Astra J loosing coolant - no one knows issue

[RDC12399]

Astra J 2015 1.6 automatic petrol

Wondering if anyone has any ideas because I’m piss out of hope.

Around 6-7 days ago I noticed the heater wasn’t blowing out warm air - only cold. I checked my coolant level and it was basically empty which I thought was weird because it was filled up about 2 weeks prior. Filled it back up and about 20 minutes later whilst driving the heater finally worked. Woke up the morning after and the coolant was empty again and the heater not blowing warm air.

I have since taken it to 3 different mechanics, all reputable local mechanics with good reviews etc. They have all conducted pressure tests and they’ve all come back clear with no leaks. They have all checked the head gasket and this is fine. They have all bled the system and topped up the coolant only for it to be empty again the next day.

I really don’t know what to do at this stage. I don’t have a lot of money to throw away diagnosing the issue when everything seems to be ok. I’ve already spend around £400 trying to find the issue and I’ve been left with no answers - it feels like the mechanics don’t want to take on the job and just want to get rid of me..

My mechanic friend, who is currently only holiday so can’t check the car, has said even though all the mechanics say the head gasket is fine it’s still a huge possibility it’s blown.

Any ideas?

[donkmeister]

A lot of autos have the trans fluid cooled in the same radiator as the engine coolant. In some designs corrosion can lead to ATF and coolant mixing.

Can you see if there's a pair of small diameter pipes between the gearbox and the radiator?

It's probably not that as it would destroy your gearbox fairly quickly if that much coolant got in, but worth ruling in or out.

[trickywoo]

You can only have a leak.

Split expansion bottle is common but could be a hose or any of the connected ends.

If you can’t easily see the leak you could try uv dye and what the mericans like to call a black light.

[Scrump]

If you can’t see a leak then it had to go somewhere.
Have you checked the engine oil and the gearbox fluid to look for contamination?

[7 5 7]

Seems daft, but check coolant/header tank screw cap, sometimes these fail or the seal goes brittle, so vents it out when gets up to temp.

Cheap to replace or at least try, or is it screwed down correctly?

My Vauxhall waterpump was leaking, that was my issue.

Edited by 7 5 7 on Tuesday 9th January 21:00

[RDC12399]

Scrump said:

If you can’t see a leak then it had to go somewhere.
Have you checked the engine oil and the gearbox fluid to look for contamination?

No. I don’t know much about cars which is why I was paying a mechanic to sort the issue. I would assume they would have checked all of this already - I’d like to think so anyway

[RDC12399]

trickywoo said:

You can only have a leak.

Split expansion bottle is common but could be a hose or any of the connected ends.

If you can’t easily see the leak you could try uv dye and what the mericans like to call a black light.

Would a pressure test not have ruled a leak out? This is what I was told by all 3 garages

[RDC12399]

7 5 7 said:

Seems daft, but check coolant/header tank screw cap, sometimes these fail or the seal goes brittle, so vents it out when gets up to temp.

Cheap to replace or at least try, or is it screwed down correctly?

My Vauxhall waterpump was leaking, that was my issue.

Edited by 7 5 7 on Tuesday 9th January 21:00

You had the same issue and it was the water pump?

[7 5 7]

RDC12399 said:

You had the same issue and it was the water pump?

Yeah, different engine 1.8vvt Vauxhall - my waterpump was leaking, and had a very small weeping coolant pipe too, but only leaked when up to temperature so was hard to spot, but emptied the tank quite quickly, coolant light on etc

Has this been changed on yours? I suspect the mechanic has looked at this though, well you'd assume.

Or, it could be Thermostat if your heater isn't blowing hot too, just reread your original post

Edited by 7 5 7 on Tuesday 9th January 21:06

[RDC12399]

donkmeister said:

A lot of autos have the trans fluid cooled in the same radiator as the engine coolant. In some designs corrosion can lead to ATF and coolant mixing.

Can you see if there's a pair of small diameter pipes between the gearbox and the radiator?

