Need opinions on coolant disappearing.

[15Michaeljoseph]

So on the m20, if you're loosing antifreeze, and you have no leaks anywhere (pressure tested system several times, new hoses and rad.), it's not going out the overflow (catch bottle hooked up), and it's not going into the oil... where does it go?

I've been trying to figure this one out for about a year. help me please. my indie shop has no idea, and neither do I. It doesn't make any sense. as I said, it's been pressure tested, leakdown tested, tested for hydrocarbons... nothing.

I don't want to buy and install a new engine if I don't have too, but I'm going through a tank of coolant in about 11 days daily driving. It's gotta stop and I'm desperate.


--Mike

[mr.vang]

Check your heater core.

[Dirty325ix]

Is the carpet wet inside the care. especially around the drivers side feet area.
Does it drip a lot when the car is parked

[15Michaeljoseph]

Is the carpet wet inside the care. especially around the drivers side feet area.
Does it drip a lot when the car is parked

It doesn't drip at all. nothing. and the only residue in the bay is from the hoses I changed. Carpet isn't wet, but I'll be taking my console out to replace the ETS soon, so I'll check around the core to be sure.
I do have paperwork that indicates that that core recall was performed however, but it doesn't mean anything now i guess.

I should also not that the car doesn't overheat, and in fact runs a bit on the cool side.


--Mike

[uturn]

Check the hose on the side of the block above the starter under the manifold. It's a dark place where leaks like to hide. Also the heater core pipes, they tend to corrode where they attach to the hoses at the firewall.

[15Michaeljoseph]

it's funny you should say that. two weeks ago there were a few drips on the floor and I thought "yes finally this is going to be it", but it was just a heater hose....the one from the head into the heater. replaced hose, leak gone, car still drinking coolant like it's pay day.

seems like you guys think it's all the heater core... well I'll be paying it a visit soon.


--Mike

[15Michaeljoseph]

Need opinions on coolant disappearing.

I should also add that I recently rebuilt my throttle body, so there's no little leaks there. I know that's a common spot too.

[dnguyen1963]

Are you sure that your HG is okay? A small leak can eat up a lot of coolant.

[Liquidity]

Head gasket.

[mpowerful]

Have you replaced the res cap. Could be belching small amounts out here and there.

[15Michaeljoseph]

Head gasket.

I mean, i GUESS, but I've got no milkshake oil. is it possible for the coolant leaking from the headgasket to evaporate, say, IN the oil so I wouldn't know? The oil is a little lighter brown with tiny amounts of whitish snot on the filler cap and dipstick, but I always attributed that to short trips with the car. plus the oil level doesn't go up... if there was that much coolant in the oil, the level would rise right?
Also, I've had the cylinders leakdown tested at my local indie shop, guy says it's good. I trust this forum more than them though.

Have you replaced the res cap. Could be belching small amounts out here and there.

Bought a new cap, and I have a catch bottle hooked up to the overflow hose. nothing comes out.


So things to consider so far:

some sort of issue with the heater core (more unlikely), or an issue with the head (more likely).

Thanks so much guys I just wanted to get some opinions, picking your brains a bit to get all your different suggestions. maybe someone has some secret knowledge or experience haha


--Mike

[Liquidity]

Why would you think the only place the coolant could go is into the oil?

[sittingaaron]

Coolant is most likely being boiled out through the coolant cap. When the spring that pressurizes the system gets weak, it reduces the pressure, which reduces the boiling point, which will cause a disappearance in coolant. There could be a slight leak in the head gasket, but that's less likely and obviously more invasive, so try this first.

[15Michaeljoseph]

Why would you think the only place the coolant could go is into the oil?

Well I mean with the tests I've had done, It would appear as though there's no external leakage... so where else could it go really? If you pump the system with pressure and it holds overnight, it can't be leaking anywhere, right? unless the leak was internal, and then it may still hold pressure. I mean that's my idea of it all, anyway. The knowlege on this forum is waaay way way more than I'll ever know, so I'm not trying to come off sounding ignorant or anything. obviously I know that the coolant could go other places than the oil, it just kind of seems like it's completely disappearing.

Coolant is most likely being boiled out through the coolant cap. When the spring that pressurizes the system gets weak, it reduces the pressure, which reduces the boiling point, which will cause a disappearance in coolant. There could be a slight leak in the head gasket, but that's less likely and obviously more invasive, so try this first.

I completely understand. I'm completely at a loss for whatever the heck is going on. I've already relaced the old cap with a new one, and I have a catch bottle hooked up to the overflow hose, the bottle remains empty, exept for a drip or two (probably from when I fill the reservoir, some gets through the hose).
I just don't understand it, because this would be the only other logical explaination. If it's holding pressure in the system, then that points to the cap as the weak point, but it can't be, because my catch bottle would be getting filled up. that's what's so darn crazy about it all.






--Mike

[Andy.B]

Are you doing coolant leak tests with the engine hot? Some leaks open up more when the engine is hot, such as cracks in the block or head. When I worked at Land Rover, we had a particularly hard to diagnose leak due to a crack in the block, INTO A CYLINDER. It only leaked when the block was hot, and another tech finally found it when he ran the engine till it was hot, hooked up the pressure sensor, and stuck a scope into the cylinders to look for evidence of a leaky head gasket, only to see a fine spray halfway down the cylinder.