Burning coolant?

[Rsnail]

Got a new problem with the cooling system I guess. It's been developing over the last months, and that is, it looses about 1l of coolant every 2 weeks approximately, checked everything, thermostat and pipes not leaking, engine V is bone dry, radiator not leaking, checked even the heater matrix and that one's not leaking either, also done a chemical test which checks for exhaust gases in the coolant and that's also good, so it seems to me that there's no external leakage, also, not even a drop of coolant found on the ground as I always park the car in the same spot... But now thing is, is it really possible for the engine to burn that much coolant in such a short time? The only logical place where it could leak would be the intake manifold gasket/s I think, but that seems odd as I replaced those too when replacing the thermostat about almost a year ago and never had a problem until lately... Also, after starting the car and leaving it to idle for 10 minutes, when I look under the exhaust it creates kind of a wet patch on the asphalt, like 10x10cm large and when holding my hand right against the exhaust pipes' endings, after about half a minute my palm gets wet too, also, theres some whitish smoke blowing out which is seen also when accelerating. Now all of this makes one believe that it's burning coolant, but what should be done to know 100% if it's the case? If there wouldn't be a problem in the long run, I wouldn't hassle with it anymore.

Also to notice is that the oil is perfectly clean and not even a sign of coolant mixed with oil on the oil cap or dipstick.

[macafee2]

not uncommon for steam and water to come out of the exhaust when a car is first started and even for a few minutes afterwards, it is condensation from within the exhaust pipe.

macafee2

[vitesse]

Have a look at the outer spark plugs, if your machine is leaking coolant via the IMG(s) there will probably be a difference in the colour of the spark plugs.

Member Lovel states that after replacing the IMGs he always goes back sometime later and checks the tightness of the bolts.

Regards

[Rsnail]

What do you mean by IMG's? And by checking them you mean taking them out and seeing how the electrodes look like or checking something from the outside? Anyway, I replaced the spark plugs about 2 months ago because of misfires. And even if the engine is loosing coolant via the spark plugs, replacing the plugs wouldn't change anything because that is not the cause of the leak, that's just an effect because obviously no coolant should find it's way in the combustion chamber

[T-Cut]

Originally Posted by Rsnail

Also, after starting the car and leaving it to idle for 10 minutes, when I look under the exhaust it creates kind of a wet patch on the asphalt, like 10x10cm large and when holding my hand right against the exhaust pipes' endings, after about half a minute my palm gets wet too

Whenever something burns it creates carbon dioxide and water - and lots of it. In fact when a gallon of petrol is burned in an engine, approximately a gallon of water is produced. Of course, this comes out of the exhaust as a gas (steam). When everything is cold, some of the steam condenses in the exhaust system to be expelled as water droplets. In very cold weather it may even pour out of the tailpipe as a steady stream. So, water from the exhaust pipe is normal. The water 'disappears' when everything gets hot enough to prevent it condensing.

also, theres some whitish smoke blowing out which is seen also when accelerating. Now all of this makes one believe that it's burning coolant

Smoke and steam/vapour are different things. If an engine burms some oil, there will be a bluish coloured smoke, which will persist for several seconds until it's gradually dispersed by the wind. White water vapour from the exhaust usually evaporates very quickly under normal conditions. So, if you see lots of white vapour when other vehicles are not doing it, then you have a problem. 'Combusting' coolant (which is 50% ethylene glycol) will generate a mixture of water vapour and ethylene glycol vapour, which has a denser white appearance.


From what you describe (including the misfiring) I'd say the coolant is leaking through the inlet manifold seals and into the cylinders where it's being 'combusted'.


TC

[Rsnail]

Thank you so much TC. Well in my case even after 15 mins of letting the car idle and getting the engine to normal operating temperature, the white smoke is still visible enough when idling, but especially when revving up the engine.

And one more thing though, the misfiring was solved about 2 months ago, the cause was one of the spark plugs, at 250000km on board it still had the original ones fitted.

But as said, the white smoke is still noticeably present even well after the engine is hot, and water particles are still being released from the exhaust, I say this because I moved the car after 15 minutes of letting it heat up, and after another 15 minutes it left behind the same wet patch on the asphalt as it did in the first 15 minutes, and also, when putting my hand on the exhaust holes after the first 15 minutes, my hand still got wet after holding it there for about 30 seconds.

So now the question I have: is it possible to test the inlet gasket without taking everything apart and visually inspecting it?

[T-Cut]

You can't 'test' the seals as such, but maybe you could detect water/coolant in one or more cylinders? If so, then it's most likely the manifold seals are leaking.

Coolant getting into a cylinder often causes the spark plug to exhibit a bleached/washed appearance. The ceramic part may actually be tinted the colour of the antifreeze you use. At the reported rate the coolant is leaking from the cooling system, there might ge a good chance of seeing droplets or a small puddle on one or more pistons. Maybe time to buy/borrow a borescope (a borrowscope perhaps?)

TC

[Rsnail]

That's a good idea! I actually happen to have a small led endoscope inspection camera which will surely fit into the spark plug hole, but can you really see the droplets on the cylinder? Wouldn't they be pushed out through the valves just like the exhaust gases?

[trikey]

Start the car from cold, run for a minute, leave to cool down overnight then remove the spark plugs, I bet one of them will have signs of rust where the water is getting into the cylinder.

[T-Cut]

The coolant may well be leaking all the time, so let it stand a few day. Keep coolant well topped up to the brim to add some pressure. Maybe also raise the header tank as far as it will go. Don't start the engine. Remove spark pluhs and with a bit of 'luck' you'll see it. Worth a shot anyway.


TC