hoses, but I doubt that. I think there's been about 5 gallons go in since then. I forget the exact capacity, but I believe it's around 3 gallons (2.5L engine).
 

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HG leak could be both oil and coolant externally not internally. The classic 99-2002 ish HG leak was commonly spotted driver side head - coolant would run back to the back bottom corner which is right over the exhaust down pipe. So the evidence would evaporate pretty quick after shut down but like you pointed out you could smell it if you started to pay attention and sniffing around a little. Could be part of whats going on with your car.
 

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I didn't see that there was a gasket to the thermostat. Am I missing something?
There is an 'o-ring' like seal on the thermostat/housing. like this:


Tom
 
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