Water.... losing it ?

[RROB]

Ive had a right game over last few weeks....
Changed expansion tank and bottom hose....
new water pump and gasket fitted....

Still losing water after short runs with no visible signs in obvious areas (no damp carpets no white residue in oil).

Anyone ever had similar issues ?

usually losing around 1/2 to 1 litre each time I check ?

nothing obvious when car is running and up to temp ?

[bz4kev]

Was the system bleed correctly ie bmw procedure when expansion tank was done

[Grumpyowl]

I had similar last year and replaced similar plus radiator cap. Try a new cap
With all my messing about I replaced fluid 3 times make sure you raise the front on ramps when bleading.

[Mr Tidy]

Just wondering whether your car is a facelift? The facelifts with N52 engines have an electric water pump, which has an electric bleed procedure.

Hope you get it sorted.

[RROB]

Was the system bleed correctly ie bmw procedure when expansion tank was done

Have no idea what correct way is
I filled with car on raised drive
It was a swine to get bled is all I can say
Will persevere in my quest to find the golden leak !

[bz4kev]

Was the system bleed correctly ie bmw procedure when expansion tank was done

Have no idea what correct way is
I filled with car on raised drive
It was a swine to get bled is all I can say
Will persevere in my quest to find the golden leak !

Not a 100 percent sure but I have been told there is one good luck

[MKZ4000]

When, I had my coolant flushed and changed, i had to top up on about 3 occasions. It then levelled out.

Might have not bled properly

[Courageous]

What engine is it Rob? Was suffering similar and couldn't track it down for the last year. Finally "a leak" manifested itself in a bigger way with Steam issuing from under the bonnet. On the 2.0 there is a casting blanking plate on the rear of the block offside. Has two o rings as seals. One had perished and from time to time let go and pee streamed onto the exhaust. I'm hoping that's mine cured now. Took it to a well known indie in NW England whose name can't be mentioned for fear of waking the dead If that's your issue it's a ten minute job most would be capable of doing.

[RROB]

What engine is it Rob? Was suffering similar and couldn't track it down for the last year. Finally "a leak" manifested itself in a bigger way with Steam issuing from under the bonnet. On the 2.0 there is a casting blanking plate on the rear of the block offside. Has two o rings as seals. One had perished and from time to time let go and pee streamed onto the exhaust. I'm hoping that's mine cured now. Took it to a well known indie in NW England whose name can't be mentioned for fear of waking the dead If that's your issue it's a ten minute job most would be capable of doing.

its a 2.5 and proving to be a bloody mystery !!

[srhutch]

What engine is it Rob? Was suffering similar and couldn't track it down for the last year. Finally "a leak" manifested itself in a bigger way with Steam issuing from under the bonnet. On the 2.0 there is a casting blanking plate on the rear of the block offside. Has two o rings as seals. One had perished and from time to time let go and pee streamed onto the exhaust. I'm hoping that's mine cured now. Took it to a well known indie in NW England whose name can't be mentioned for fear of waking the dead If that's your issue it's a ten minute job most would be capable of doing.

its a 2.5 and proving to be a bloody mystery !!

M54 or N52?

Or pre facelift or post facelift?

[patriot66]

If it's a M54 2.5i then check the o-ring on the coolant temp sensor. No.5 in this diagram.

20190304_225722.jpg (84.22 KiB) Viewed 925 times

They can 'weep' slightly which runs down the underside of the radiator bottom hose and evaporates and/or blows away in the breeze which makes it difficult to trace. I speak from personal experience

[1000rr]

If it's a M54 2.5i then check the o-ring on the coolant temp sensor. No.5 in this diagram.
20190304_225722.jpg
They can 'weep' slightly which runs down the underside of the radiator bottom hose and evaporates and/or blows away in the breeze which makes it difficult to trace. I speak from personal experience

This. Had the same, took me an age to see where it was coming from.... no steam, and couldn’t find a leak. Until one morning a bit off coolant around the temp sensor after it wasn’t used a few days.

Sorted it for less than a tenner.

[tomrdy]

+1 on the temp sensor O ring, tho OP did mention he replaced the bottom coolant hose - could assume the sensor was replaced too?

I had a leak for months and months and didn't know what it was until I searched the forum for some ideas. Sensor was the cheapest and easiest to try first - turned out that was my source. Took a few minutes to do

[RROB]

Thanks chaps all for advise.... its the M54 engine
been out running it just it does seem to show a bit of water vapour from the xhaust when lifting the revs.... ok i know there will some when staring from cold.... but there does seem to be a bit too much for my liking at mo after 20mins of running up to temp ? head gasket ? from when original expansion tank went ?
its been pressure tested supposidly.... ?? mmmmm Dr Watson "what do you think" ??

[patriot66]

Thanks chaps all for advise.... its the M54 engine
been out running it just it does seem to show a bit of water vapour from the xhaust when lifting the revs.... ok i know there will some when staring from cold.... but there does seem to be a bit too much for my liking at mo after 20mins of running up to temp ? head gasket ? from when original expansion tank went ?
its been pressure tested supposidly.... ?? mmmmm Dr Watson "what do you think" ??

Does it take 20 mins to reach operating temperature ? If so something is definitely not right. You said originally that it is losing 1/2 to 1 litre of coolant every time you check. That sounds like an awful lot to lose across the head gasket without some going into the oil galleries. Have you checked your oil level ? Any mayo on the stick or under the filler cap ?