Originally Posted by sgking (Post 11986118)

Ok well i can drive her around the farm just fine (obviously limted driving mind)

But whenever i top the coolant reservoir up with water it always dissapears to low level?

I did a compression test today and here are the results:

passenger side front cylinder = 240 psi
passenger side rear cylinder = 238 psi
drivers side front cylinder = 238 psi
drivers side rear cylinder = 240 psi

What do you make of them figures then? Car was warmed up and each cylinder tested twice to make sure. Brand new draper tester no 37442.

Both drivers side spark plugs have oil on them (engine side, not the ceramic side)

pics to follow so you can see what the pugs look like.

Thanks

Originally Posted by ALi-B (Post 11986153)

Back to basics...measure how much coolant you are topping up by.
I add 500ml water each time to the overfill tank to fill it up but it just dissappears after an hourish and then the overfill tank happily sits at low until i top up again ? I dont understand where this water is going? What makes matters worse is the liquid coming out of the exhaust is greeny coolant colour! So my thinking is that the coolant is coming out the exhaust and my topping up with water is replacing it. But i cant explain the 'stable' compression test readings.... It would be good to test the water coming out the exhaust...but i'm not sure how.
The level in the expansion reservoir can vary, depending on ambient temp and pressure..that's why it has a H and L mark. As long as it doesn't overflow when hot or after a drive, there is no major issue in that respect.

If it drops below L, then top it up to mid way between H and L. Measure how much and make a note of it, and for how long it lasts before it needs topping up. As above. 500ml water lasts an hourish of idle before the overflow res ends up at low mark.It doesn't hold much so if you are only topping up by a little and getting a lot more water out the tailpipe than what you are putting in, then I may suspect you are worrying over nothing. you are right in that i think more is coming out of the tailpipe than i am putting in. I filled a jug the first time i noticed this. Needing to top-up by small amounts "may" indicate a gasket issue in its early stages, but more often than not its a leak where coolant escapes as steam - so there is no coolant drips. Tell tale clue is crystallised antifreeze in the area of leakage...assuming it has enough antifreeze in there. I need to get under the car for a look really. To see if i can see any leaks. Are there any known weak points for me to look?

Steam and water out of exhaust at this time of year is more often than not from combustion of fuel (hydrocarbons plus oxygen = water ). Subaru Turbo engines run very low compression compared with many other cars, as such combustion at idle is pretty inefficient, as such exhaust and cat (assuming it still has cars) (Yes still has all cats in place) temperatures are lower and more steam condenses, causing great white clouds (I used to get engulfed in steam with my scoob when backing it out the garage on cold day...my jag is even worse to the point I can't see anything when reversing off the drive LOL).

If you have a decat and dustbin exhaust (i have standard cat and standard exhaust) (tail pipe larger than 3" ), exhaust temp and gas velocity will be low and slow enough to cause steam to condense and build up in the back box in a big way. Especially as most aftermarket "tuner" styled back boxes are of a bad design where the pipe is angled as such that condensed steam runs down and collects at a low point by the rear diff. I suspect this maybe the main cause of your water-in-exhaust issues (and why most tuner style back boxes rot from the inside out).

Still doesn't mean the head gasket is not prone; If the coolant has been neglected where old antifreeze has gone corrosive then the gasket will be weakened. (the coolant has not been changed for a long time so this could very well be happening, and i would accept it, except the compression test figures suggest the HG is ok? - i have read around on forrester and legacy websites and high compression figures are not all that uncommon on the NA cars?) This is why these cars have 3yr change intervals (5yr on later models if used with genuine antifreeze). The usual symptom is cooling system over-pressurisation after bringing onto high boost; where coolant overflows out the expansion reservoir (pipe the overflow to a empty drink bottle), and the presence of hydrocarbons in the header tank.

Air locks are common as mentioned. Also worth pointing air locks can cause a head gasket to fail. And also a head gasket fail can cause an air lock (as it leaks combustion gas into the cooling system): A viscious circle.I dont think i have an air lock as it warms up ok and pipes all feel hot. Are there any tests i can perform?

Invariably as the HG require engine removal and strip down, I would only condem it if

a) the cooling system over pressurises after being drained and refilled and eradicated of air (I personally use a Bluepoint vacuum filler...works a treat on airlock prone engines like on Scoobs and Rover K series etc ). Nice bit of kit, i'd love one but its not on the shopping list unfortunatley! If i feel that this car will be used again then i will refill with fresh coolant for mot, using the guide on here.

b) engine overheats, despite confirming correct thermostat operation, adequate coolant flow and no radiator/heater blockages (inlet/outlet and engine temps confirmed with laser thermometer). No overheating experienced and flow seems fine so far?

c) Hydrocarbons present in header tank (note header tank, not expansion reservoir). - On NA impreza there is only a rad and an overflow bottle next to it? you will need to syphon off about 60% of coolant out of the tank in order not to make a mess everywhere and give space for gases to accumulate before "sniffing" with a gas analyser upon cap removal.

Originally Posted by Wull (Post 11986216)

The good thing is all 4 are pretty close, but they do seem high. I was of the understanding that 160 was the rough number to hope for. Not sure whether it makes much odds if done from cold or hot but the key is for them all to be within a certain % of each other.

Originally Posted by sgking (Post 11986550)

i thankd for your replies. I have responses below in RED. Much thanks to you for taking the time to write me such a full reply Ali, it is appreciated.

I think a sniff test is next on the list TBH but car is sorned. Are these sniff tests portable i.e can i get a mechanic to bring one over? Can i even buy one i wonder?

Again, thank you for your help on this. In case it helps, car is a 2002 bugeye sport NA with 160k. Its my GF's car and shes almost had enough of it now, sadly. We have owned it for 11 years and I recently fitted a new clutch and s/h gearbox recently so i have a soft spot for it!