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Hey all,

 

I have a 2009 Subaru Forester XT with a 5 speed manual.

 

I have noticed my cars overflow bottle is always requiring a topup, this cannot be normal.

 

So I have been looking everywhere for a leak. I have used my coolant pressure tester and had the system at 20psi and have not been able to find a leak :(

 

It will slowly loose psi, approx 1 psi every 3-5 minutes. Sometimes it will drop quite quickly...

 

I have checked the top two radiator hoses, they appear fine. no leaks there radiator side and engine size. Heater hoses look good no weeping there, Thermostat housing - no leaks.

 

I am starting to run out of places to look.....I can smell coolant most times when I pop the bonnet - the car runs great, no issues with power and the oil/coolant are not contaminated.

 

Turbo lines look ok as well - no crusty coolant residue and no leaks while under pressure.

 

 

I got a buddy to follow me while I gave my car some heavy loads/acceleration to see if there was any smoke out the tail pipe - apparently no smoke.

 

I am lost!

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Headgasket?

 

Can turbos leak internally and consume coolant, I don’t do turbos so I don’t know.

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Head gasket.   Turbo would blow a cloud of white if it was leaking.  Bright light , inspect the bottom side of the heads where they meet the block, chances are you will spot a very small drip.  If you don't see one look on your exhaust system for stains. That engine if the head gaskets leak it will be external.They drip on the exhaust burn off and leave the slight smell of anti freeze.

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I agree with the above posters. Need to check the HG for coolant leaks.

Though uncommon on the turbo cars, it is possible.

 

There is also two coolant lines going to and from the turbo that can leak.

 

And if you did your pressure check with the coolant hot/warm/anything above ambient temperature. When you put 20 psi in the system and let it sit. As the coolant cools off. It will naturally drop in psi as the coolant is expanded (when warm) and as it cools it "shrinks".

Edited by golucky66

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My 2010 non turbo Forester has been loosing coolant from the day one I bought it new.  The dealer, when the car was under warranty, did not find anything.  I pressurized it and did not find anything.

 

I keep adding coolant and... wait.

 

And yes, the smell is there also.

 

Sam

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My 2010 non turbo Forester has been loosing coolant from the day one I bought it new.  The dealer, when the car was under warranty, did not find anything.  I pressurized it and did not find anything.

 

I keep adding coolant and... wait.

 

And yes, the smell is there also.

 

Sam

did the dealer tell you "it's all in your head"?

heh heh

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I have got the car in the air, have it under some decent pressure in the cooling system 20-22psi. Don't really want to run much more into it.

 

Have checked where the heads and block meet (headgasket), while there are some dried coolant stains in that area, I could not see any leaks.

 

These stains could have been caused by spilt coolant I am guessing.

 

I did have a look at the water pump as best as I could without taking off the harmonic balancer etc, there is also some dried coolant around the water pump - but my inspection camera is not that great quaility so its hard to see if thats 100% the area.

 

 

I have only done my pressure testing on a cold engine. Will leave it pressurized for a bit and hopefully find a leak/drip somewhere...

 

I can definitley smell coolant from the engine bay, just want to see a conclusive sign to say its "XX" before pulling the motor and taking action.

 

Worst case I think I will just keep topping it up - I am sure it will get worse and the problem will reveal itself.

Edited by booki

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Turbo models don't exhibit the HG problems of external weepage. 

 

If you can smell it, then it's a leak that can be fixed. Run the pressure up to 25 or 30 psi. You'll find the weakest link. What aree you afraid of? If anything fails at less than 2x nominal system pressure it should be replaced anyway. 

 

GD

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I thought I would damage something at that kind of pressure. I thought I was being pretty bad rump roast with 20-21psi haha.

 

Anyway after leaving it pressurized I managed to find two very miniscule leaks.

 

One where the expansion tank connects to the radiator, and one on the bottom radiator hose going to the motor. All these clamps are the factory clamps - the rabbit ears style I call them. Swapped them out for regular old worm gear style clamps.

 

Here is hoping I won't have to keep topping up - otherwise bring on 30psi haha.

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You might have a pinhole leak in a hose. These are harder to find as they typically won't leak until a certain temp/pressure where it'll open, spray a fine mist or stream akin to a small squirt gun, then close after the engine is off, sealing the pinhole back up. When driving and after engine is at full temp, if you see "steam" rolling up from under the hood, pop it open and see if it's visible (leave it running). Virtually any hose holding coolant can do this, and it can spray anywhere, whether that's back onto the engine, trans area, firewall, or even directly on the ground.

 

Plastic radiators can crack over time. Or say you replace upper/lower hoses and over tighten, it can crack the tube on the hosing, or crack and leak under the hose end.

 

Semi-loose hoses, whether to/from radiator, to/from heater core, etc. can leak at the hose ends, or hose itself.

