Dave_Parmenter

Hi,

I have a 1994 Legacy GT-B and when I accelerate I get a gurgling sound coming from behind the dashboard. and until now I have put this down to an air lock that won't budge in the heater matrix.

A few weeks ago I took it to a garage to get a new knock sensor fitted and the mechanic told me the gurgling sound was due to there being either porosity in a cylinder head or cylinder block and that exhaust gases were escaping the cylinder and getting in to the coolant causing this noise.

Naturally I'm a bit concerened about this so I thought I'd ask for other people's advice.

I thought that if this were happening water or steam from the coolant circuit would pass the other way in to the cylinder(s) so therefore I would see white smoke coming from the exhaust, but I followed my car for 30 miles with someone else driving it and there was no white smoke whatsoever during driving, apart from a small amount when starting the car from cold.

I will be taking the car to another mechanic on Monday as he's got a gas tester to put on the expansion tank cap to see if any exhaust gasses are getting in to the coolant.

I would like to know if anyone else has had this happen, or whether the garage was trying to get more money out of me! I have looked on this and other forums for porosity in Subaru engines and I haven't found a thing.

I bought the car from someone I know and he's done 30,000 miles in it with no problems and he said he had the same gurgling noise coming from the heater matrix, but hadn't been loosing any coolant, so I'm just hoping it's a stubborn air lock and not a porous block or dodgy head gasket!!


Any information on the subject would be appreciated.

Cheers,

Dave.

Fangoria

iTrader: (1)

It can take a while to fully find out (well easy to diagnose but an engine strip would be needed)

There should be an expansion breather for the Coolant - if after an energetic drive the Coolant is bubbling away in the Breather then either:

1. Your cylinder heads are cracked (most likely)
2. Your head gasket is going!!

Its a very easy test - even the AA can do it - FOC (if you have cover - just tell them the cars lost power and you think the head gasket has gone)

I noticed the coolant issues but then my Turbo stopped fully working

If gases are getting into the Collant then you'll have an expensive repair bill of probably several £k - which on a 1994 is clearly an issue

Does the car feel like its down on power at all - or cant you tell?

Best to check as it only takes about 5-10 minutes (less if its bad) and costs next to nothing to do (i.e. labour charges)

Dave_Parmenter

Thanks for the info,

I haven't noticed any loss in power whilst driving the car.

What do you mean by the expansion breather? Do you mean the expansion tank?

Cheers,

Dave.

Fangoria

iTrader: (1)

There should a pipe to let surplus Coolant out..... Mine was boling out of this - dont know where it is on your car but it should be easy to spot

Hopefully for you the gas analyser test will show no gases in the coolant mixture

If it changes to Green from Blue then you have problems!

APIDavid

iTrader: (4)

[QUOTE=Dave_Parmenter]Hi,

I have a 1994 Legacy GT-B and when I accelerate I get a gurgling sound coming from behind the dashboard. and until now I have put this down to an air lock that won't budge in the heater matrix.

A few weeks ago I took it to a garage to get a new knock sensor fitted and the mechanic told me the gurgling sound was due to there being either porosity in a cylinder head or cylinder block and that exhaust gases were escaping the cylinder and getting in to the coolant causing this noise.
Naturally I'm a bit concerened about this so I thought I'd ask for other people's advice.

I thought that if this were happening water or steam from the coolant circuit would pass the other way in to the cylinder(s) so therefore I would see white smoke coming from the exhaust, but I followed my car for 30 miles witsomeone else driving it and there was no white smoke whatsoever during driving, apart from a small amount when starting the car from cold.

I will be taking the car to another mechanic on Monday as he's got a gas tester to put on the expansion tank cap to see if any exhaust gasses are getting in to the coolant.

I would like to know if anyone else has had this happen, or whether the garage was trying to get more money out of me! I have looked on this and other forums for porosity in Subaru engines and I haven't found a thing.

I bought the car from someone I know and he's done 30,000 miles in it with no problems and he said he had the same gurgling noise coming from the heater matrix, but hadn't been loosing any coolant, so I'm just hoping it's a stubborn air lock and not a porous block or dodgy head gasket!!

Any information on the subject would be appreciated. Cheers,

2.5's do this quite often and once overheating sets in after a period of gurgling the engine is a throwaway. Never heard of a 2 litre doing it. It is a 'known' problem on 2.5's and many dealers will tell you that they:

First replaced the head gaskets - still gurgles, still overheats.

Second replaced the heads - still gurgles, still overheats, maybe not for 100 - 1500 miles after but it comes back.

Third change the engine - now fixed - With a rad change somewhere in the middle of the sequence to be sure.

We've tried to fix them after they've started overheating and we've been caught out under warranty both times. Now we build fresh 2.5 engines every time and any core - from a 2.5 Legacy - that comes back to us after overheating is thrown away. Pressure testing of the block halves and the heads seems to suggest nothing wrong - but they still keep on doing it.

On a 2 litre, I would suggest that whilst the gurgling is perhaps annoying, if it isn't using water or filling and pressurising the expansion tank - leave well alone. If it blows the gaskets then I would repair it rather than adopt the 2.5 'cure' of starting all over again.

We have a 2.5 out there somewhere that started gurgling again on a 'new' engine but doesn't seem to have deteriorated as the guy would have been back under warranty. It's been out there 2 years now.

David APi Engines / APi Impreza
www.apiengines.com

Dave_Parmenter

Hi,

Today I ran the engine up and did the test you suggested, but unfortunately my Legacy was blocked in on the drive so I couldn't take it out for a spin to get it nice and warm, so I just started it up and left it running for 30-40 minutes. I switched on the aircon, etc to put the engine under some load (well, as much as you can when it's stationary!) I revved the engine after it had warmed up and watched to see if any bubbling occurred in the expansion tank.

There was a pipe coming from the top of a small metal container on the top of the engine where the coolant filler cap is (towards the left as you are facing the car) that went into the top of a clear plastic tank with a yellow cap at the front of the engine bay by the radiator (which I am assuming is the expansion tank) and I watched the end of this pipe to see what was happening. After 45 minutes of running I couldn't see any bubbles coming from the end of this pipe and I couldn't smell any exhaust gasses coming from the container itself. I also left the engine running with the yellow cap on the tank and when I opened this there didn't seem to be any back pressure upon opening.

I don't know if this static test was sufficient, but I had no choice.

The car will be going to a mechanic on Monday for the proper test, so I'll just have to wait and see what the outcome of that will be.


Many thanks for everyone's advice!!!

Cheers,

Dave.

Dave_Parmenter

I got the coolant test done and it came up clear, PHEW!

Cheers to everyone for their advice,

Dave.