Coolant disappearing from Legacy LX '94

About 7000KM ago I bought my first car - a Legacy LX '94. The first thing I did was replacing the oil, oil filter, checking fluid levels etc. Every was fine then. Yesterday, however, I did a quick check before making a 500km trip. I first drove to town (5 mins) and then checked the fluids. When I opened the hood the first thing I noticed were two places where steam was coming from the radiator (most left and right to the middle), it was only a little little bit though (like the steam coming from coffee). The first thing I obviously checked was the coolant. The reservoir was all empty and it drank about 1.25L of coolant to come up to the low level again - it kind of surprised me, it was at full 7000KM ago.

 

I think I've been driving with this low level of coolant for a while because I noticed that the 'characteristic bubbling' I always hear when accelerating was gone for a couple of weeks already and this sound was back when I topped up the coolant. The temperature indicator of the engine however, never reached half way the indicator bar so I don't think the engine has been overheated.

With the bubbling stopping something else began (it's only now that I think of this) namely a much higher RPM during the first minutes of driving. It usually made about 1000RPM when the engine was warming up but lately it was more like 2000 - 2200RPM. I was only last time when it started worrying me - I could drive 50km/h without throttle... It seems that with the bubbling coming back the really high RPM is gone.

 

Should I be worried about some kind of very small leak? I've checked it and there are no traces of coolant anywhere on the engine. Because it's a new car (well for me at least) I used to park it on a piece of cardboard so see if anything leaks - however, the cardboard doesn't show any traces of leaking.

 

Thanks a lot for all your help!

 

P.S. I've just bought a Haynes repair manual so you don't have to make complicated explanations where I can find some part - I can look it all up now

"Characteristic Bubbling" does make you wonder about the HG's. That's not normal!

 

As for the coolant disappearing, your radiator shouldn't be steaming. If you see steam, then you have spotted your leak. If the leak is at the top of the radiator it won't leak a lot so you won't see drips. But don't wait, replace it now before it really tears open on you as mine recently did!

 

When the head gaskets blew on mine, there was no subtle bubbling sound. The compression was being pushed out of the combustion chamber and into the coolant passages, forcing the coolant out of the engine and then the engine to QUICKLY overheat. The coolant was foamy, and was being pushed out the overflow bottle. Keep an eye out for these symptoms, or for milky looking oil if you suspect head gasket troubles.

 

Good luck!

Oi! Thanks for your replies.

 

It's a bit weird indeed the bubbling but I thought it was something with Subaru's - a lot of people over here (NZ) are driving Subaru Legacy's and so many of them made that funny bubbling that I actually started thinking that is was 'normal'...

 

The engine is a small EJ18 one with about 230.000KM on the odometer. I definitely don't want anything to happen with the head gasket. I have no idea how difficult it is to replace it in a Subaru but I replaced one in a VW LT28 in the Netherlands and that was not funny... but well, that's quite a different car

A leaky head gasket leads to quite a notable decrease in engine power doesn't it? I don't think it's the case with my Subaru...

 

Does the radiator not have a pressure relieve valve what might have caused the steam coming out? On the other hand, if it was such a valve, the steam would've come out in bursts and not a steady slow 'coffee steam rate', wouldn't it?

 

Thanks again!

NO, there is not a pressure relief valve. That is pretty much the function of the overflow bottle.

 

With a 1.8 you can do the HG's pretty easily with the engine in the car. If you aren't convinced that you have a HG problem, you could check your compression, or maybe a leak down test would be more telling.

Test your coolant for hydrocarbons. It's a cheap way to test if your HGs are going bad. If they are bad, join the club. Do it yourself and you'll never need a mechanic for anything ever again, lol.

"Characteristic Bubbling" does make you wonder about the HG's. That's not normal!

 

Sorry to ask, maybe a silly question, but why do you think it has something to do with the HG's? The last time I replaced the oil, I haven't spotted any coolant in it. The coolant itself is very clear as well, nice green color without any whitish/oily substance. The fluid around the radiator cap is rusty but as it is very local I guess this is due to the cap itself.

 

As for the coolant disappearing, your radiator shouldn't be steaming. If you see steam, then you have spotted your leak. If the leak is at the top of the radiator it won't leak a lot so you won't see drips. But don't wait, replace it now before it really tears open on you as mine recently did!

 

So is it more likely the radiator is leaking instead of the HG's? Sorry for all the difficult questions... it's my first car and recognizing symptoms is quite new to me.

Yes, if you see steam, that indicates a leak from the radiator that should not be there. I recommend replacement before it gets out of hand and overheats.

 

That does not exclude the HG's though (Both radiator and HG's COULD be a problem). The HG's can leak from the combustion chamber into a coolant passage. I'm not telling you that they are bad - if you have no symptoms, than maybe not. Testing for hydrocarbons in the coolant is an excellent idea, though I have no idea how to do that.

Also you can have a radiator shop test your radiator. They will pressurize it and make sure it holds pressure. I don't think it costs much to have it tested.

Yesterday I went to town with the Subaru and it appeared that the radiator was leaking at two places as well as the cap... got the rad replaced with a new one and got the coolant system flushed with some anti-rust thingy because of the large amount of rust in the coolant. Did a pressure test afterwards and there doesn't seem to be any leaks left in the cooling system. Haven't done a hydrocarbon test though so not sure about my HG's yet...