 

Heater cores themselves can leak into the actual car (speaking in general terms here) and they'll often leak behind the carpeting which gets soaked up by the padding. You'll most likely smell that though at some point inside the car, and IIRC, the windows will fog up constantly. Been ages since I ran into that. IF the heater core is leaking and it's bad, on some cars you can carefully pinch the feed line to the core with vice grips, then zip tie the handle up as a limp-home or get to work temp fix, or time permitting, loop a "U" section to the in/out on the engine if you can live w/o heat for a day.

 

Turbos as others mentioned, will typically PUKE smoke bad enough that a cop will most likely being pulling you over for it as it'll linger in the air. Turbos that far gone most likely won't boost, or it'll "howl" as it spools up, which can be from so much play the fins clip themselves off against the housing.

Edited by Bushwick

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The turbo itself is basically incapable of burning coolant. The cooling passages are cast into the iron CHRA housing and are not open to any of the shaft bushings, or mechanical seals. The huge plumes of smoke you see from turbo failures are straight unburned oil dumping into the turbine housing and being sucked into the compressor housing and into the cylinders. 

 

GD

Edited by GeneralDisorder

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Checked the coolant level in the overflow before driving today - had to top up quite a bit. hoping that just a some air was in there after removing a hose to fit a worm gear clamp on.

 

Fingers crossed for tomorrow, otherwise I will be pressure testing again at a higher psi.

 

I am a little worried if the heatercore will hold up or not to that kind of pressure though.

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Booki; The overflow tank is not the place to check coolant level...   You must look in the radiator .

 

On a turbo you have to do it at the upper water tank.

 

GD

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I have a aftermarket alloy style radiator. Recently replaced due to a split in the header tank on the factory plastic one. Car was loosing/using coolant before the rad split open though.

 

I am assuming that the overflow should stay pretty much at the same level though? It keeps going lower after I top it off - thats why I assume im loosing coolant.

 

The expansion tank (upper water tank) is always at the correct level, but I am assuming thats because I keep topping up the overflow.

 

If I let it run low in the overflow, I assume its only a matter of time till it starts loosing it from the expansion tank.

Edited by booki

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Its not an expansion tank. It's the upper reservoir. It keeps the level of coolant higher than the turbocharger. The overflow bottle IS the expansion tank. Same thing. 

 

Its going somewhere. If you smell it its on the outside of the engine. Put the pressure to it. 

 

GD

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Do you have any silicone hoses on your forester?  I ask because silicone has x10-x15 the permeability of EPDM rubber and can allow for coolant loss through evaporation.

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maybe UV dye would help?

 

I once read of a throttle body with some odd crack that allowed coolant to be sucked into the engine!

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Do you have any silicone hoses on your forester?  I ask because silicone has x10-x15 the permeability of EPDM rubber and can allow for coolant loss through evaporation.

 

No silicone hoses on my foz - I have heard the same thing that silicone hoses will allow evaperation at a way higher rate then rubber hoses. Even so, in the event I did have silicone hoses, I doubt I should need to top up the overflow after every engine heat cycle.

 

 

maybe UV dye would help?

 

I once read of a throttle body with some odd crack that allowed coolant to be sucked into the engine!

 

 

That sounds like a good idea!! Are there special dyes for cooling systems or just any old dye will do? Can it damage anything by putting it in there? Logic makes me think not, but never hurts to ask.

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i think they haveproper stuff at the parts store - maybe a rental of a light and goggles too.

 

I have only used premixed r134a with dye - found a bad a/c hose.

Edited by 1 Lucky Texan

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Put 25psi into it quickly today - didn't really want to go much more.

 

Couldn't see any leaks but didn't have it in the garage to check it out properly (was just outside in the sun).

 

At 25psi I would think the leak would be super obvious....but apparently not !

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Any Subaru with headgasket issues could  / may  consume water  internally  through combustion chambers out the exhaust  if there is no evidence of external coolant loss otherwise  - when engine / exhaust up to running temperature examine exhaust emissions.

Had an EA82 that did this.

 

If you saw evidence of coolant colouring / staining  on the underside of something  then there is a probably / coolant leak  from  somewhere above

Edited by subnz

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The overflow tank will go up/down on it's own. Is it possible the radiator was just low to begin with?

 

 

Also, unsure of probability here, but I know my 95's overflow tank just has a rubber hose dropping through a hole in the top, which is kinda loose, and allows the coolant "smell" to seep out if hood is up and engine has been running (can't smell it with hood down like an actual leak or some cars you can smell coolant from 10' away).

 

 

It *might* be possible you are actually smelling the overflow tank and the radiator was low to begin with, and has been pulling coolant from the overflow tank to compensate.

Edited by Bushwick

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Alright. Pretty sure I have diagnosed the issue - to those following my diagnosis will be "uploaded" shortly...

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