It's probably not that as it would destroy your gearbox fairly quickly if that much coolant got in, but worth ruling in or out.

So quick update.

I filled the coolant to the fill line and took the car out for about 10 minutes. Let it get to temp, stays on 90 no problem and heater blowing hot air. Checked the level of the coolant when I got home and almost half of what I filled up had gone in the space of that 10 minute drive. Checked the engine bay/under the car and still no evidence of any leaks.

Wtf is going on..

[Pope]

In this cold weather I would be tempted to run it up to temp and leave it running; doors and bonnet open and see if you can see any steam coming from anywhere - it's going 'somewhere'.

Good shout from the previous answers on the auto transmission fluid cooler - if it's going into the transmission/cooler there is plenty of space in there before you'll see any visible signs (leaks etc). Get your guy to check the fluid 'just in case'?

You could also check the carpets under the dashboard - is it leaking from the heating system into the cabin? Can you smell coolant in the car?

Edited by Pope on Tuesday 9th January 23:19

[GreenV8S]

RDC12399 said:

Checked the engine bay/under the car and still no evidence of any leaks.

Wtf is going on..

You have a leak. Leaks don't always leave obvious evidence. Your only problem is to discover where the leak is.

[RDC12399]

GreenV8S said:

You have a leak. Leaks don't always leave obvious evidence. Your only problem is to discover where the leak is.

So what would be the next step? It’s has been pressure tested by 3 different mechanics and all came back clear. Does this test not look at everything?

At this point I’m thinking I may have to bring it to Vauxhall themselves

[fttm canada]

Heater matrix ?

[trickywoo]

How’s your sense of smell op?

Coolant stinks especially when it’s hot. Can you smell anything?

Does your radiator have chalky looking deposits on it?

[RDC12399]

trickywoo said:

How’s your sense of smell op?

Coolant stinks especially when it’s hot. Can you smell anything?

Does your radiator have chalky looking deposits on it?

Came out this morning to this under front of car

[E-bmw]

That looks more like dirty oil to me.

Having said that, as others have said it must be going somewhere if it is leaving the coolant system.

I have just now finally managed to diagnose an issue with my car (different engine) that may be a possibility.

It seems that my engine block has a crack in it.

Coolant full, everything going fine when driving for quite some time & then suddenly after an hour or so, the crack opens up, it fills the coolant system with combustion gases & ejects lots of water from the expansion tank.

I have done several "sniff tests" before without finding exhaust gases because as soon as you open the expansion tank to put the tester in, the gases escape.

Don't know if this has anything to do with your issue, but it took me a while to manage to rig up a different way of testing to enable me to finally confirm the gases in the coolant, most mechanics wouldn't go this far.

[5s Alive]

Pope said:

In this cold weather I would be tempted to run it up to temp and leave it running; doors and bonnet open and see if you can see any steam coming from anywhere - it's going 'somewhere'.

Edited by Pope on Tuesday 9th January 23:19

Best to do this in complete darkness with a torch. Not a phone but something with a defined beam. Even a small localised area of escaping steam will be very apparent.

Sounds very like a head gasket though, however unless it's ending up in the sump you should be able to spot steam out of the exhaust, even when hot, or water from the coolant overflow.

Might be easier to detect if you drive the car and stop every 2 minutes and check, assuming this is possible on the roads near you. It's fairly quiet at 2am, and dark!

Good luck, these issues are frustrating.

[trevalvole]

E-bmw said:

That looks more like dirty oil to me.

Coolant does stain driveways and given the timescales it'll probably still be wet which makes it more noticeable. Surely there is a good possibility that the OP has now found the leak?

[E-bmw]

trevalvole said:

E-bmw said:

That looks more like dirty oil to me.

Coolant does stain driveways and given the timescales it'll probably still be wet which makes it more noticeable. Surely there is a good possibility that the OP has now found the leak?

Obviously it is entirely possible, just passing on an opinion, hopefully, he will be able to give it a "sniff/feel test" and be able to tell the difference.